Input Device Characteristics Contribute to Performance during Training to Operate a Simulated Micro-Unmanned Aerial Vehicle

DTIC Science & Technology

2010-10-01

mission, participants were given the NASA Task Load Index ( NASA TLX ) to measure subjective workload. Additional performance measures included mission...16 NASA TLX Workload Analyses...worksheet (See Appendix C), the Hidden Patterns Test (ETS, 1976), and an electronic form of the NASA Task Load Index ( TLX ; Hart & Staveland, 1988). The

Stability and Workload of the Virtual Reality-Based Simulator-2.

PubMed

Kamaraj, Deepan C; Dicianno, Brad E; Mahajan, Harshal P; Buhari, Alhaji M; Cooper, Rory A

2016-07-01

To assess the stability of clinicians' and users' rating of electric-powered wheelchair (EPW) driving while using 4 different human-machine interfaces (HMIs) within the Virtual Reality-based SIMulator-version 2 (VRSIM-2) and in the real world (accounting for a total of 5 unique driving conditions). Within-subjects repeated-measures design. Simulation-based assessment in a research laboratory. A convenience sample of EPW athletes (N=21) recruited at the 31st National Veterans Wheelchair Games. Not applicable. Composite PMRT scores from the Power Mobility Road Test (PMRT); Raw Task Load Index; and the 6 subscale scores from the Task Load Index developed by the National Aeronautics and Space Administration (NASA-TLX). There was moderate stability (intraclass correlation coefficient between .50 and .75) in the total composite PMRT scores (P<.001) and the users' self-reported performance scores (P<.001) among the 5 driving conditions. There was a significant difference in the workload among the 5 different driving conditions as reflected by the Raw Task Load Index (P=.009). Subanalyses revealed this difference was due to the difference in the mental demand (P=.007) and frustration (P=.007) subscales. Post hoc analyses revealed that these differences in the NASA-TLX subscale scores were due to the differences between real-world and virtual driving scores, particularly attributable to the conditions (1 and 3) that lacked the rollers as a part of the simulation. Further design improvements in the simulator to increase immersion experienced by the EPW user, along with a standardized training program for clinicians to deliver PMRT in VRSIM-2, could improve the stability between the different HMIs and real-world driving. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Physiological Self-Regulation and Adaptive Automation

NASA Technical Reports Server (NTRS)

Prinzell, Lawrence J.; Pope, Alan T.; Freeman, Frederick G.

2007-01-01

Adaptive automation has been proposed as a solution to current problems of human-automation interaction. Past research has shown the potential of this advanced form of automation to enhance pilot engagement and lower cognitive workload. However, there have been concerns voiced regarding issues, such as automation surprises, associated with the use of adaptive automation. This study examined the use of psychophysiological self-regulation training with adaptive automation that may help pilots deal with these problems through the enhancement of cognitive resource management skills. Eighteen participants were assigned to 3 groups (self-regulation training, false feedback, and control) and performed resource management, monitoring, and tracking tasks from the Multiple Attribute Task Battery. The tracking task was cycled between 3 levels of task difficulty (automatic, adaptive aiding, manual) on the basis of the electroencephalogram-derived engagement index. The other two tasks remained in automatic mode that had a single automation failure. Those participants who had received self-regulation training performed significantly better and reported lower National Aeronautics and Space Administration Task Load Index scores than participants in the false feedback and control groups. The theoretical and practical implications of these results for adaptive automation are discussed.

Effect of Task Load Interventions on Fatigue in Emergency Medical Services Personnel and Other Shift Workers: A Systematic Review

DOT National Transportation Integrated Search

2018-01-11

Modifying the task load of Emergency Medical Services (EMS) personnel may mitigate fatigue, sleep quality and fatigue related risks. A review of the literature addressing task load interventions may benefit EMS administrators as they craft policies r...

Gaze entropy reflects surgical task load.

PubMed

Di Stasi, Leandro L; Diaz-Piedra, Carolina; Rieiro, Héctor; Sánchez Carrión, José M; Martin Berrido, Mercedes; Olivares, Gonzalo; Catena, Andrés

2016-11-01

Task (over-)load imposed on surgeons is a main contributing factor to surgical errors. Recent research has shown that gaze metrics represent a valid and objective index to asses operator task load in non-surgical scenarios. Thus, gaze metrics have the potential to improve workplace safety by providing accurate measurements of task load variations. However, the direct relationship between gaze metrics and surgical task load has not been investigated yet. We studied the effects of surgical task complexity on the gaze metrics of surgical trainees. We recorded the eye movements of 18 surgical residents, using a mobile eye tracker system, during the performance of three high-fidelity virtual simulations of laparoscopic exercises of increasing complexity level: Clip Applying exercise, Cutting Big exercise, and Translocation of Objects exercise. We also measured performance accuracy and subjective rating of complexity. Gaze entropy and velocity linearly increased with increased task complexity: Visual exploration pattern became less stereotyped (i.e., more random) and faster during the more complex exercises. Residents performed better the Clip Applying exercise and the Cutting Big exercise than the Translocation of Objects exercise and their perceived task complexity differed accordingly. Our data show that gaze metrics are a valid and reliable surgical task load index. These findings have potential impacts to improve patient safety by providing accurate measurements of surgeon task (over-)load and might provide future indices to assess residents' learning curves, independently of expensive virtual simulators or time-consuming expert evaluation.

Comparison of postural ergonomics between laparoscopic and robotic sacrocolpopexy: a pilot study.

PubMed

Tarr, Megan E; Brancato, Sam J; Cunkelman, Jacqueline A; Polcari, Anthony; Nutter, Benjamin; Kenton, Kimberly

2015-02-01

To compare resident, fellow, and attending urologic and gynecologic surgeons' musculoskeletal and mental strain during laparoscopic and robotic sacrocolpopexy. Prospective cohort study (Canadian Task Force classification II-2). Academic medical center. Patients who underwent robotic or laparoscopic sacrocolpopexy from October 2009 to January 2011. The Body Part Discomfort (BPD) survey was completed before cases, and the National Aeronautics and Space Administration Task Load Index and BPD survey were completed after cases. Higher scores on BPD and the National Aeronautics and Space Administration Task Load Index indicate greater musculoskeletal discomfort and mental strain. BPD scores were averaged over the following body regions: head/neck, back, hand/wrist, arms, and knees/ankles/feet. Changes in body region-specific discomfort scores were the primary outcomes. Multivariable analysis was performed using mixed-effects linear regression with surgeon as a random effect. Sixteen surgeons participated (53% fellows, 34% residents, and 13% attendings). Thirty-three robotic and 53 laparoscopic cases were analyzed, with a median surgical time of 231 minutes (interquartile range, 204-293 minutes) versus 227 minutes (interquartile range, 203-272 minutes; p = .31), a median estimated blood loss of 100 mL (interquartile range, 50-175 mL) versus 150 mL (interquartile range, 50-200 mL; p = .22), and a mean patient body mass index of 27 ± 4 versus 26 ± 4 kg/m(2) (p = .26), respectively. Robotic surgeries were associated with lower neck/shoulder (-0.19 [interquartile range, -0.32 to -0.01], T = -2.49) and back discomfort scores (-0.35 [interquartile range, -0.58 to 0], T = -2.38) than laparoscopic surgeries. Knee/ankle/foot and arm discomfort increased with case length (0.18 [interquartile range, 0.02-0.3], T = 2.81) and (0.07 [interquartile range, 0.01-0.14], p = .03), respectively. Surgeons performing minimally invasive sacrocolpopexy experienced less neck, shoulder, and back discomfort when surgery was performed robotically. Copyright © 2015 AAGL. Published by Elsevier Inc. All rights reserved.

Assessment of workload using NASA Task Load Index in perianesthesia nursing.

PubMed

Young, Gloria; Zavelina, Lyubov; Hooper, Vallire

2008-04-01

According to the Institute of Medicine (IOM), as many as 44,000 to 98,000 people in the United States die in hospitals every year due to medical errors. Multiple physiological and psychological factors can impact the health care provider's attention span, making medical errors more likely. Some of these factors include increased workload, fatigue, cognitive overload, ineffective interpersonal communications, and faulty information processing. Postanesthesia nurses, responsible for providing care to unstable patients emerging from anesthesia with multiple life-threatening conditions, must make critical decisions on a minute-by-minute basis. The current ASPAN Patient Classification/Recommended Staffing Guidelines does not adequately take into account varying care requirements among the patients. If a tool could be found that effectively evaluated staff's workload, ongoing assessment would be enhanced and resources better used. The National Aeronautics and Space Administration-Task Load Index (NASA-TLX), a multifaceted tool for evaluating perceptual (subjective) workload, has seen extensive applications and is widely regarded as the strongest tool available for reporting perceptions of workload. This article will survey various uses of the NASA-TLX and consider the potential uses for this tool in perianesthesia nursing.

Cognitive Aspects and Behavioral Effects of Transitions Between Levels of Automation

DTIC Science & Technology

2007-01-06

operator’s mental load: − changes in performance due to the allocation of resources to multiple tasks; − operator’s self-reports (e.g., NASA - TLX , SWAT...difficulty was randomized across participants. After each block participants compiled the NASA -Task Load indeX ( NASA - TLX : Hart & Staveland, 1988) for...the subjective assessment of mental workload. DATA ANALYSIS AND RESULTS NASA - TLX weighted scores and number of completed lines (an index of

Maximizing Efficiency and Reducing Robotic Surgery Costs Using the NASA Task Load Index.

PubMed

Walters, Carrie; Webb, Paula J

2017-10-01

Perioperative leaders at our facility were struggling to meet efficiency targets for robotic surgery procedures while also maintaining the satisfaction of the surgical team. We developed a human resources time and motion study tool and used it in conjunction with the NASA Task Load Index to observe and analyze the required workload of personnel assigned to 25 robotic surgery procedures. The time and motion study identified opportunities to enlist the help of nonlicensed support personnel to ensure safe patient care and improve OR efficiency. Using the NASA Task Load Index demonstrated that high temporal, effort, and physical demands existed for personnel assisting with and performing robotic surgery. We believe that this process could be used to develop cost-effective staffing models, resulting in safe and efficient care for all surgical patients. Copyright © 2017 AORN, Inc. Published by Elsevier Inc. All rights reserved.

A self-analysis of the NASA-TLX workload measure.

PubMed

Noyes, Jan M; Bruneau, Daniel P J

2007-04-01

Computer use and, more specifically, the administration of tests and materials online continue to proliferate. A number of subjective, self-report workload measures exist, but the National Aeronautics and Space Administration-Task Load Index (NASA-TLX) is probably the most well known and used. The aim of this paper is to consider the workload costs associated with the computer-based and paper versions of the NASA-TLX measure. It was found that there is a significant difference between the workload scores for the two media, with the computer version of the NASA-TLX incurring more workload. This has implications for the practical use of the NASA-TLX as well as for other computer-based workload measures.

Hands-free administration of subjective workload scales: acceptability in a surgical training environment.

PubMed

Carswell, C Melody; Lio, Cindy H; Grant, Russell; Klein, Martina I; Clarke, Duncan; Seales, W Brent; Strup, Stephen

2010-12-01

Subjective workload measures are usually administered in a visual-manual format, either electronically or by paper and pencil. However, vocal responses to spoken queries may sometimes be preferable, for example when experimental manipulations require continuous manual responding or when participants have certain sensory/motor impairments. In the present study, we evaluated the acceptability of the hands-free administration of two subjective workload questionnaires - the NASA Task Load Index (NASA-TLX) and the Multiple Resources Questionnaire (MRQ) - in a surgical training environment where manual responding is often constrained. Sixty-four undergraduates performed fifteen 90-s trials of laparoscopic training tasks (five replications of 3 tasks - cannulation, ring transfer, and rope manipulation). Half of the participants provided workload ratings using a traditional paper-and-pencil version of the NASA-TLX and MRQ; the remainder used a vocal (hands-free) version of the questionnaires. A follow-up experiment extended the evaluation of the hands-free version to actual medical students in a Minimally Invasive Surgery (MIS) training facility. The NASA-TLX was scored in 2 ways - (1) the traditional procedure using participant-specific weights to combine its 6 subscales, and (2) a simplified procedure - the NASA Raw Task Load Index (NASA-RTLX) - using the unweighted mean of the subscale scores. Comparison of the scores obtained from the hands-free and written administration conditions yielded coefficients of equivalence of r=0.85 (NASA-TLX) and r=0.81 (NASA-RTLX). Equivalence estimates for the individual subscales ranged from r=0.78 ("mental demand") to r=0.31 ("effort"). Both administration formats and scoring methods were equally sensitive to task and repetition effects. For the MRQ, the coefficient of equivalence for the hands-free and written versions was r=0.96 when tested on undergraduates. However, the sensitivity of the hands-free MRQ to task demands (η(partial)(2)=0.138) was substantially less than that for the written version (η(partial)(2)=0.252). This potential shortcoming of the hands-free MRQ did not seem to generalize to medical students who showed robust task effects when using the hands-free MRQ (η(partial)(2)=0.396). A detailed analysis of the MRQ subscales also revealed differences that may be attributable to a "spillover" effect in which participants' judgments about the demands of completing the questionnaires contaminated their judgments about the primary surgical training tasks. Vocal versions of the NASA-TLX are acceptable alternatives to standard written formats when researchers wish to obtain global workload estimates. However, care should be used when interpreting the individual subscales if the object is to make comparisons between studies or conditions that use different administration modalities. For the MRQ, the vocal version was less sensitive to experimental manipulations than its written counterpart; however, when medical students rather than undergraduates used the vocal version, the instrument's sensitivity increased well beyond that obtained with any other combination of administration modality and instrument in this study. Thus, the vocal version of the MRQ may be an acceptable workload assessment technique for selected populations, and it may even be a suitable substitute for the NASA-TLX. Copyright © 2010 Elsevier Ltd. All rights reserved.

Relating physician's workload with errors during radiation therapy planning.

PubMed

Mazur, Lukasz M; Mosaly, Prithima R; Hoyle, Lesley M; Jones, Ellen L; Chera, Bhishamjit S; Marks, Lawrence B

2014-01-01

To relate subjective workload (WL) levels to errors for routine clinical tasks. Nine physicians (4 faculty and 5 residents) each performed 3 radiation therapy planning cases. The WL levels were subjectively assessed using National Aeronautics and Space Administration Task Load Index (NASA-TLX). Individual performance was assessed objectively based on the severity grade of errors. The relationship between the WL and performance was assessed via ordinal logistic regression. There was an increased rate of severity grade of errors with increasing WL (P value = .02). As the majority of the higher NASA-TLX scores, and the majority of the performance errors were in the residents, our findings are likely most pertinent to radiation oncology centers with training programs. WL levels may be an important factor contributing to errors during radiation therapy planning tasks. Published by Elsevier Inc.

EEG-based cognitive load of processing events in 3D virtual worlds is lower than processing events in 2D displays.

PubMed

Dan, Alex; Reiner, Miriam

2017-12-01

Interacting with 2D displays, such as computer screens, smartphones, and TV, is currently a part of our daily routine; however, our visual system is built for processing 3D worlds. We examined the cognitive load associated with a simple and a complex task of learning paper-folding (origami) by observing 2D or stereoscopic 3D displays. While connected to an electroencephalogram (EEG) system, participants watched a 2D video of an instructor demonstrating the paper-folding tasks, followed by a stereoscopic 3D projection of the same instructor (a digital avatar) illustrating identical tasks. We recorded the power of alpha and theta oscillations and calculated the cognitive load index (CLI) as the ratio of the average power of frontal theta (Fz.) and parietal alpha (Pz). The results showed a significantly higher cognitive load index associated with processing the 2D projection as compared to the 3D projection; additionally, changes in the average theta Fz power were larger for the 2D conditions as compared to the 3D conditions, while alpha average Pz power values were similar for 2D and 3D conditions for the less complex task and higher in the 3D state for the more complex task. The cognitive load index was lower for the easier task and higher for the more complex task in 2D and 3D. In addition, participants with lower spatial abilities benefited more from the 3D compared to the 2D display. These findings have implications for understanding cognitive processing associated with 2D and 3D worlds and for employing stereoscopic 3D technology over 2D displays in designing emerging virtual and augmented reality applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Mobility Case Studies : Where Integrated Corridor Management Has Worked and Why

DOT National Transportation Integrated Search

2018-01-11

Background: Modifying the task load of Emergency Medical Services (EMS) personnel may mitigate fatigue, sleep quality and fatigue related risks. A review of the literature addressing task load interventions may benefit EMS administrators as they craf...

Subjective and psychophysiological indexes of listening effort in a competing-talker task.

PubMed

Mackersie, Carol L; Cones, Heather

2011-02-01

The effects of noise and other competing backgrounds on speech recognition performance are well documented. There is less information, however, on listening effort and stress experienced by listeners during a speech-recognition task that requires inhibition of competing sounds. The purpose was (a) to determine if psychophysiological indexes of listening effort were more sensitive than performance measures (percentage correct) obtained near ceiling level during a competing speech task, (b) to determine the relative sensitivity of four psychophysiological measures to changes in task demand, and (c) to determine the relationships between changes in psychophysiological measures and changes in subjective ratings of stress and workload. A repeated-measures experimental design was used to examine changes in performance, psychophysiological measures, and subjective ratings in response to increasing task demand. Fifteen adults with normal hearing participated in the study. The mean age of the participants was 27 (range: 24-54). Psychophysiological recordings of heart rate, skin conductance, skin temperature, and electromyographic (EMG) activity were obtained during listening tasks of varying demand. Materials from the Dichotic Digits Test were used to modulate task demand. The three levels of task demand were single digits presented to one ear (low-demand reference condition), single digits presented simultaneously to both ears (medium demand), and a series of two digits presented simultaneously to both ears (high demand). Participants were asked to repeat all the digits they heard, while psychophysiological activity was recorded simultaneously. Subjective ratings of task load were obtained after each condition using the National Aeronautics and Space Administration Task Load Index questionnaire. Repeated-measures analyses of variance were completed for each measure using task demand and session as factors. Mean performance was higher than 96% for all listening tasks. There was no significant change in performance across listening conditions for any listener. There was, however, a significant increase in mean skin conductance and EMG activity as task demand increased. Heart rate and skin temperature did not change significantly. There was no strong association between subjective and psychophysiological measures, but all participants with mean normalized effort ratings of greater than 4.5 (i.e., effort increased by a factor of at least 4.5) showed significant changes in skin conductance. Even in the absence of substantial performance changes, listeners may experience changes in subjective and psychophysiological responses consistent with the activation of a stress response. Skin conductance appears to be the most promising measure for evaluating individual changes in psychophysiological responses during listening tasks. American Academy of Audiology.

Conflict monitoring and adjustment in the task-switching paradigm under different memory load conditions: an ERP/sLORETA analysis.

PubMed

Deng, Yuqin; Wang, Yan; Ding, Xiaoqian; Tang, Yi-Yuan

2015-02-11

The aim of the present study was to examine electrophysiological and behavioral changes caused by different memory loads in a task-switching paradigm. A total of 31 healthy individuals were subjected to a task, in which the stimulus-response reversal paradigm was combined with the task-switching paradigm. The event-related potentials were recorded and the N2 component, an index of conflict processing, was measured. In addition, the neural sources of N2 were further analyzed by standardized low-resolution brain electromagnetic tomography. The event-related potential results showed that high memory load triggered a higher N2 mean amplitude. Moreover, the standardized low-resolution brain electromagnetic tomography data showed that high memory load caused an increase in current densities at the anterior cingulate cortex and the prefrontal cortex in the task-switching paradigm. In summary, our findings provide electrophysiological evidence to interpret possible influences of memory loads on conflict monitoring and modulation during the task switching. These results imply that the working memory load overrules the influence of task-switching performance on the intensification of cognitive control.

[Effects of long term mental arithmetic on physiological parameters, subjective indices and task performances].

PubMed

Yamada, Shimpei; Miyake, Shinji

2007-03-01

This study examined the effects of long term mental arithmetic on physiological parameters, subjective indices and task performances to investigate the psychophysiological changes induced by mental tasks. Fifteen male university students performed six successive trials of a ten-minute mental arithmetic task. They took a five-minute resting period before and after the tasks. CFF (Critical Flicker Fusion frequency) and subjective fatigue scores using a visual analog scale, POMS (Profiles of Mood States) and SFF (Subjective Feelings of Fatigue) were obtained after each task and resting period. The voices of participants who were instructed to speak five Japanese vowels ('a', 'i', 'u', 'e', 'o') were recorded after each block to investigate a chaotic property of vocal signals that is reported to be changed by fatigue. Subjective workload ratings were also obtained by the NASA-TLX (National Aeronautics and Space Administration-Task Load Index) after the task. Physiological signals of ECG (Electrocardiogram), PTG (Photoelectric Plethysmogram), SCL (Skin Conductance Level), TBV (Tissue Blood Volume) and Respiration were recorded for all experimental blocks. The number of answers, correct rates and average levels of task difficulty for each ten-minute task were used as task performance indices. In this experiment, the task performance did not decrease, whereas subjective fatigue increased. Activation of the sympathetic nervous system was suggested by physiological parameters.

The Stationary-Gaze Task Should Not Be Systematically Used as the Control Task in Studies of Postural Control.

PubMed

Bonnet, Cédrick T; Szaffarczyk, Sébastien

2017-01-01

In studies of postural control, a control task is often used to understand significant effects obtained with experimental manipulations. This task should be the easiest task and (therefore) engage the lowest behavioral variability and cognitive workload. Since 1983, the stationary-gaze task is considered as the most relevant control task. Instead, the authors expected that free looking at small targets (white paper or images; visual angle: 12°) could be an easier task. To verify this assumption, 16 young individuals performed stationary-gaze, white-panel, and free-viewing 12° tasks in steady and relaxed stances. The stationary-gaze task led to significantly higher cognitive workload (mean score in the National Aeronotics and Space Administration Task Load Index questionnaire), higher interindividual body (head, neck, and lower back) linear variability, and higher interindividual body angular variability-not systematically yet-than both other tasks. There was more cognitive workload in steady than relaxed stances. The authors also tested if a free-viewing 24° task could lead to greater angular displacement, and hence greater body sway, than could the other tasks in relaxed stance. Unexpectedly, the participants mostly moved their eyes and not their body in this task. In the discussion, the authors explain why the stationary-gaze task may not be an ideal control task and how to choose this neutral task.

[Delegation of medico-administrative tasks : what do medical interns and secretaries think?

PubMed

Castioni, Julien; Hagenbuch, Angélique; Tâche, Johann; Cappai, Milva; Jovanovic, Milica; Sartori, Claudio

2017-11-22

The hospital activity of physicians in training mainly consists in direct contacts with patients, tasks indirectly linked to patients such as administration, as well as clinical and theoretical training. In our era of digitalization, an important administrative work load without any added medical value fills their daily chores. In parallel activities of medical secretaries are getting more partitioned, with their desks situated far from physicians' and tasks often limited to finalizing discharge letters. Added to multiple overtime, this reduces physicians' and secretaries' work satisfaction. This article describes the context and development of delegating medico-administrative tasks to secretaries in our department of internal medicine.

Individual Differences at High Perceptual Load: The Relation between Trait Anxiety and Selective Attention

PubMed Central

Sadeh, Naomi; Bredemeier, Keith

2010-01-01

Attentional control theory (Eysenck et al., 2007) posits that taxing attentional resources impairs performance efficiency in anxious individuals. This theory, however, does not explicitly address if or how the relation between anxiety and attentional control depends upon the perceptual demands of the task at hand. Consequently, the present study examined the relation between trait anxiety and task performance using a perceptual load task (Maylor & Lavie, 1998). Sixty-eight male college students completed a visual search task that indexed processing of irrelevant distractors systematically across four levels of perceptual load. Results indicated that anxiety was related to difficulty suppressing the behavioral effects of irrelevant distractors (i.e., decreased reaction time efficiency) under high, but not low, perceptual loads. In contrast, anxiety was not associated with error rates on the task. These findings are consistent with the prediction that anxiety is associated with impairments in performance efficiency under conditions that tax attentional resources. PMID:21547776

Individual differences at high perceptual load: the relation between trait anxiety and selective attention.

PubMed

Sadeh, Naomi; Bredemeier, Keith

2011-06-01

Attentional control theory (Eysenck et al., 2007) posits that taxing attentional resources impairs performance efficiency in anxious individuals. This theory, however, does not explicitly address if or how the relation between anxiety and attentional control depends upon the perceptual demands of the task at hand. Consequently, the present study examined the relation between trait anxiety and task performance using a perceptual load task (Maylor & Lavie, 1998). Sixty-eight male college students completed a visual search task that indexed processing of irrelevant distractors systematically across four levels of perceptual load. Results indicated that anxiety was related to difficulty suppressing the behavioural effects of irrelevant distractors (i.e., decreased reaction time efficiency) under high, but not low, perceptual loads. In contrast, anxiety was not associated with error rates on the task. These findings are consistent with the prediction that anxiety is associated with impairments in performance efficiency under conditions that tax attentional resources.

Increasing Working Memory Load Reduces Processing of Cross-Modal Task-Irrelevant Stimuli Even after Controlling for Task Difficulty and Executive Capacity

PubMed Central

Simon, Sharon S.; Tusch, Erich S.; Holcomb, Phillip J.; Daffner, Kirk R.

2016-01-01

The classic account of the load theory (LT) of attention suggests that increasing cognitive load leads to greater processing of task-irrelevant stimuli due to competition for limited executive resource that reduces the ability to actively maintain current processing priorities. Studies testing this hypothesis have yielded widely divergent outcomes. The inconsistent results may, in part, be related to variability in executive capacity (EC) and task difficulty across subjects in different studies. Here, we used a cross-modal paradigm to investigate whether augmented working memory (WM) load leads to increased early distracter processing, and controlled for the potential confounders of EC and task difficulty. Twenty-three young subjects were engaged in a primary visual WM task, under high and low load conditions, while instructed to ignore irrelevant auditory stimuli. Demands of the high load condition were individually titrated to make task difficulty comparable across subjects with differing EC. Event-related potentials (ERPs) were used to measure neural activity in response to stimuli presented in both the task relevant modality (visual) and task-irrelevant modality (auditory). Behavioral results indicate that the load manipulation and titration procedure of the primary visual task were successful. ERPs demonstrated that in response to visual target stimuli, there was a load-related increase in the posterior slow wave, an index of sustained attention and effort. Importantly, under high load, there was a decrease of the auditory N1 in response to distracters, a marker of early auditory processing. These results suggest that increased WM load is associated with enhanced attentional engagement and protection from distraction in a cross-modal setting, even after controlling for task difficulty and EC. Our findings challenge the classic LT and offer support for alternative models. PMID:27536226

Increasing Working Memory Load Reduces Processing of Cross-Modal Task-Irrelevant Stimuli Even after Controlling for Task Difficulty and Executive Capacity.

PubMed

Simon, Sharon S; Tusch, Erich S; Holcomb, Phillip J; Daffner, Kirk R

2016-01-01

The classic account of the load theory (LT) of attention suggests that increasing cognitive load leads to greater processing of task-irrelevant stimuli due to competition for limited executive resource that reduces the ability to actively maintain current processing priorities. Studies testing this hypothesis have yielded widely divergent outcomes. The inconsistent results may, in part, be related to variability in executive capacity (EC) and task difficulty across subjects in different studies. Here, we used a cross-modal paradigm to investigate whether augmented working memory (WM) load leads to increased early distracter processing, and controlled for the potential confounders of EC and task difficulty. Twenty-three young subjects were engaged in a primary visual WM task, under high and low load conditions, while instructed to ignore irrelevant auditory stimuli. Demands of the high load condition were individually titrated to make task difficulty comparable across subjects with differing EC. Event-related potentials (ERPs) were used to measure neural activity in response to stimuli presented in both the task relevant modality (visual) and task-irrelevant modality (auditory). Behavioral results indicate that the load manipulation and titration procedure of the primary visual task were successful. ERPs demonstrated that in response to visual target stimuli, there was a load-related increase in the posterior slow wave, an index of sustained attention and effort. Importantly, under high load, there was a decrease of the auditory N1 in response to distracters, a marker of early auditory processing. These results suggest that increased WM load is associated with enhanced attentional engagement and protection from distraction in a cross-modal setting, even after controlling for task difficulty and EC. Our findings challenge the classic LT and offer support for alternative models.

Sleep restriction and cognitive load affect performance on a simulated marksmanship task.

PubMed

Smith, Carl D; Cooper, Adam D; Merullo, Donna J; Cohen, Bruce S; Heaton, Kristin J; Claro, Pedro J; Smith, Tracey

2017-11-24

Sleep restriction degrades cognitive and motor performance, which can adversely impact job performance and increase the risk of accidents. Military personnel are prone to operating under sleep restriction, and previous work suggests that military marksmanship may be negatively affected under such conditions. Results of these studies, however, are mixed and have often incorporated additional stressors (e.g. energy restriction) beyond sleep restriction. Moreover, few studies have investigated how the degree of difficulty of a marksmanship task impacts performance following sleep restriction. The purpose of the current experiment was to study the effects of sleep restriction on marksmanship while minimizing the potential influence of other forms of stress. A friend-foe discrimination challenge with greater or lesser degrees of complexity (high versus low load) was used as the primary marksmanship task. Active duty Soldiers were recruited, and allowed 2 h of sleep every 24 h over a 72-h testing period. Marksmanship tasks, cognitive assessment metrics and the NASA-Task Load Index were administered daily. Results indicated that reaction times to shoot foe targets and signal friendly targets slowed over time. In addition, the ability to correctly discriminate between friend and foe targets significantly decreased in the high-cognitive-load condition over time despite shot accuracy remaining stable. The NASA-Task Load Index revealed that, although marksmanship performance degraded, participants believed their performance did not change over time. These results further characterize the consequences of sleep restriction on marksmanship performance and the perception of performance, and reinforce the importance of adequate sleep among service members when feasible. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

NASA Task Load Index (TLX). Volume 1.0; Paper and Pencil Package

NASA Technical Reports Server (NTRS)

Hart, Sandra G.

1986-01-01

This booklet contains the materials necessary to collect subjective workload assessments with the NASA Task Load Index. This procedure for collecting workload ratings was developed by the Human Performance Group at NASA Ames Research Center during a three year research effort that involved more than 40 laboratory. simulation. and inflight experiments. Although the technique is still undergoing evaluation. this booklet is being distributed to allow other researchers to use it in their own experiments. Comments or suggestions about the procedure would be greatly appreciated. This package is intended to fill a "nuts and bolts" function of describing the procedure. A bibliography provides background information about previous empirical findings and the logic that supports the procedure.

Assessing physician job satisfaction and mental workload.

PubMed

Boultinghouse, Oscar W; Hammack, Glenn G; Vo, Alexander H; Dittmar, Mary Lynne

2007-12-01

Physician job satisfaction and mental workload were evaluated in a pilot study of five physicians engaged in a telemedicine practice at The University of Texas Medical Branch at Galveston Electronic Health Network. Several previous studies have examined physician satisfaction with specific telemedicine applications; however, few have attempted to identify the underlying factors that contribute to physician satisfaction or lack thereof. One factor that has been found to affect well-being and functionality in the workplace-particularly with regard to human interaction with complex systems and tasks as seen in telemedicine-is mental workload. Workload is generally defined as the "cost" to a person for performing a complex task or tasks; however, prior to this study, it was unexplored as a variable that influences physician satisfaction. Two measures of job satisfaction were used: The Job Descriptive Index and the Job In General scales. Mental workload was evaluated by means of the National Aeronautics and Space Administration Task Load Index. The measures were administered by means of Web-based surveys and were given twice over a 6-month period. Nonparametric statistical analyses revealed that physician job satisfaction was generally high relative to that of the general population and other professionals. Mental workload scores associated with the practice of telemedicine in this environment are also high, and appeared stable over time. In addition, they are commensurate with scores found in individuals practicing tasks with elevated information-processing demands, such as quality control engineers and air traffic controllers. No relationship was found between the measures of job satisfaction and mental workload.

Effects of Low- Versus High-Fidelity Simulations on the Cognitive Burden and Performance of Entry-Level Paramedicine Students: A Mixed-Methods Comparison Trial Using Eye-Tracking, Continuous Heart Rate, Difficulty Rating Scales, Video Observation and Interviews.

PubMed

Mills, Brennen W; Carter, Owen B-J; Rudd, Cobie J; Claxton, Louise A; Ross, Nathan P; Strobel, Natalie A

2016-02-01

High-fidelity simulation-based training is often avoided for early-stage students because of the assumption that while practicing newly learned skills, they are ill suited to processing multiple demands, which can lead to "cognitive overload" and poorer learning outcomes. We tested this assumption using a mixed-methods experimental design manipulating psychological immersion. Thirty-nine randomly assigned first-year paramedicine students completed low- or high-environmental fidelity simulations [low-environmental fidelity simulations (LF(en)S) vs. high-environmental fidelity simulation (HF(en)S)] involving a manikin with obstructed airway (SimMan3G). Psychological immersion and cognitive burden were determined via continuous heart rate, eye tracking, self-report questionnaire (National Aeronautics and Space Administration Task Load Index), independent observation, and postsimulation interviews. Performance was assessed by successful location of obstruction and time-to-termination. Eye tracking confirmed that students attended to multiple, concurrent stimuli in HF(en)S and interviews consistently suggested that they experienced greater psychological immersion and cognitive burden than their LF(en)S counterparts. This was confirmed by significantly higher mean heart rate (P < 0.001) and National Aeronautics and Space Administration Task Load Index mental demand (P < 0.05). Although group allocation did not influence the proportion of students who ultimately revived the patient (58% vs. 30%, P < 0.10), the HF(en)S students did so significantly more quickly (P < 0.01). The LF(en)S students had low immersion resulting in greater assessment anxiety. High-environmental fidelity simulation engendered immersion and a sense of urgency in students, whereas LF(en)S created assessment anxiety and slower performance. We conclude that once early-stage students have learned the basics of a clinical skill, throwing them in the "deep end" of high-fidelity simulation creates significant additional cognitive burden but this has considerable educational merit.

Effects of transdermally administered nicotine on aspects of attention, task load, and mood in women and men.

PubMed

Trimmel, Michael; Wittberger, Susanne

2004-07-01

This double-blind placebo-controlled study was conducted to determine nicotine effects on diverse types of attentional performance, task load, and mood considering sex effects as suggested by animal studies. Twelve smokers, 12 deprived smokers and 12 nonsmokers (6 females, 6 males in each group) were investigated. Participants were treated either by 5 mg/16 h nicotine patches (Nicorette) or placebo. Effects of treatment were examined by a computerized attention-test battery; mood was assessed by the Berliner-Alltagssprachliches-Stimmungs-Inventar and task load by the NASA Task Load Index (NASA-TLX). Results showed that nicotine significantly increased the number of hits and decreased reaction time (RT) in the vigilance task. In the selective attention task combined with irrelevant speech as background noise, nicotine enhanced rate of hits. Although it was indicated that nicotine leads to a generally higher accuracy in attention tasks, response time of visual search was prolonged, contradicting a universal facilitation by nicotine. Participants experienced mental demand and temporal demand lower and rated alertness higher when in the nicotine condition. These effects were independent of smoking status, indicating "true" nicotine effects. Females took significant advantage of nicotine in the vigilance task, reaching the performance level of males, accompanied by a higher rated alertness. Results indicate task- and sex-dependent nicotine effects.

Grip force and force sharing in two different manipulation tasks with bottles.

PubMed

Cepriá-Bernal, Javier; Pérez-González, Antonio; Mora, Marta C; Sancho-Bru, Joaquín L

2017-07-01

Grip force and force sharing during two activities of daily living were analysed experimentally in 10 right-handed subjects. Four different bottles, filled to two different levels, were manipulated for two tasks: transporting and pouring. Each test subject's hand was instrumented with eight thin wearable force sensors. The grip force and force sharing were significantly different for each bottle model. Increasing the filling level resulted in an increase in grip force, but the ratio of grip force to load force was higher for lighter loads. The task influenced the force sharing but not the mean grip force. The contributions of the thumb and ring finger were higher in the pouring task, whereas the contributions of the palm and the index finger were higher in the transport task. Mean force sharing among fingers was 30% for index, 29% for middle, 22% for ring and 19% for little finger. Practitioner Summary: We analysed grip force and force sharing in two manipulation tasks with bottles: transporting and pouring. The objective was to understand the effects of the bottle features, filling level and task on the contribution of different areas of the hand to the grip force. Force sharing was different for each task and the bottles features affected to both grip force and force sharing.

NASA Task Load Index (TLX). Volume 1.0; Computerized Version

NASA Technical Reports Server (NTRS)

Hart, Sandra G.

1986-01-01

This booklet and the accompanying diskette contain the materials necessary to collect subjective workload assessments with the NASA Task Load Index on IBM PC compatible microcomputers. This procedure for collecting workload ratings was developed by the Human Performance Group at NASA Ames Research Center during a three year research effort that involved more than 40 laboratory, simulation, and inflight experiments Although the technique is still undergoing evaluation, this package is being distributed to allow other researchers to use it in their own experiments Comments or suggestions about the procedure would be greatly appreciated This package is intended to fill a "nuts and bolts" function of describing the procedure. A bibliography provides background information about previous empirical findings and the logic that supports the procedure.

Cardiac data increase association between self-report and both expert ratings of task load and task performance in flight simulator tasks: An exploratory study.

PubMed

Lehrer, Paul; Karavidas, Maria; Lu, Shou-En; Vaschillo, Evgeny; Vaschillo, Bronya; Cheng, Andrew

2010-05-01

Seven professional airplane pilots participated in a one-session test in a Boeing 737-800 simulator. Mental workload for 18 flight tasks was rated by experienced test pilots (hereinafter called "expert ratings") and by study participants' self-report on NASA's Task Load Index (TLX) scale. Pilot performance was rated by a check pilot. The standard deviation of R-R intervals (SDNN) significantly added 3.7% improvement over the TLX in distinguishing high from moderate-load tasks and 2.3% improvement in distinguishing high from combined moderate and low-load tasks. Minimum RRI in the task significantly discriminated high- from medium- and low-load tasks, but did not add significant predictive variance to the TLX. The low-frequency/high-frequency (LF:HF) RRI ratio based on spectral analysis of R-R intervals, and ventricular relaxation time were each negatively related to pilot performance ratings independently of TLX values, while minimum and average RRI were positively related, showing added contribution of these cardiac measures for predicting performance. Cardiac results were not affected by controlling either for respiration rate or motor activity assessed by accelerometry. The results suggest that cardiac assessment can be a useful addition to self-report measures for determining flight task mental workload and risk for performance decrements. Replication on a larger sample is needed to confirm and extend the results. Copyright 2010 Elsevier B.V. All rights reserved.

Mental workload during brain-computer interface training.

PubMed

Felton, Elizabeth A; Williams, Justin C; Vanderheiden, Gregg C; Radwin, Robert G

2012-01-01

It is not well understood how people perceive the difficulty of performing brain-computer interface (BCI) tasks, which specific aspects of mental workload contribute the most, and whether there is a difference in perceived workload between participants who are able-bodied and disabled. This study evaluated mental workload using the NASA Task Load Index (TLX), a multi-dimensional rating procedure with six subscales: Mental Demands, Physical Demands, Temporal Demands, Performance, Effort, and Frustration. Able-bodied and motor disabled participants completed the survey after performing EEG-based BCI Fitts' law target acquisition and phrase spelling tasks. The NASA-TLX scores were similar for able-bodied and disabled participants. For example, overall workload scores (range 0-100) for 1D horizontal tasks were 48.5 (SD = 17.7) and 46.6 (SD 10.3), respectively. The TLX can be used to inform the design of BCIs that will have greater usability by evaluating subjective workload between BCI tasks, participant groups, and control modalities. Mental workload of brain-computer interfaces (BCI) can be evaluated with the NASA Task Load Index (TLX). The TLX is an effective tool for comparing subjective workload between BCI tasks, participant groups (able-bodied and disabled), and control modalities. The data can inform the design of BCIs that will have greater usability.

Goal equivalent manifold analysis of task performance in non-specific LBP and healthy subjects during repetitive trunk movement: Effect of load, velocity, symmetry.

PubMed

Chehrehrazi, Mahshid; Sanjari, Mohammad Ali; Mokhtarinia, Hamid Reza; Jamshidi, Ali Ashraf; Maroufi, Nader; Parnianpour, Mohamad

2017-01-01

Motor abundance allows reliability of motor performance despite its variability. The nature of this variability provides important information on the flexibility of control strategies. This feature of control may be affected by low back pain (LPB) and trunk flexion/extension conditions. Goal equivalent manifold (GEM) analysis was used to quantify the ability to exploit motor abundance during repeated trunk flexion/extension in healthy individuals and people with chronic non-specific LBP (CNSLBP). Kinematic data were collected from 22 healthy volunteers and 22 CNSLBP patients during metronomically timed, repeated trunk flexion/extension in three conditions of symmetry, velocity, and loading; each at two levels. A goal function for the task was defined as maintaining a constant movement time at each cycle. Given the GEM, flexibility index and performance index were calculated respectively as amounts of goal-equivalent variability and the ratio of goal-equivalent to non-goal-equivalent variability. CNSLBP group was as similar as healthy individuals in both flexibility index (p=0.41) and performance index (p=0.24). Performance index was higher in asymmetric (p<0.001), high velocity (p<0.001), and loaded (p=0.006) conditions. Performance and flexibility in using motor abundance were influenced by repeated trunk flexion/extension conditions. However, these measures were not significantly affected by CNSLBP. Copyright © 2016 Elsevier B.V. All rights reserved.

Executive functioning in preschool children: performance on A-not-B and other delayed response format tasks.

PubMed

Espy, K A; Kaufmann, P M; McDiarmid, M D; Glisky, M L

1999-11-01

The A-not-B (AB) task has been hypothesized to measure executive/frontal lobe function; however, the developmental and measurement characteristics of this task have not been investigated. Performances on AB and comparison tasks adapted from developmental and neuroscience literature was examined in 117 preschool children (ages 23-66 months). Age significantly predicted performance on AB, Delayed Alternation, Spatial Reversal, Color Reversal, and Self-Control tasks. A four-factor analytic model best fit task performance data. AB task indices loaded on two factors with measures from the Self-Control and Delayed Alternation tasks, respectively. AB indices did not load with those from the reversal tasks despite similarities in task administration and presumed cognitive demand (working memory). These results indicate that AB is sensitive to individual differences in age-related performance in preschool children and suggest that AB performance is related to both working memory and inhibition processes in this age range.

Physician activity during outpatient visits and subjective workload.

PubMed

Calvitti, Alan; Hochheiser, Harry; Ashfaq, Shazia; Bell, Kristin; Chen, Yunan; El Kareh, Robert; Gabuzda, Mark T; Liu, Lin; Mortensen, Sara; Pandey, Braj; Rick, Steven; Street, Richard L; Weibel, Nadir; Weir, Charlene; Agha, Zia

2017-05-01

We describe methods for capturing and analyzing EHR use and clinical workflow of physicians during outpatient encounters and relating activity to physicians' self-reported workload. We collected temporally-resolved activity data including audio, video, EHR activity, and eye-gaze along with post-visit assessments of workload. These data are then analyzed through a combination of manual content analysis and computational techniques to temporally align streams, providing a range of process measures of EHR usage, clinical workflow, and physician-patient communication. Data was collected from primary care and specialty clinics at the Veterans Administration San Diego Healthcare System and UCSD Health, who use Electronic Health Record (EHR) platforms, CPRS and Epic, respectively. Grouping visit activity by physician, site, specialty, and patient status enables rank-ordering activity factors by their correlation to physicians' subjective work-load as captured by NASA Task Load Index survey. We developed a coding scheme that enabled us to compare timing studies between CPRS and Epic and extract patient and visit complexity profiles. We identified similar patterns of EHR use and navigation at the 2 sites despite differences in functions, user interfaces and consequent coded representations. Both sites displayed similar proportions of EHR function use and navigation, and distribution of visit length, proportion of time physicians attended to EHRs (gaze), and subjective work-load as measured by the task load survey. We found that visit activity was highly variable across individual physicians, and the observed activity metrics ranged widely as correlates to subjective workload. We discuss implications of our study for methodology, clinical workflow and EHR redesign. Copyright © 2017 Elsevier Inc. All rights reserved.

Affect Response to Simulated Information Attack during Complex Task Performance

DTIC Science & Technology

2014-12-02

AND FRUSTRATION ........................ 42 FIGURE 27. TASK LOAD INDEX OF MENTAL DEMAND, TEMPORAL DEMAND, AND PHYSICAL DEMAND...situational awareness, affect, and trait characteristics interact with human performance during cyberspace attacks in the physical and information...Operator state was manipulated using emotional stimulation portrayed through the presentation of video segments. The effect of emotions on

Transfer of training in the development of intracorporeal suturing skill in medical student novices: a prospective randomized trial.

PubMed

Muresan, Claude; Lee, Tommy H; Seagull, Jacob; Park, Adrian E

2010-10-01

To help optimize the use of limited resources in trainee education, we developed a prospective randomized trial to determine the most effective means of teaching laparoscopic suturing to novices. Forty-one medical students received rudimentary instruction in intracorporeal suturing, then were pretested on a pig enterotomy model. They then were posttested after completion of 1 of 4 training arms: laparoscopic suturing, laparoscopic drills, open suturing, and virtual reality (VR) drills. Tests were scored for speed, accuracy, knot quality, and mental workload (National Aeronautics and Space Administration [NASA] Task Load Index). Paired t tests were used. Task time was improved in all groups except the VR group. Knot quality improved only in the open or laparoscopic suturing groups. Mental workload improved only for those practicing on a physical laparoscopic trainer. For novice trainees, the efficacy of VR training is questionable. In contrast, the other training methods had benefits in terms of time, quality, and perceived workload. Copyright © 2010 Elsevier Inc. All rights reserved.

Limitations of subjective cognitive load measures in simulation-based procedural training.

PubMed

Naismith, Laura M; Cheung, Jeffrey J H; Ringsted, Charlotte; Cavalcanti, Rodrigo B

2015-08-01

The effective implementation of cognitive load theory (CLT) to optimise the instructional design of simulation-based training requires sensitive and reliable measures of cognitive load. This mixed-methods study assessed relationships between commonly used measures of total cognitive load and the extent to which these measures reflected participants' experiences of cognitive load in simulation-based procedural skills training. Two groups of medical residents (n = 38) completed three questionnaires after participating in simulation-based procedural skills training sessions: the Paas Cognitive Load Scale; the NASA Task Load Index (TLX), and a cognitive load component (CLC) questionnaire we developed to assess total cognitive load as the sum of intrinsic load (how complex the task is), extraneous load (how the task is presented) and germane load (how the learner processes the task for learning). We calculated Pearson's correlation coefficients to assess agreement among these instruments. Group interviews explored residents' perceptions about how the simulation sessions contributed to their total cognitive load. Interviews were audio-recorded, transcribed and subjected to qualitative content analysis. Total cognitive load scores differed significantly according to the instrument used to assess them. In particular, there was poor agreement between the Paas Scale and the TLX. Quantitative and qualitative findings supported intrinsic cognitive load as synonymous with mental effort (Paas Scale), mental demand (TLX) and task difficulty and complexity (CLC questionnaire). Additional qualitative themes relating to extraneous and germane cognitive loads were not reflected in any of the questionnaires. The Paas Scale, TLX and CLC questionnaire appear to be interchangeable as measures of intrinsic cognitive load, but not of total cognitive load. A more complete understanding of the sources of extraneous and germane cognitive loads in simulation-based training contexts is necessary to determine how best to measure and assess their effects on learning and performance outcomes. © 2015 John Wiley & Sons Ltd.

Cognitive Load in Voice Therapy Carry-Over Exercises.

PubMed

Iwarsson, Jenny; Morris, David Jackson; Balling, Laura Winther

2017-01-01

The cognitive load generated by online speech production may vary with the nature of the speech task. This article examines 3 speech tasks used in voice therapy carry-over exercises, in which a patient is required to adopt and automatize new voice behaviors, ultimately in daily spontaneous communication. Twelve subjects produced speech in 3 conditions: rote speech (weekdays), sentences in a set form, and semispontaneous speech. Subjects simultaneously performed a secondary visual discrimination task for which response times were measured. On completion of each speech task, subjects rated their experience on a questionnaire. Response times from the secondary, visual task were found to be shortest for the rote speech, longer for the semispontaneous speech, and longest for the sentences within the set framework. Principal components derived from the subjective ratings were found to be linked to response times on the secondary visual task. Acoustic measures reflecting fundamental frequency distribution and vocal fold compression varied across the speech tasks. The results indicate that consideration should be given to the selection of speech tasks during the process leading to automation of revised speech behavior and that self-reports may be a reliable index of cognitive load.

Population-based learning of load balancing policies for a distributed computer system

NASA Technical Reports Server (NTRS)

Mehra, Pankaj; Wah, Benjamin W.

1993-01-01

Effective load-balancing policies use dynamic resource information to schedule tasks in a distributed computer system. We present a novel method for automatically learning such policies. At each site in our system, we use a comparator neural network to predict the relative speedup of an incoming task using only the resource-utilization patterns obtained prior to the task's arrival. Outputs of these comparator networks are broadcast periodically over the distributed system, and the resource schedulers at each site use these values to determine the best site for executing an incoming task. The delays incurred in propagating workload information and tasks from one site to another, as well as the dynamic and unpredictable nature of workloads in multiprogrammed multiprocessors, may cause the workload pattern at the time of execution to differ from patterns prevailing at the times of load-index computation and decision making. Our load-balancing policy accommodates this uncertainty by using certain tunable parameters. We present a population-based machine-learning algorithm that adjusts these parameters in order to achieve high average speedups with respect to local execution. Our results show that our load-balancing policy, when combined with the comparator neural network for workload characterization, is effective in exploiting idle resources in a distributed computer system.

Ergonomic design and evaluation of new surgical scissors.

PubMed

Shimomura, Yoshihiro; Shirakawa, Hironori; Sekine, Masashi; Katsuura, Tetsuo; Igarashi, Tatsuo

2015-01-01

The purpose of this study is to design a new surgical scissors handle and determine its effectiveness with various usability indices. A new scissors handle was designed that retains the professional grip but has the shapes of the eye rings modified to fit the thumb and ring finger and finger rests for the index and little finger. The newly designed scissors and traditional scissors were compared by electromyography, subjective evaluation and task performance in experiments using cutting and peeling tasks. The newly designed scissors reduced muscle load in both hand during cutting by the closing action, and reduced the muscle load in the left hand during peeling by the opening action through active use of the right hand. In evaluation by surgeons, task performance improved in addition to the decrease in muscle load. The newly designed scissors used in this study demonstrated high usability. A new scissors handle was designed that has the eye rings modified to fit the thumb and ring finger. The newly designed scissors reduced muscle load and enabled active use of the right hand. In evaluation by surgeons, task performance improved in addition to the decrease in muscle load.

The effects of control order, feedback, practice, and input device on tracking performance and perceived workload

NASA Technical Reports Server (NTRS)

Hancock, P. A.; Robinson, M. A.

1989-01-01

The present experiment examined the influence of several task-related factors on tracking performance and concomitant workload. The manipulated factors included tracking order, the presence or absence of knowledge of performance, and the control device. Summed root mean square error (rmse) and perceived workload were measured at the termination of each trial. Perceived workload was measured using the NASA Task Load Index (TLX) and the Subjective Workload Assessment Technique (SWAT). Results indicated a large and expected effect for track order on both performance and the perception of load. In general, trackball input was more accurate and judged for lower load than input using a mouse. The presence or absence of knowledge of performance had little effect on either performance or workload. There were a number of interactions between factors shown in performance that were mirrored by perceived workload scores. Results from each workload scale were equivalent in terms of sensitivity to task manipulations. The pattern of results affirm the utility of these workload measures in assessing the imposed load of multiple task-related variables.

Effects of Mental Load and Fatigue on Steady-State Evoked Potential Based Brain Computer Interface Tasks: A Comparison of Periodic Flickering and Motion-Reversal Based Visual Attention.

PubMed

Xie, Jun; Xu, Guanghua; Wang, Jing; Li, Min; Han, Chengcheng; Jia, Yaguang

Steady-state visual evoked potentials (SSVEP) based paradigm is a conventional BCI method with the advantages of high information transfer rate, high tolerance to artifacts and the robust performance across users. But the occurrence of mental load and fatigue when users stare at flickering stimuli is a critical problem in implementation of SSVEP-based BCIs. Based on electroencephalography (EEG) power indices α, θ, θ + α, ratio index θ/α and response properties of amplitude and SNR, this study quantitatively evaluated the mental load and fatigue in both of conventional flickering and the novel motion-reversal visual attention tasks. Results over nine subjects revealed significant mental load alleviation in motion-reversal task rather than flickering task. The interaction between factors of "stimulation type" and "fatigue level" also illustrated the motion-reversal stimulation as a superior anti-fatigue solution for long-term BCI operation. Taken together, our work provided an objective method favorable for the design of more practically applicable steady-state evoked potential based BCIs.

Pupillometry as a Tool to Study Expertise in Medicine

ERIC Educational Resources Information Center

Szulewski, Adam; Kelton, Danielle; Howes, Daniel

2017-01-01

Background: Pupillometry has been studied as a physiological marker for quantifying cognitive load since the early 1960s. It has been established that small changes in pupillary size can provide an index of the cognitive load of an individual as he/she performs a mental task. The utility of pupillometry as a measure of expertise is less well…

Central load reduces peripheral processing: Evidence from incidental memory of background speech.

PubMed

Halin, Niklas; Marsh, John E; Sörqvist, Patrik

2015-12-01

Is there a trade-off between central (working memory) load and peripheral (perceptual) processing? To address this question, participants were requested to undertake an n-back task in one of two levels of central/cognitive load (i.e., 1-back or 2-back) in the presence of a to-be-ignored story presented via headphones. Participants were told to ignore the background story, but they were given a surprise memory test of what had been said in the background story, immediately after the n-back task was completed. Memory was poorer in the high central load (2-back) condition in comparison with the low central load (1-back) condition. Hence, when people compensate for higher central load, by increasing attentional engagement, peripheral processing is constrained. Moreover, participants with high working memory capacity (WMC) - with a superior ability for attentional engagement - remembered less of the background story, but only in the low central load condition. Taken together, peripheral processing - as indexed by incidental memory of background speech - is constrained when task engagement is high. © 2015 The Authors. Scandinavian Journal of Psychology published by Scandinavian Psychological Associations and John Wiley & Sons Ltd.

The effects of muscle vibration on anticipatory postural adjustments.

PubMed

Slijper, Harm; Latash, Mark L

2004-07-23

The current study investigated the influence of changes in sensory information related to postural stability on anticipatory postural adjustments (APAs) in standing subjects. Subjects performed fast arm movements and a load release task while standing on a stable force platform or on an unstable board. We manipulated sensory information through vibration of the Achilles tendons and additional finger touch (contact forces under 1 N). Changes in the background activity of leg, trunk, and arm muscles and displacements of the center of pressure (COP) were quantified within time intervals typical for APAs. In the arm movement task, leg and trunk muscles showed a significant drop in the APAs with finger touch, while the vibration and standing on the unstable board each led to an increase in the APA magnitude. In the load release task, ventral muscles decreased their APA activity with touch, while dorsal muscles showed increased inhibition during APAs. During vibration, dorsal and ventral muscles showed increased excitation and inhibition during APAs, respectively. An additional analysis of APAs at a joint level, has shown that in both tasks, an index related to the co-activation of agonist-antagonist muscle pairs (C-index) was modulated with touch, vibration, and stability particularly in leg muscles. Small changes in the other index related to reciprocal activation (R-index) were found only in trunk muscles. Light touch and vibration induced opposing changes in the C-index, suggesting their opposite effects on the stabilization of a reference point or vertical. We conclude that the central nervous system deploys patterns of adjustments in which increased co-contraction of distal muscles and reciprocal adjustments in trunk muscles are modified to ensure equilibrium under postural instability.

Effects of gamma-aminobutyric acid-modulating drugs on working memory and brain function in patients with schizophrenia.

PubMed

Menzies, Lara; Ooi, Cinly; Kamath, Shri; Suckling, John; McKenna, Peter; Fletcher, Paul; Bullmore, Ed; Stephenson, Caroline

2007-02-01

Cognitive impairment causes morbidity in schizophrenia and could be due to abnormalities of cortical interneurons using the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). To test the predictions that cognitive and brain functional responses to GABA-modulating drugs are correlated and abnormal in schizophrenia. Pharmacological functional magnetic resonance imaging study of 2 groups, each undergoing scanning 3 times, using an N-back working memory task, after placebo, lorazepam, or flumazenil administration. Eleven patients with chronic schizophrenia were recruited from a rehabilitation service, and 11 healthy volunteers matched for age, sex, and premorbid IQ were recruited from the local community. Intervention Participants received 2 mg of oral lorazepam, a 0.9-mg intravenous flumazenil bolus followed by a flumazenil infusion of 0.0102 mg/min, or oral and intravenous placebo. Working memory performance was summarized by the target discrimination index at several levels of difficulty. Increasing (or decreasing) brain functional activation in response to increasing task difficulty was summarized by the positive (or negative) load response. Lorazepam impaired performance and flumazenil enhanced it; these cognitive effects were more salient in schizophrenic patients. Functional magnetic resonance imaging demonstrated positive load response in a frontoparietal system and negative load response in the temporal and posterior cingulate regions; activation of the frontoparietal cortex was positively correlated with deactivation of the temporocingulate cortex. After placebo administration, schizophrenic patients had abnormally attenuated activation of the frontoparietal cortex and deactivation of the temporocingulate cortex; this pattern was mimicked in healthy volunteers and exacerbated in schizophrenic patients by lorazepam. However, in schizophrenic patients, flumazenil enhanced deactivation of the temporocingulate and activation of the anterior cingulate cortices. The GABA-modulating drugs differentially affect working memory performance and brain function in schizophrenia. Cognitive impairment in schizophrenia may reflect abnormal inhibitory function and could be treated by drugs targeting GABA neurotransmission.

Health literacy and task environment influence parents' burden for data entry on child-specific health information: randomized controlled trial.

PubMed

Porter, Stephen C; Guo, Chao-Yu; Bacic, Janine; Chan, Eugenia

2011-01-26

Health care systems increasingly rely on patients' data entry efforts to organize and assist in care delivery through health information exchange. We sought to determine (1) the variation in burden imposed on parents by data entry efforts across paper-based and computer-based environments, and (2) the impact, if any, of parents' health literacy on the task burden. We completed a randomized controlled trial of parent-completed data entry tasks. Parents of children with attention deficit hyperactivity disorder (ADHD) were randomized based on the Test of Functional Health Literacy in Adults (TOFHLA) to either a paper-based or computer-based environment for entry of health information on their children. The primary outcome was the National Aeronautics and Space Administration Task Load Index (TLX) total weighted score. We screened 271 parents: 194 (71.6%) were eligible, and 180 of these (92.8%) constituted the study cohort. We analyzed 90 participants from each arm. Parents who completed information tasks on paper reported a higher task burden than those who worked in the computer environment: mean (SD) TLX scores were 22.8 (20.6) for paper and 16.3 (16.1) for computer. Assignment to the paper environment conferred a significant risk of higher task burden (F(1,178) = 4.05, P = .046). Adequate literacy was associated with lower task burden (decrease in burden score of 1.15 SD, P = .003). After adjusting for relevant child and parent factors, parents' TOFHLA score (beta = -.02, P = .02) and task environment (beta = .31, P = .03) remained significantly associated with task burden. A tailored computer-based environment provided an improved task experience for data entry compared to the same tasks completed on paper. Health literacy was inversely related to task burden.

[The appraisal of reliability and validity of subjective workload assessment technique and NASA-task load index].

PubMed

Xiao, Yuan-mei; Wang, Zhi-ming; Wang, Mian-zhen; Lan, Ya-jia

2005-06-01

To test the reliability and validity of two mental workload assessment scales, i.e. subjective workload assessment technique (SWAT) and NASA task load index (NASA-TLX). One thousand two hundred and sixty-eight mental workers were sampled from various kinds of occupations, such as scientific research, education, administration and medicine, etc, with randomized cluster sampling. The re-test reliability, split-half reliability, Cronbach's alpha coefficient and correlation coefficients between item score and total score were adopted to test the reliability. The test of validity included structure validity. The re-test reliability coefficients of these two scales and their items were ranged from 0.516 to 0.753 (P < 0.01), indicating the two scales had good re-test reliability; the split-half reliability of SWAT was 0.645, and its Cronbach's alpha coefficient was more than 0.80, all the correlation coefficients between its items score and total score were more than 0.70; as for NASA-TLX, both the split-half reliability and Cronbach's alpha coefficient were more than 0.80, the correlation coefficients between its items score and total score were all more than 0.60 (P < 0.01) except the item of performance. Both scales had good inner consistency. The Pearson correlation coefficient between the two scales was 0.492 (P < 0.01), implying the results of the two scales had good consistency. Factor analysis showed that the two scales had good structure validity. Both SWAT and NASA-TLX have good reliability and validity and may be used as a valid tool to assess mental workload in China after being revised properly.

Verifiable Task Assignment and Scheduling Controller

DTIC Science & Technology

2017-07-01

15 Figure 8. Summary of results for NASA -TLX overall workload and individual...using the NASA Task Load Index ( NASA -TLX; Hart & Staveland, 1988), which was completed using a computerized version of the questionnaire. The...filled out the NASA -TLX. Then prior to the second trial, participants were trained on how to use SPEC. SPEC training consisted of: an explanation of the

When loading working memory reduces distraction: behavioral and electrophysiological evidence from an auditory-visual distraction paradigm.

PubMed

SanMiguel, Iria; Corral, María-José; Escera, Carles

2008-07-01

The sensitivity of involuntary attention to top-down modulation was tested using an auditory-visual distraction task and a working memory (WM) load manipulation in subjects performing a simple visual classification task while ignoring contingent auditory stimulation. The sounds were repetitive standard tones (80%) and environmental novel sounds (20%). Distraction caused by the novel sounds was compared across a 1-back WM condition and a no-memory control condition, both involving the comparison of two digits. Event-related brain potentials (ERPs) to the sounds were recorded, and the N1/MMN (mismatch negativity), novelty-P3, and RON components were identified in the novel minus standard difference waveforms. Distraction was reduced in the WM condition, both behaviorally and as indexed by an attenuation of the late phase of the novelty-P3. The transient/change detection mechanism indexed by MMN was not affected by the WM manipulation. Sustained slow frontal and parietal waveforms related to WM processes were found on the standard ERPs. The present results indicate that distraction caused by irrelevant novel sounds is reduced when a WM component is involved in the task, and that this modulation by WM load takes place at a late state of the orienting response, all in all confirming that involuntary attention is under the control of top-down mechanisms. Moreover, as these results contradict predictions of the load theory of selective attention and cognitive control, it is suggested that the WM load effects on distraction depend on the nature of the distractor-target relationships.

Lie construction affects information storage under high memory load condition.

PubMed

Liu, Yuqiu; Wang, Chunjie; Jiang, Haibo; He, Hongjian; Chen, Feiyan

2017-01-01

Previous studies indicate that lying consumes cognitive resources, especially working memory (WM) resources. Considering the dual functions that WM might play in lying: holding the truth-related information and turning the truth into lies, the present study examined the relationship between the information storage and processing in the lie construction. To achieve that goal, a deception task based on the old/new recognition paradigm was designed, which could manipulate two levels of WM load (low-load task using 4 items and high-load task using 6 items) during the deception process. The analyses based on the amplitude of the contralateral delay activity (CDA), a proved index of the number of representations being held in WM, showed that the CDA amplitude was lower in the deception process than that in the truth telling process under the high-load condition. In contrast, under the low-load condition, no CDA difference was found between the deception and truth telling processes. Therefore, we deduced that the lie construction and information storage compete for WM resources; when the available WM resources cannot meet this cognitive demand, the WM resources occupied by the information storage would be consumed by the lie construction.

Lie construction affects information storage under high memory load condition

PubMed Central

Liu, Yuqiu; Wang, Chunjie; Jiang, Haibo; He, Hongjian; Chen, Feiyan

2017-01-01

Previous studies indicate that lying consumes cognitive resources, especially working memory (WM) resources. Considering the dual functions that WM might play in lying: holding the truth-related information and turning the truth into lies, the present study examined the relationship between the information storage and processing in the lie construction. To achieve that goal, a deception task based on the old/new recognition paradigm was designed, which could manipulate two levels of WM load (low-load task using 4 items and high-load task using 6 items) during the deception process. The analyses based on the amplitude of the contralateral delay activity (CDA), a proved index of the number of representations being held in WM, showed that the CDA amplitude was lower in the deception process than that in the truth telling process under the high-load condition. In contrast, under the low-load condition, no CDA difference was found between the deception and truth telling processes. Therefore, we deduced that the lie construction and information storage compete for WM resources; when the available WM resources cannot meet this cognitive demand, the WM resources occupied by the information storage would be consumed by the lie construction. PMID:28727794

Quantification of Load Dependent Brain Activity in Parametric N-Back Working Memory Tasks using Pseudo-continuous Arterial Spin Labeling (pCASL) Perfusion Imaging.

PubMed

Zou, Qihong; Gu, Hong; Wang, Danny J J; Gao, Jia-Hong; Yang, Yihong

2011-04-01

Brain activation and deactivation induced by N-back working memory tasks and their load effects have been extensively investigated using positron emission tomography (PET) and blood-oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI). However, the underlying mechanisms of BOLD fMRI are still not completely understood and PET imaging requires injection of radioactive tracers. In this study, a pseudo-continuous arterial spin labeling (pCASL) perfusion imaging technique was used to quantify cerebral blood flow (CBF), a well understood physiological index reflective of cerebral metabolism, in N-back working memory tasks. Using pCASL, we systematically investigated brain activation and deactivation induced by the N-back working memory tasks and further studied the load effects on brain activity based on quantitative CBF. Our data show increased CBF in the fronto-parietal cortices, thalamus, caudate, and cerebellar regions, and decreased CBF in the posterior cingulate cortex and medial prefrontal cortex, during the working memory tasks. Most of the activated/deactivated brain regions show an approximately linear relationship between CBF and task loads (0, 1, 2 and 3 back), although several regions show non-linear relationships (quadratic and cubic). The CBF-based spatial patterns of brain activation/deactivation and load effects from this study agree well with those obtained from BOLD fMRI and PET techniques. These results demonstrate the feasibility of ASL techniques to quantify human brain activity during high cognitive tasks, suggesting its potential application to assessing the mechanisms of cognitive deficits in neuropsychiatric and neurological disorders.

Intake of green tea inhibited increase of salivary chromogranin A after mental task stress loads

PubMed Central

2014-01-01

Background Green tea has become renowned for its health benefits. In this study, we investigated the anti-stress effect of two kinds of green tea against a mental stress task load. Methods Warm water, ordinary green tea (Sagara), and shaded white tea, which contains more amino acid components than Sagara, were used as test samples in a randomized cross-over design study. Eighteen students (nine male and nine female) participated in three experimental trials on different days at intervals of seven days. Saliva was collected before beverage intake and after performing the mental stress load tasks. Concentration of chromogranin A (CgA) in the saliva was used as an index of autonomic nervous system activity. Results CgA level increased after the mental tasks, but intake of green tea inhibited this increase; the anti-stress effect was even greater after consumption of shaded white tea. Intake of shaded white tea also lowered Total Mood Disturbance (TMD) score on the Profile of Mood States (POMS); subjects in this condition tended to perform more calculations in the arithmetic task than those in the warm water treatment condition. Conclusions Salivary CgA concentration levels increased after mental stress load tasks, but ingestion of green tea inhibited this increase. This anti-stress effect was larger after the consumption of shaded white tea than after Sagara. Shaded white tea intake also lowered TMD score (POMS) and tended to improve performance on an arithmetic task compared to warm water, suggesting that shaded white tea might also improve mood during and after mental stress load. PMID:25034805

Isometric Arm Strength and Subjective Rating of Upper Limb Fatigue in Two-Handed Carrying Tasks

PubMed Central

Li, Kai Way; Chiu, Wen-Sheng

2015-01-01

Sustained carrying could result in muscular fatigue of the upper limb. Ten male and ten female subjects were recruited for measurements of isometric arm strength before and during carrying a load for a period of 4 minutes. Two levels of load of carrying were tested for each of the male and female subjects. Exponential function based predictive equations for the isometric arm strength were established. The mean absolute deviations of these models in predicting the isometric arm strength were in the range of 3.24 to 17.34 N. Regression analyses between the subjective ratings of upper limb fatigue and force change index (FCI) for the carrying were also performed. The results indicated that the subjective rating of muscular fatigue may be estimated by multiplying the FCI with a constant. The FCI may, therefore, be adopted as an index to assess muscular fatigue for two-handed carrying tasks. PMID:25794159

Isometric arm strength and subjective rating of upper limb fatigue in two-handed carrying tasks.

PubMed

Li, Kai Way; Chiu, Wen-Sheng

2015-01-01

Sustained carrying could result in muscular fatigue of the upper limb. Ten male and ten female subjects were recruited for measurements of isometric arm strength before and during carrying a load for a period of 4 minutes. Two levels of load of carrying were tested for each of the male and female subjects. Exponential function based predictive equations for the isometric arm strength were established. The mean absolute deviations of these models in predicting the isometric arm strength were in the range of 3.24 to 17.34 N. Regression analyses between the subjective ratings of upper limb fatigue and force change index (FCI) for the carrying were also performed. The results indicated that the subjective rating of muscular fatigue may be estimated by multiplying the FCI with a constant. The FCI may, therefore, be adopted as an index to assess muscular fatigue for two-handed carrying tasks.

A randomized controlled study to establish the effect of articulating instruments on performance in single-incision laparoscopic surgery.

PubMed

Corker, Harry P; Singh, Pritam; Sodergren, Mikael H; Balaji, Sathyan; Kwasnicki, Richard M; Darzi, Ara W; Paraskeva, Paraskevas

2015-01-01

In single-incision laparoscopic surgery (SILS), operating through 1 incision presents ergonomic challenges. No consensus exists on whether articulating instruments (ARTs) may help. This study evaluated their effect on simulated SILS, hypothesizing that they would affect performance and workload. Surgeons were randomized to 2 straight instruments (STRs), 1 ART and 1 STR, or 2 ARTs. After baseline testing, 25 repetitions of the Fundamentals of Laparoscopic Surgery (FLS) peg-transfer (PEG) task and 5 repetitions of the short-hand for the FLS pattern-cutting task (CIRCLE) were performed. Primary outcomes were maximum FLS PEG scores, CIRCLE times and errors, and Imperial College Surgical Assessment Device hand motion analysis. National Aeronautics and Space Administration (NASA) Raw Task Load Index (RTLX) questionnaires evaluated a secondary outcome--workload. The trial took place in a simulated operating theater within the Academic Surgical Unit at St Mary's Hospital, London, UK. Eligible surgeons had completed at least 5 laparoscopic cases as a primary operator. Surgeons were stratified by laparoscopic experience into intermediate (less than 25 previous procedures as primary operator) or advanced (25 procedures or more). A total of 21 surgeons were recruited and randomized; 7 of them to each instrument combination group. All surgeons completed PEG, and 5 from each group completed CIRCLE. Groups' baseline PEG scores were similar (p = 0.625). STR-ART achieved higher maximum PEG scores than STR or ART did (median = 236 vs 198 vs 193, respectively, p = 0.002). Fastest CIRCLE times were similar (median = 190s vs 130s vs 186s, p = 0.129) as were minimum errors (median = 1 vs 2 vs 3, p = 0.101). For PEG, Imperial College Surgical Assessment Device demonstrated similar total path lengths (median = 12.3m vs 12.3m vs 16.0m, p = 0.545) and total numbers of movements (median = 89.6 vs 86.4 vs 171, p = 0.080). Groups' NASA Raw Task Load Index scores were similar (p = 0.708). Combining 1 STR and 1 ART improved SILS performance in the PEG task. Therefore, this may be the optimum instrument configuration for use within some clinical SILS applications. Copyright © 2014 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

The effect of non-visual working memory load on top-down modulation of visual processing

PubMed Central

Rissman, Jesse; Gazzaley, Adam; D'Esposito, Mark

2009-01-01

While a core function of the working memory (WM) system is the active maintenance of behaviorally relevant sensory representations, it is also critical that distracting stimuli are appropriately ignored. We used functional magnetic resonance imaging to examine the role of domain-general WM resources in the top-down attentional modulation of task-relevant and irrelevant visual representations. In our dual-task paradigm, each trial began with the auditory presentation of six random (high load) or sequentially-ordered (low load) digits. Next, two relevant visual stimuli (e.g., faces), presented amongst two temporally interspersed visual distractors (e.g., scenes), were to be encoded and maintained across a 7-sec delay interval, after which memory for the relevant images and digits was probed. When taxed by high load digit maintenance, participants exhibited impaired performance on the visual WM task and a selective failure to attenuate the neural processing of task-irrelevant scene stimuli. The over-processing of distractor scenes under high load was indexed by elevated encoding activity in a scene-selective region-of-interest relative to low load and passive viewing control conditions, as well as by improved long-term recognition memory for these items. In contrast, the load manipulation did not affect participants' ability to upregulate activity in this region when scenes were task-relevant. These results highlight the critical role of domain-general WM resources in the goal-directed regulation of distractor processing. Moreover, the consequences of increased WM load in young adults closely resemble the effects of cognitive aging on distractor filtering [Gazzaley et al., (2005) Nature Neuroscience 8, 1298-1300], suggesting the possibility of a common underlying mechanism. PMID:19397858

Improving pilot mental workload evaluation with combined measures.

PubMed

Wanyan, Xiaoru; Zhuang, Damin; Zhang, Huan

2014-01-01

Behavioral performance, subjective assessment based on NASA Task Load Index (NASA-TLX), as well as physiological measures indexed by electrocardiograph (ECG), event-related potential (ERP), and eye tracking data were used to assess the mental workload (MW) related to flight tasks. Flight simulation tasks were carried out by 12 healthy participants under different MW conditions. The MW conditions were manipulated by setting the quantity of flight indicators presented on the head-up display (HUD) in the cruise phase. In this experiment, the behavioral performance and NASA-TLX could reflect the changes of MW ideally. For physiological measures, the indices of heart rate variability (HRV), P3a, pupil diameter and eyelid opening were verified to be sensitive to MW changes. Our findings can be applied to the comprehensive evaluation of MW during flight tasks and the further quantitative classification.

Virtual surgical planning in endoscopic skull base surgery.

PubMed

Haerle, Stephan K; Daly, Michael J; Chan, Harley H L; Vescan, Allan; Kucharczyk, Walter; Irish, Jonathan C

2013-12-01

Skull base surgery (SBS) involves operative tasks in close proximity to critical structures in a complex three-dimensional (3D) anatomy. The aim was to investigate the value of virtual planning (VP) based on preoperative magnetic resonance imaging (MRI) for surgical planning in SBS and to compare the effects of virtual planning with 3D contours between the expert and the surgeon in training. Retrospective analysis. Twelve patients with manually segmented anatomical structures based on preoperative MRI were evaluated by eight surgeons in a randomized order using a validated National Aeronautics and Space Administration Task Load Index (NASA-TLX) questionnaire. Multivariate analysis revealed significant reduction of workload when using VP (P<.0001) compared to standard planning. Further, it showed that the experience level of the surgeon had a significant effect on the NASA-TLX differences (P<.05). Additional subanalysis did not reveal any significant findings regarding which type of surgeon benefits the most (P>.05). Preoperative anatomical segmentation with virtual surgical planning using contours in endoscopic SBS significantly reduces the workload for the expert and the surgeon in training. Copyright © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

The effect of two different electronic health record user interfaces on intensive care provider task load, errors of cognition, and performance.

PubMed

Ahmed, Adil; Chandra, Subhash; Herasevich, Vitaly; Gajic, Ognjen; Pickering, Brian W

2011-07-01

The care of critically ill patients generates large quantities of data. Increasingly, these data are presented to the provider within an electronic medical record. The manner in which data are organized and presented can impact on the ability of users to synthesis that data into meaningful information. The objective of this study was to test the hypothesis that novel user interfaces, which prioritize the display of high-value data to providers within system-based packages, reduce task load, and result in fewer errors of cognition compared with established user interfaces that do not. Randomized crossover study. Academic tertiary referral center. Attending, resident and fellow critical care physicians. Novel health care record user interface. Subjects randomly assigned to either a standard electronic medical record or a novel user interface, were asked to perform a structured task. The task required the subjects to use the assigned electronic environment to review the medical record of an intensive care unit patient said to be actively bleeding for data that formed the basis of answers to clinical questions posed in the form of a structured questionnaire. The primary outcome was task load, measured using the paper version of the NASA-task load index. Secondary outcome measures included time to task completion, number of errors of cognition measured by comparison of subject to post hoc gold standard questionnaire responses, and the quantity of information presented to subjects by each environment. Twenty subjects completed the task on eight patients, resulting in 160 patient-provider encounters (80 in each group). The standard electronic medical record contained a much larger data volume with a median (interquartile range) number of data points per patient of 1008 (895-1183) compared with 102 (77-112) contained within the novel user interface. The median (interquartile range) NASA-task load index values were 38.8 (32-45) and 58 (45-65) for the novel user interface compared with the standard electronic medical record (p < .001). The median (interquartile range) times in seconds taken to complete the task for four consecutive patients were 93 (57-132), 60 (48-71), 68 (48-80), and 54 (42-64) for the novel user interface compared with 145 (109-201), 125 (113-162), 129 (100-145), and 112 (92-123) for the standard interface (p < .0001), respectively. The median (interquartile range) number of errors per provider was 0.5 (0-1) and two (0.25-3) for the novel user interface and standard electronic medical record interface, respectively (p = .007). A novel user interface was designed based on the information needs of intensive care unit providers with a specific goal of development being the reduction of task load and errors of cognition associated with filtering, extracting, and using medical data contained within a comprehensive electronic medical record. The results of this simulated clinical experiment suggest that the configuration of the intensive care unit user interface contributes significantly to the task load, time to task completion, and number of errors of cognition associated with the identification, and subsequent use, of relevant patient data. Task-specific user interfaces, developed from an understanding of provider information requirements, offer advantages over interfaces currently available within a standard electronic medical record.

Trait susceptibility to worry modulates the effects of cognitive load on cognitive control: An ERP study.

PubMed

Owens, Max; Derakshan, Nazanin; Richards, Anne

2015-10-01

According to the predictions of attentional control theory (ACT) of anxiety (Eysenck, Derakshan, Santos, & Calvo, 2007), worry is a central feature of anxiety that interferes with the ability to inhibit distracting information necessary for successful task performance. However, it is unclear how such cognitive control deficits are modulated by task demands and by the emotionality of the distractors. A sample of 31 participants (25 female) completed a novel flanker task with emotional and neutral distractors under low- and high-cognitive-load conditions. The negative-going N2 event-related potential was measured to index participants' level of top-down resource allocation in the inhibition of distractors under high- and low-load conditions. Results showed N2 amplitudes were larger under high- compared with low-load conditions. In addition, under high but not low load, trait worry was associated with greater N2 amplitudes. Our findings support ACT predictions that trait worry adversely affects goal-directed behavior, and is associated with greater recruitment of cognitive resources to inhibit the impact of distracting information under conditions in which cognitive resources are taxed. (c) 2015 APA, all rights reserved).

Pupillary dilation as an index of task demands.

PubMed

Cabestrero, Raúl; Crespo, Antonio; Quirós, Pilar

2009-12-01

To analyze how pupillary responses reflect mental effort and allocation of processing resources under several load conditions, the pupil diameter of 18 participants was recorded during an auditory digit-span recall task under three load conditions: Low (5 digits), Moderate (8 digits), and Overload (11 digits). In previous research, under all load conditions a significant linear enlargement in pupil diameter was observed as each digit was presented. Significant dilations from the end of the presentation phase to the beginning of the recall phase were also observed but only under low and moderate loads. Contrary to previous research, under the Overload condition, no reduction in pupil diameter was observed when resource limits were exceeded; however, a plateau was observed when the ninth digit was presented until the beginning of the recall phase. Overall, pupillometric data seem to indicate that participants may keep processing actively even though resources are exceeded.

Comparison of different sets of instruments for laparoendoscopic single-site surgery in a surgical simulator with novices.

PubMed

Wang, Dong; Shi, Long-Qing; Wang, Jing-Min; Jiang, Xiao-Hua; Ji, Zhen-Ling

2016-04-01

Given the parallel entry of working instruments through a single incision in laparoendoscopic single-site surgery, loss of triangulation in the abdominal cavity and counteracting movements of the instruments are inevitable obstacles. Some specially designed devices have emerged to ameliorate these challenges. Twenty-four novice participants were randomized into four groups using assigned instruments, conventional straight instruments, single-curved instruments, double-curved instruments and articulating instruments, respectively, to perform two basic tasks (peg transferring and pattern cutting) 14 times in a modified simulator. A test of the tasks and a resection of the intestine segment of a rat were performed. The task scores and evaluation of intraoperative skills during the resection of the intestine segment were recorded. The instrument of modified National Aeronautics and Space Administration Task Load Index (NASA-TLX) was completed. The task scores of the groups using single-curved instruments and articulating instruments were better than the other two groups on the simulator tasks, consistent with the evaluation of intraoperative skills during the resection of intestine segment. As the proficiency with the instruments increased, the task scores improved, as demonstrated by the learning curve. The workload measured by the modified NASA-TLX tool demonstrated that the groups using articulating instruments and double-curved instruments had a heavier workload in most of the categories compared with the other two groups. Single-curved and articulating instruments are more effective than conventional straight and double-curved devices, and are favourable in laparoendoscopic single-site surgery for novice learners. © 2013 Royal Australasian College of Surgeons.

A novel strategy for load balancing of distributed medical applications.

PubMed

Logeswaran, Rajasvaran; Chen, Li-Choo

2012-04-01

Current trends in medicine, specifically in the electronic handling of medical applications, ranging from digital imaging, paperless hospital administration and electronic medical records, telemedicine, to computer-aided diagnosis, creates a burden on the network. Distributed Service Architectures, such as Intelligent Network (IN), Telecommunication Information Networking Architecture (TINA) and Open Service Access (OSA), are able to meet this new challenge. Distribution enables computational tasks to be spread among multiple processors; hence, performance is an important issue. This paper proposes a novel approach in load balancing, the Random Sender Initiated Algorithm, for distribution of tasks among several nodes sharing the same computational object (CO) instances in Distributed Service Architectures. Simulations illustrate that the proposed algorithm produces better network performance than the benchmark load balancing algorithms-the Random Node Selection Algorithm and the Shortest Queue Algorithm, especially under medium and heavily loaded conditions.

Optimization of OSPF Routing in IP Networks

NASA Astrophysics Data System (ADS)

Bley, Andreas; Fortz, Bernard; Gourdin, Eric; Holmberg, Kaj; Klopfenstein, Olivier; Pióro, Michał; Tomaszewski, Artur; Ümit, Hakan

The Internet is a huge world-wide packet switching network comprised of more than 13,000 distinct subnetworks, referred to as Autonomous Systems (ASs) autonomous system AS . They all rely on the Internet Protocol (IP) internet protocol IP for transport of packets across the network. And most of them use shortest path routing protocols shortest path routing!protocols , such as OSPF or IS-IS, to control the routing of IP packets routing!of IP packets within an AS. The idea of the routing is extremely simple — every packet is forwarded on IP links along the shortest route between its source and destination nodes of the AS. The AS network administrator can manage the routing of packets in the AS by supplying the so-called administrative weights of IP links, which specify the link lengths that are used by the routing protocols for their shortest path computations. The main advantage of the shortest path routing policy is its simplicity, allowing for little administrative overhead. From the network engineering perspective, however, shortest path routing can pose problems in achieving satisfactory traffic handling efficiency. As all routing paths depend on the same routing metric routing!metric , it is not possible to configure the routing paths for the communication demands between different pairs of nodes explicitly or individually; the routing can be controlled only indirectly and only as a whole by modifying the routing metric. Thus, one of the main tasks when planning such networks is to find administrative link weights that induce a globally efficient traffic routing traffic!routing configuration of an AS. It turns out that this task leads to very difficult mathematical optimization problems. In this chapter, we discuss and describe exact integer programming models and solution approaches as well as practically efficient smart heuristics for such shortest path routing problems shortest path routing!problems .

The Frequency of Rapid Pupil Dilations as a Measure of Linguistic Processing Difficulty

PubMed Central

Demberg, Vera; Sayeed, Asad

2016-01-01

While it has long been known that the pupil reacts to cognitive load, pupil size has received little attention in cognitive research because of its long latency and the difficulty of separating effects of cognitive load from the light reflex or effects due to eye movements. A novel measure, the Index of Cognitive Activity (ICA), relates cognitive effort to the frequency of small rapid dilations of the pupil. We report here on a total of seven experiments which test whether the ICA reliably indexes linguistically induced cognitive load: three experiments in reading (a manipulation of grammatical gender match / mismatch, an experiment of semantic fit, and an experiment comparing locally ambiguous subject versus object relative clauses, all in German), three dual-task experiments with simultaneous driving and spoken language comprehension (using the same manipulations as in the single-task reading experiments), and a visual world experiment comparing the processing of causal versus concessive discourse markers. These experiments are the first to investigate the effect and time course of the ICA in language processing. All of our experiments support the idea that the ICA indexes linguistic processing difficulty. The effects of our linguistic manipulations on the ICA are consistent for reading and auditory presentation. Furthermore, our experiments show that the ICA allows for usage within a multi-task paradigm. Its robustness with respect to eye movements means that it is a valid measure of processing difficulty for usage within the visual world paradigm, which will allow researchers to assess both visual attention and processing difficulty at the same time, using an eye-tracker. We argue that the ICA is indicative of activity in the locus caeruleus area of the brain stem, which has recently also been linked to P600 effects observed in psycholinguistic EEG experiments. PMID:26799065

Comparing the Workload Perceptions of Identifying Patient Condition and Priorities of Care Among Burn Providers in Three Burn ICUs.

PubMed

McInnis, Ian; Murray, Sarah J; Serio-Melvin, Maria; Aden, James K; Mann-Salinas, Elizabeth; Chung, Kevin K; Huzar, Todd; Wolf, Steven; Nemeth, Christopher; Pamplin, Jeremy C

Multidisciplinary rounds (MDRs) in the burn intensive care unit serve as an efficient means for clinicians to assess patient status and establish patient care priorities. Both tasks require significant cognitive work, the magnitude of which is relevant because increased cognitive work of task completion has been associated with increased error rates. We sought to quantify this workload during MDR using the National Aeronautics and Space Administration Task Load Index (NASA-TLX). Research staff at three academic regional referral burn centers administered the NASA-TLX to clinicians during MDR. Clinicians assessed their workload associated with 1) "Identify(ing) if the patient is better, same, or worse than yesterday" and 2) "Identify(ing) the most important objectives of care for the patient today." Data were collected on clinician type, years of experience, and hours of direct patient care. Surveys were administered to 116 total clinicians, 41 physicians, 25 nurses, 13 medical students, and 37 clinicians in other roles. Clinicians with less experience reported more cognitive work when completing both tasks (P < .005). Clinicians in the "others" group (respiratory therapists, dieticians, pharmacists, etc.) reported less cognitive work than all other groups for both tasks (P < .05). The NASA-TLX was an effective tool for collecting perceptions of cognitive workload associated with MDR. Perceived cognitive work varied by clinician type and experience level when completing two key tasks. Less experience was associated with increased perceived work, potentially increasing mental error rates, and increasing risk to patients. Creating tools or work processes to reduce cognitive work may improve clinician performance.

Baseline and Multimodal UAV GCS Interface Design

DTIC Science & Technology

2013-07-01

complete a computerized version of the NASA - TLX assessment of perceived mental workload. 2.3 Results The baseline condition ran smoothly and with...System MALE Medium-altitude, Long-endurance NASA - TLX NASA Task Load Index SA Situation Awareness TDT Tucker Davis Technologies UAV Uninhabited Aerial

Health Literacy and Task Environment Influence Parents' Burden for Data Entry on Child-Specific Health Information: Randomized Controlled Trial

PubMed Central

Guo, Chao-Yu; Bacic, Janine; Chan, Eugenia

2011-01-01

Background Health care systems increasingly rely on patients’ data entry efforts to organize and assist in care delivery through health information exchange. Objectives We sought to determine (1) the variation in burden imposed on parents by data entry efforts across paper-based and computer-based environments, and (2) the impact, if any, of parents’ health literacy on the task burden. Methods We completed a randomized controlled trial of parent-completed data entry tasks. Parents of children with attention deficit hyperactivity disorder (ADHD) were randomized based on the Test of Functional Health Literacy in Adults (TOFHLA) to either a paper-based or computer-based environment for entry of health information on their children. The primary outcome was the National Aeronautics and Space Administration Task Load Index (TLX) total weighted score. Results We screened 271 parents: 194 (71.6%) were eligible, and 180 of these (92.8%) constituted the study cohort. We analyzed 90 participants from each arm. Parents who completed information tasks on paper reported a higher task burden than those who worked in the computer environment: mean (SD) TLX scores were 22.8 (20.6) for paper and 16.3 (16.1) for computer. Assignment to the paper environment conferred a significant risk of higher task burden (F1,178 = 4.05, P = .046). Adequate literacy was associated with lower task burden (decrease in burden score of 1.15 SD, P = .003). After adjusting for relevant child and parent factors, parents’ TOFHLA score (beta = -.02, P = .02) and task environment (beta = .31, P = .03) remained significantly associated with task burden. Conclusions A tailored computer-based environment provided an improved task experience for data entry compared to the same tasks completed on paper. Health literacy was inversely related to task burden. Trial registration Clinicaltrials.gov NCT00543257; http://www.clinicaltrials.gov/ct2/show/NCT00543257 (Archived by WebCite at http://www.webcitation.org/5vUVH2DYR) PMID:21269990

Load Carriage: An Integrated Risk Management Approach.

PubMed

Orr, Robin M; Pope, Rodney R

2015-11-01

Military load carriage (LC) gives rise to substantial risks to soldier health, tactical performance, and mission success. The aim of this article was to extract and synthesize the key findings of a series of LC research reports previously published by the authors. Five reviews and 6 studies were included, with key findings extracted and synthesized in tabulated and critical narrative form. The weight of a soldier's load is a source of risk for soldier's injuries and tactical task performance. The resulting level of risk is influenced by risk modifiers (like speed of march, terrain grade, and task type and duration) and risk controls (like administrative controls and physical conditioning). In the Australian context, these risk controls were limited, with soldiers carrying heavier loads than those mandated by doctrine and policy, and LC conditioning not meeting best practice. The diversity of LC contexts, combined with the influence of risk modifiers and risk controls, means that levels of risk associated with LC are not consistent and must be assessed on a case-by-case basis. Load weight and marching routes (terrains, gradients), distances, speed, and duration are all potentially treatable sources of LC-related risk. Potential risk treatments include not only commanders directly addressing these specific sources of risk to the extent feasible, on a case-by-case basis, when planning or conducting LC tasks but also improving administration controls (i.e., doctrine and policies) and personal protection (i.e., the physical conditioning of the soldier) as part of the hierarchy of controls. Practical application would involve commanders developing and implementing dedicated LC doctrine and policies and implementing and enforcing LC conditioning programs that meets best practice.

Use of EEG workload indices for diagnostic monitoring of vigilance decrement.

PubMed

Kamzanova, Altyngul T; Kustubayeva, Almira M; Matthews, Gerald

2014-09-01

A study was run to test which of five electroencephalographic (EEG) indices was most diagnostic of loss of vigilance at two levels of workload. EEG indices of alertness include conventional spectral power measures as well as indices combining measures from multiple frequency bands, such as the Task Load Index (TLI) and the Engagement Index (El). However, it is unclear which indices are optimal for early detection of loss of vigilance. Ninety-two participants were assigned to one of two experimental conditions, cued (lower workload) and uncued (higher workload), and then performed a 40-min visual vigilance task. Performance on this task is believed to be limited by attentional resource availability. EEG was recorded continuously. Performance, subjective state, and workload were also assessed. The task showed a vigilance decrement in performance; cuing improved performance and reduced subjective workload. Lower-frequency alpha (8 to 10.9 Hz) and TLI were most sensitive to the task parameters. The magnitude of temporal change was larger for lower-frequency alpha. Surprisingly, higher TLI was associated with superior performance. Frontal theta and El were influenced by task workload only in the final period of work. Correlational data also suggested that the indices are distinct from one another. Lower-frequency alpha appears to be the optimal index for monitoring vigilance on the task used here, but further work is needed to test how diagnosticity of EEG indices varies with task demands. Lower-frequency alpha may be used to diagnose loss of operator alertness on tasks requiring vigilance.

Training improves laparoscopic tasks performance and decreases operator workload.

PubMed

Hu, Jesse S L; Lu, Jirong; Tan, Wee Boon; Lomanto, Davide

2016-05-01

It has been postulated that increased operator workload during task performance may increase fatigue and surgical errors. The National Aeronautics and Space Administration-Task Load Index (NASA-TLX) is a validated tool for self-assessment for workload. Our study aims to assess the relationship of workload and performance of novices in simulated laparoscopic tasks of different complexity levels before and after training. Forty-seven novices without prior laparoscopic experience were recruited in a trial to investigate whether training improves task performance as well as mental workload. The participants were tested on three standard tasks (ring transfer, precision cutting and intracorporeal suturing) in increasing complexity based on the Fundamentals of Laparoscopic Surgery (FLS) curriculum. Following a period of training and rest, participants were tested again. Test scores were computed from time taken and time penalties for precision errors. Test scores and NASA-TLX scores were recorded pre- and post-training and analysed using paired t tests. One-way repeated measures ANOVA was used to analyse differences in NASA-TLX scores between the three tasks. NASA-TLX score was lowest with ring transfer and highest with intracorporeal suturing. This was statistically significant in both pre-training (p < 0.001) and post-training (p < 0.001). NASA-TLX scores mirror the changes in test scores for the three tasks. Workload scores decreased significantly after training for all three tasks (ring transfer = 2.93, p < 0.001, precision cutting = 3.74, p < 0.001, intracorporeal suturing = 2.98, p < 0.001). NASA-TLX score is an accurate reflection of the complexity of simulated laparoscopic tasks in the FLS curriculum. This also correlates with the relationship of test scores between the three tasks. Simulation training improves both performance score and workload score across the tasks.

Lateralized effects of orthographical irregularity and auditory memory load on the kinematics of transcription typewriting.

PubMed

Bloemsaat, Gijs; Van Galen, Gerard P; Meulenbroek, Ruud G J

2003-05-01

This study investigated the combined effects of orthographical irregularity and auditory memory load on the kinematics of finger movements in a transcription-typewriting task. Eight right-handed touch-typists were asked to type 80 strings of ten seven-letter words. In half the trials an irregularly spelt target word elicited a specific key press sequence of either the left or right index finger. In the other trials regularly spelt target words elicited the same key press sequence. An auditory memory load was added in half the trials by asking participants to remember the pitch of a tone during task performance. Orthographical irregularity was expected to slow down performance. Auditory memory load, viewed as a low level stressor, was expected to affect performance only when orthographically irregular words needed to be typed. The hypotheses were confirmed. Additional analysis showed differential effects on the left and right hand, possibly related to verbal-manual interference and hand dominance. The results are discussed in relation to relevant findings of recent neuroimaging studies.

Predicting dual-task performance with the Multiple Resources Questionnaire (MRQ).

PubMed

Boles, David B; Bursk, Jonathan H; Phillips, Jeffrey B; Perdelwitz, Jason R

2007-02-01

The objective was to assess the validity of the Multiple Resources Questionnaire (MRQ) in predicting dual-task interference. Subjective workload measures such as the Subjective Workload Assessment Technique (SWAT) and NASA Task Load Index are sensitive to single-task parameters and dual-task loads but have not attempted to measure workload in particular mental processes. An alternative is the MRQ. In Experiment 1, participants completed simple laboratory tasks and the MRQ after each. Interference between tasks was then correlated to three different task similarity metrics: profile similarity, based on r(2) between ratings; overlap similarity, based on summed minima; and overall demand, based on summed ratings. Experiment 2 used similar methods but more complex computer-based games. In Experiment 1 the MRQ moderately predicted interference (r = +.37), with no significant difference between metrics. In Experiment 2 the metric effect was significant, with overlap similarity excelling in predicting interference (r = +.83). Mean ratings showed high diagnosticity in identifying specific mental processing bottlenecks. The MRQ shows considerable promise as a cognitive-process-sensitive workload measure. Potential applications of the MRQ include the identification of dual-processing bottlenecks as well as process overloads in single tasks, preparatory to redesign in areas such as air traffic management, advanced flight displays, and medical imaging.

Higher mental workload is associated with poorer laparoscopic performance as measured by the NASA-TLX tool.

PubMed

Yurko, Yuliya Y; Scerbo, Mark W; Prabhu, Ajita S; Acker, Christina E; Stefanidis, Dimitrios

2010-10-01

Increased workload during task performance may increase fatigue and facilitate errors. The National Aeronautics and Space Administration-Task Load Index (NASA-TLX) is a previously validated tool for workload self-assessment. We assessed the relationship of workload and performance during simulator training on a complex laparoscopic task. NASA-TLX workload data from three separate trials were analyzed. All participants were novices (n = 28), followed the same curriculum on the fundamentals of laparoscopic surgery suturing model, and were tested in the animal operating room (OR) on a Nissen fundoplication model after training. Performance and workload scores were recorded at baseline, after proficiency achievement, and during the test. Performance, NASA-TLX scores, and inadvertent injuries during the test were analyzed and compared. Workload scores declined during training and mirrored performance changes. NASA-TLX scores correlated significantly with performance scores (r = -0.5, P < 0.001). Participants with higher workload scores caused more inadvertent injuries to adjacent structures in the OR (r = 0.38, P < 0.05). Increased mental and physical workload scores at baseline correlated with higher workload scores in the OR (r = 0.52-0.82; P < 0.05) and more inadvertent injuries (r = 0.52, P < 0.01). Increased workload is associated with inferior task performance and higher likelihood of errors. The NASA-TLX questionnaire accurately reflects workload changes during simulator training and may identify individuals more likely to experience high workload and more prone to errors during skill transfer to the clinical environment.

The effect of augmented real-time image guidance on task workload during endoscopic sinus surgery.

PubMed

Dixon, Benjamin J; Chan, Harley; Daly, Michael J; Vescan, Allan D; Witterick, Ian J; Irish, Jonathan C

2012-01-01

Due to proximity to critical structures, the need for spatial awareness during endoscopic sinus surgery (ESS) is essential. We have developed an augmented, real-time image-guided surgery (ART-IGS) system that provides live navigational data and proximity alerts to the operating surgeon during ablation. We wished to test the hypothesis that task workload would be reduced when using this technology. A trial involved 8 otolaryngology residents and fellows performing ESS on cadaveric specimens; 1 side in a conventional method (control) and 1 side with ART-IGS. After computed tomography scanning, anatomical contouring, and registration of the head, a three-dimensional (3D) virtual endoscopic view, ablative tool tracking, and proximity alerts were enabled. Each subject completed ESS tasks and rated their workload during and after the exercise using the National Aeronautics and Space Administration (NASA) Task Load Index (TLX). A questionnaire and open feedback interview were completed after the procedure. There was a significant reduction in mental demand, temporal demand, effort, and frustration when using the ART-IGS system in comparison to the control (p < 0.02). Perceived performance was increased (p = 0.02). Most subjects agreed that the system was sufficiently accurate, caused minimal interruption, and increased confidence. Optical tracking line-of-sight issues were frequently cited as the main limitation early in the study; however, this was largely resolved. ART-IGS reduces task workload for trainees performing ESS. Live navigation and alert zones may be a valuable intraoperative teaching aid. Copyright © 2012 American Rhinologic Society-American Academy of Otolaryngic Allergy, LLC.

Reduced mental capacity and behavior of a rider of a bicycle simulator under alcohol stress or under dual task load

NASA Technical Reports Server (NTRS)

Soede, M.

1977-01-01

Experiments were carried out on a bicycle simulator with alcohol administration and a binary choice task in separate sessions, intending to reduce the subject's mental capacity. Before and after such sessions a visual evoked response measurement was done. The subject's performance was analyzed with describing function techniques. The results indicate that the alcohol affects the course-following task as well as the balancing task. The binary choice task is more specifically influencing the course-following task. The dual task shows a more pronounced effect on the recovery of the evoked response. The alcohol is delaying the recovery curve of the evoked response. A tentative explanation can be given which agrees with the performance data.

Effects of static fingertip loading on carpal tunnel pressure

NASA Technical Reports Server (NTRS)

Rempel, D.; Keir, P. J.; Smutz, W. P.; Hargens, A.

1997-01-01

The purpose of this study was to explore the relationship between carpal tunnel pressure and fingertip force during a simple pressing task. Carpal tunnel pressure was measured in 15 healthy volunteers by means of a saline-filled catheter inserted percutaneously into the carpal tunnel of the nondominant hand. The subjects pressed on a load cell with the tip of the index finger and with 0, 6, 9, and 12 N of force. The task was repeated in 10 wrist postures: neutral; 10 and 20 degrees of ulnar deviation; 10 degrees of radial deviation; and 15, 30, and 45 degrees of both flexion and extension. Fingertip loading significantly increased carpal tunnel pressure for all wrist angles (p = 0.0001). Post hoc analyses identified significant increase (p < 0.05) in carpal tunnel pressure between unloaded (0 N) and all loaded conditions, as well as between the 6 and 12 N load conditions. This study demonstrates that the process whereby fingertip loading elevates carpal tunnel pressure is independent of wrist posture and that relatively small fingertip loads have a large effect on carpal tunnel pressure. It also reveals the response characteristics of carpal tunnel pressure to fingertip loading, which is one step in understanding the relationship between sustained grip and pinch activities and the aggravation or development of median neuropathy at the wrist.

Developing Best Practices for Capturing As-Built Building Information Models (BIM) for Existing Facilities

DTIC Science & Technology

2010-08-01

students conducting the data capture and data entry, an analytical method known as the Task Load Index ( NASA TLX Version 2.0) was used. This method was...published by the NASA Ames Research Center in December 2003. The entire report can be found at: http://humansystems.arc.nasa.gov/groups/ TLX The...completion of each task in the survey process, surveyors were required to complete a NASA TLX form to report their assessment of the workload for

Perceptual load manipulation reveals sensitivity of the face-selective N170 to attention.

PubMed

Mohamed, Tarik N; Neumann, Markus F; Schweinberger, Stefan R

2009-05-27

It has been controversial whether the face-sensitive N170 is affected by selective attention. We manipulated attention sensu Lavie's perceptual load theory to short (200 ms) presentations of task-irrelevant unfamiliar faces or houses, while participants identified superimposed target letters 'X' versus 'N'. These targets were strings of either six identical (low load) or six different letters (high load). Under low load, we found a prominent face-selective N170 response. Under high load, however, we not only observed a dramatic reduction of the face N170 but also an unexpected enhancement of the house N170, such that face selectivity was almost completely lost. We conclude that the early stages of face processing indexed by the N170 strongly depend on selective attention.

Is it important to know the load mass in lifting tasks to prevent falls?

PubMed

Azevedo, Rui; Mourão, Paulo; Abade, Eduardo; Carvalho, Alberto

2015-01-01

Lifting objects without knowing its weight may result in postural imbalances and be a risk factor for falls. The aim of this study was to examine the influence of the load knowledge in postural balance when lifting different weight loads. Thirteen male subjects (23.8 ± 3.1 years; 73.5 ± 7.8 kg; 179.1 ± 7.5 cm; foot length, 25.7 ± 1.2 cm) participated in the study. The effect of the weight overestimation on the postural stability was measured by the Index of Proximity to Stability Boundary (IPSB) and through the anterior-posterior and medio-lateral lengths displacements of the Center of Pressure (CoP). The results showed an increase in the IPSB when the 5 kg lifting task was performed with load knowledge. Moreover, the length of the antero-posterior and medio-lateral CoP displacement was reduced in the 5 kg lift with knowledge. Results showed that the lack of the loads' knowledge may lead to balance loss. Thus, when the preparation processes are not adequate, picking up similar objects with different loads may increase the risk of fall, mainly when a light weight is suddenly lifted up after a heavy one.

Air traffic control specialist visual scanning II : task load, visual noise, and intrusions into controlled airspace.

DOT National Transportation Integrated Search

1999-12-01

The Federal Aviation Administration (FAA) started an Air Traffic Control Specialist (ATCS) information-scanning program a number : of years ago. The goal is to learn about how controllers use information displays and develop techniques for reducing a...

The incorporation of focused history in checklist for early recognition and treatment of acute illness and injury.

PubMed

Jayaprakash, Namita; Ali, Rashid; Kashyap, Rahul; Bennett, Courtney; Kogan, Alexander; Gajic, Ognjen

2016-08-31

Diagnostic error and delay are critical impediments to the safety of critically ill patients. Checklist for early recognition and treatment of acute illness and injury (CERTAIN) has been developed as a tool that facilitates timely and error-free evaluation of critically ill patients. While the focused history is an essential part of the CERTAIN framework, it is not clear how best to choreograph this step in the process of evaluation and treatment of the acutely decompensating patient. An un-blinded crossover clinical simulation study was designed in which volunteer critical care clinicians (fellows and attendings) were randomly assigned to start with either obtaining a focused history choreographed in series (after) or in parallel to the primary survey. A focused history was obtained using the standardized SAMPLE model that is incorporated into American College of Trauma Life Support (ATLS) and Pediatric Advanced Life Support (PALS). Clinicians were asked to assess six acutely decompensating patients using pre - determined clinical scenarios (three in series choreography, three in parallel). Once the initial choreography was completed the clinician would crossover to the alternative choreography. The primary outcome was the cognitive burden assessed through the NASA task load index. Secondary outcome was time to completion of a focused history. A total of 84 simulated cases (42 in parallel, 42 in series) were tested on 14 clinicians. Both the overall cognitive load and time to completion improved with each successive practice scenario, however no difference was observed between the series versus parallel choreographies. The median (IQR) overall NASA TLX task load index for series was 39 (17 - 58) and for parallel 43 (27 - 52), p = 0.57. The median (IQR) time to completion of the tasks in series was 125 (112 - 158) seconds and in parallel 122 (108 - 158) seconds, p = 0.92. In this clinical simulation study assessing the incorporation of a focused history into the primary survey of a non-trauma critically ill patient, there was no difference in cognitive burden or time to task completion when using series choreography (after the exam) compared to parallel choreography (concurrent with the primary survey physical exam). However, with repetition of the task both overall task load and time to completion improved in each of the choreographies.

A Study on the Validity of a Task Complexity Measure for Emergency Operating Procedures of Nuclear Power Plants—Comparing With a Subjective Workload

NASA Astrophysics Data System (ADS)

Park, J.; Jung, W.

2006-10-01

In this study, the appropriateness of the task complexity (TACOM) measure that can quantify the complexity of emergency tasks was investigated by comparing subjective workload scores with the associated TACOM scores. To this end, based on the NASA-TLX (task load index) technique, 18 operators were asked to subjectively estimate perceived workload for 23 emergency tasks that were specified in the emergency operating procedures of the reference nuclear power plants. As the result of comparisons, it was observed that subjective workload scores increase in proportion to the increase of TACOM scores. Therefore, it is expect that the TACOM measure can be used as a serviceable method to quantify the complexity of emergency tasks

Ergonomic assessment of airport shuttle driver tasks using an ergonomic analysis toolset.

PubMed

Çakıt, Erman

2018-06-01

This study aimed to (a) evaluate strength requirements and lower back stresses during lifting and baggage handling tasks with the 3D Static Strength Prediction Program (3DSSPP) and (b) provide additional analyses using rapid entire body assessment (REBA) and the NASA task load index (TLX) to assess the risks associated with the tasks. Four healthy female shuttle drivers of good health aged between 55 and 60 years were observed and interviewed in an effort to determine the tasks required of their occupations. The results indicated that lifting bags and placing them in a shuttle were high risk for injury and possible changes should be further investigated. The study concluded there was a potential for injury associated with baggage storing and retrieval tasks of a shuttle driver.

Variation in work tasks in relation to pinch grip strength among middle-aged female dentists.

PubMed

Ding, Hebo; Leino-Arjas, Päivi; Murtomaa, Heikki; Takala, Esa-Pekka; Solovieva, Svetlana

2013-11-01

We aimed to investigate the relationship of task variation during dental work history with pinch grip strength among dentists. We measured pinch grip strength among 295 female Finnish dentists aged 45-63 years. Variation in dental work tasks during work history was empirically defined by cluster analysis. Three clusters of task variation emerged: low (most work time in restoration treatment/endodontics), moderate (about 50% in the former and 50% in prosthodontics/periodontics/surgery), and high (variable tasks including administrative duties). Hand radiographs were examined for the presence of OA in the wrist and each joint of the 1-3rd fingers. Information on hand-loading leisure-time activities, and joint pain was obtained by questionnaire. Glove size was used as a proxy for hand size. BMI (kg/m2) was based on measured weight and self-reported height. Dentists with low variation of work task history had an increased risk of low pinch grip strength in the right hand (OR 2.3, 95% CI 1.2-4.3), but not in the left (1.13, 0.62-2.08), compared to dentists with high task variation, independent of age, hand size, hand-loading leisure-time activities, BMI and symptomatic hand OA. The dentists with the most hand-loading tasks were at an increased risk of low pinch grip strength, independent of e.g. symptomatic hand OA. It is advisable among dentists to perform as diverse work tasks as possible to reduce the risk of decreased pinch grip strength. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Auditory working memory impairments in individuals at familial high risk for schizophrenia.

PubMed

Seidman, Larry J; Meyer, Eric C; Giuliano, Anthony J; Breiter, Hans C; Goldstein, Jill M; Kremen, William S; Thermenos, Heidi W; Toomey, Rosemary; Stone, William S; Tsuang, Ming T; Faraone, Stephen V

2012-05-01

The search for predictors of schizophrenia has accelerated with a growing focus on early intervention and prevention of psychotic illness. Studying nonpsychotic relatives of individuals with schizophrenia enables identification of markers of vulnerability for the illness independent of confounds associated with psychosis. The goal of these studies was to develop new auditory continuous performance tests (ACPTs) and evaluate their effects in individuals with schizophrenia and their relatives. We carried out two studies of auditory vigilance with tasks involving working memory (WM) and interference control with increasing levels of cognitive load to discern the information-processing vulnerabilities in a sample of schizophrenia patients, and two samples of nonpsychotic relatives of individuals with schizophrenia and controls. Study 1 assessed adults (mean age = 41), and Study 2 assessed teenagers and young adults age 13-25 (M = 19). Patients with schizophrenia were impaired on all five versions of the ACPTs, whereas relatives were impaired only on WM tasks, particularly the two interference tasks that maximize cognitive load. Across all groups, the interference tasks were more difficult to perform than the other tasks. Schizophrenia patients performed worse than relatives, who performed worse than controls. For patients, the effect sizes were large (Cohen's d = 1.5), whereas for relatives they were moderate (d = ~0.40-0.50). There was no age by group interaction in the relatives-control comparison except for participants <31 years of age. Novel WM tasks that manipulate cognitive load and interference control index an important component of the vulnerability to schizophrenia.

Nanovesicles for transdermal delivery of felodipine: Development, characterization, and pharmacokinetics

PubMed Central

Yusuf, Mohd; Sharma, Vijay; Pathak, Kamla

2014-01-01

Aim: The research traces development of nanovesicles to attain enhanced transdermal delivery of felodipine and also investigates parameters for optimization of variable membrane compositions containing soya- and egg lecithin and edge activator. Materials and Methods: Rotary evaporation sonication method was employed to obtain tranfersomal formulation that was characterized for vesicle shape and size, polydispersity index (PDI), zeta potential, entrapment and loading efficiency, deformability index and in vitro skin permeation. Results: Spherical nanovesicles of 75.71 ± 5.4 nm with PDI 0.228 and zeta potential of −49.8 were adjudged as the best formulation (MF8). MF8 displayed maximum entrapment and loading efficiency with a high deformability index of 119.68. In vitro permeation across rat skin by MF8 reported 256% enhancement in permeation (flux = 23.72 ± 0.64) when compared with transdermal control formulation and followed zero order kinetics (Case-II). Pharmacokinetic studies revealed that transdermal administration, in contrast to oral delivery provided relatively constant, sustained blood concentration with minimal plasma fluctuation, rapid and prolonged peak time. The relative bioavailability of felodipine was found 358.42% versus oral administration that was well supported by the outcomes of confocal laser scanning microscopic studies that suggested rapid permeation of drugs to across dermal layers. Conclusion: The results conclude that composition variation and method of preparation elicited significant effect on the vesicle characteristic and proved the transcendency of felodipine loaded transfersomes. PMID:25126525

Anticipation, teamwork and cognitive load: chasing efficiency during robot-assisted surgery.

PubMed

Sexton, Kevin; Johnson, Amanda; Gotsch, Amanda; Hussein, Ahmed A; Cavuoto, Lora; Guru, Khurshid A

2018-02-01

Robot-assisted surgery (RAS) has changed the traditional operating room (OR), occupying more space with equipment and isolating console surgeons away from the patients and their team. We aimed to evaluate how anticipation of surgical steps and familiarity between team members impacted efficiency. We analysed recordings (video and audio) of 12 robot-assisted radical prostatectomies. Any requests between surgeon and the team members were documented and classified by personnel, equipment type, mode of communication, level of inconvenience in fulfilling the request and anticipation. Surgical team members completed questionnaires assessing team familiarity and cognitive load (National Aeronautics and Space Administration - Task Load Index). Predictors of team efficiency were assessed using Pearson correlation and stepwise linear regression. 1330 requests were documented, of which 413 (31%) were anticipated. Anticipation correlated negatively with operative time, resulting in overall 8% reduction of OR time. Team familiarity negatively correlated with inconveniences. Anticipation ratio, per cent of requests that were non-verbal and total request duration were significantly correlated with the console surgeons' cognitive load (r=0.77, p=0.006; r=0.63, p=0.04; and r=0.70, p=0.02, respectively). Anticipation and active engagement by the surgical team resulted in shorter operative time, and higher familiarity scores were associated with fewer inconveniences. Less anticipation and non-verbal requests were also associated with lower cognitive load for the console surgeon. Training efforts to increase anticipation and team familiarity can improve team efficiency during RAS. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Quantifying the impact of cross coverage on physician's workload and performance in radiation oncology.

PubMed

Mosaly, Prithima R; Mazur, Lukasz M; Jones, Ellen L; Hoyle, Lesley; Zagar, Timothy; Chera, Bhishamjit S; Marks, Lawrence B

2013-01-01

To quantitatively assess the difference in workload and performance of radiation oncology physicians during radiation therapy treatment planning tasks under the conditions of "cross coverage" versus planning a patient with whom they were familiar. Eight physicians (3 experienced faculty physicians and 5 physician residents) performed 2 cases. The first case represented a "cross-coverage" scenario where the physicians had no prior information about the case to be planned. The second exposure represented a "regular-coverage" scenario where the physicians were familiar with the patient case to be planned. Each case involved 3 tasks to be completed systematically. Workload was assessed both subjectively (perceived) using National Aeronautics and Space Administration-Task Load Index (NASA-TLX), and objectively (physiological) throughout the task using eye data (via monitoring pupil size and blink rate). Performance of each task and the case was measured using completion time. Subjective willingness to approve or disapprove the generated plan was obtained after completion of the case only. Forty-eight perceived and 48 physiological workload assessments were obtained. Overall, results revealed a significant increase in perceived workload (high NASA-TLX score) and decrease in performance (longer completion time and reduced approval rate) during cross coverage. There were nonsignificant increases in pupil diameter and decreases in the blink rate during cross-coverage versus regular-coverage scenario. In both cross-coverage and regular-coverage scenarios the level of experience did not affect workload and performance. The cross-coverage scenario significantly increases perceived workload and degrades performance versus regular coverage. Hence, to improve patient safety, efforts must be made to develop policies, standard operating procedures, and usability improvements to electronic medical record and treatment planning systems for "easier" information processing to deal with cross coverage, while recognizing strengths and limitations of human performance. Published by Elsevier Inc.

Factors contributing to nursing task incompletion as perceived by nurses working in Kuwait general hospitals.

PubMed

Al-Kandari, Fatimah; Thomas, Deepa

2009-12-01

Unfinished care has a strong relationship with quality of nursing care. Most issues related to tasks incompletion arise from staffing and workload. This study was conducted to assess the workload of nurses, the nursing activities (tasks) nurses commonly performed on medical and surgical wards, elements of nursing care activities left incomplete by nurses during a shift, factors contributing to task incompletion and the relationship between staffing, demographic variables and task incompletion. Exploratory survey using a self-administered questionnaire developed from IHOC survey, USA. All full time registered nurses working on the general medical and surgical wards of five government general hospitals in Kuwait. Research assistants distributed and collected back the questionnaires. Four working days were given to participants to complete and return the questionnaires. A total of 820 questionnaires were distributed and 95% were returned. Descriptive and inferential analysis using SPSS-11. The five most frequently performed nursing activities were: administration of medications, assessing patient condition, preparing/updating nursing care plans, close patient monitoring and client health teaching. The most common nursing activities nurses were unable to complete were: comfort talk with patient and family, adequate documentation of nursing care, oral hygiene, routine catheter care and starting or changing IV fluid on time. Tasks were more complete when the nurse-patient load was less than 5. Nurses' age and educational background influenced task completion while nurses' gender had no influence on it. Increased patient loads, resulting in increased frequency of nursing tasks and non-nursing tasks, were positively correlated to incompletion of nursing activities during the shift. Emphasis should be given to maintaining the optimum nurse-patient load and decreasing the non-nursing workload of nurses to enhance the quality of nursing care.

Intrinsic resting-state activity predicts working memory brain activation and behavioral performance.

PubMed

Zou, Qihong; Ross, Thomas J; Gu, Hong; Geng, Xiujuan; Zuo, Xi-Nian; Hong, L Elliot; Gao, Jia-Hong; Stein, Elliot A; Zang, Yu-Feng; Yang, Yihong

2013-12-01

Although resting-state brain activity has been demonstrated to correspond with task-evoked brain activation, the relationship between intrinsic and evoked brain activity has not been fully characterized. For example, it is unclear whether intrinsic activity can also predict task-evoked deactivation and whether the rest-task relationship is dependent on task load. In this study, we addressed these issues on 40 healthy control subjects using resting-state and task-driven [N-back working memory (WM) task] functional magnetic resonance imaging data collected in the same session. Using amplitude of low-frequency fluctuation (ALFF) as an index of intrinsic resting-state activity, we found that ALFF in the middle frontal gyrus and inferior/superior parietal lobules was positively correlated with WM task-evoked activation, while ALFF in the medial prefrontal cortex, posterior cingulate cortex, superior frontal gyrus, superior temporal gyrus, and fusiform gyrus was negatively correlated with WM task-evoked deactivation. Further, the relationship between the intrinsic resting-state activity and task-evoked activation in lateral/superior frontal gyri, inferior/superior parietal lobules, superior temporal gyrus, and midline regions was stronger at higher WM task loads. In addition, both resting-state activity and the task-evoked activation in the superior parietal lobule/precuneus were significantly correlated with the WM task behavioral performance, explaining similar portions of intersubject performance variance. Together, these findings suggest that intrinsic resting-state activity facilitates or is permissive of specific brain circuit engagement to perform a cognitive task, and that resting activity can predict subsequent task-evoked brain responses and behavioral performance. Copyright © 2012 Wiley Periodicals, Inc.

The emotional startle effect is disrupted by a concurrent working memory task.

PubMed

King, Rosemary; Schaefer, Alexandre

2011-02-01

Working memory (WM) processes are often thought to play an important role in the cognitive regulation of negative emotions. However, little is known about how they influence emotional processing. We report two experiments that tested whether a concurrent working memory task could modulate the emotional startle eyeblink effect, a well-known index of emotional processing. In both experiments, emotionally negative and neutral pictures were viewed in two conditions: a "cognitive load" (CL) condition, in which participants had to actively maintain information in working memory (WM) while viewing the pictures, and a control "no load" (NL) condition. Picture-viewing instructions were identical across CL and NL. In both experiments, results showed a significant reduction of the emotional modulation of the startle eyeblink reflex in the CL condition compared to the NL condition. These findings suggest that a concurrent WM task disrupts emotional processing even when participants are directing visual focus on emotionally relevant information. Copyright © 2010 Society for Psychophysiological Research.

Spatial Scaling of the Profile of Selective Attention in the Visual Field.

PubMed

Gannon, Matthew A; Knapp, Ashley A; Adams, Thomas G; Long, Stephanie M; Parks, Nathan A

2016-01-01

Neural mechanisms of selective attention must be capable of adapting to variation in the absolute size of an attended stimulus in the ever-changing visual environment. To date, little is known regarding how attentional selection interacts with fluctuations in the spatial expanse of an attended object. Here, we use event-related potentials (ERPs) to investigate the scaling of attentional enhancement and suppression across the visual field. We measured ERPs while participants performed a task at fixation that varied in its attentional demands (attentional load) and visual angle (1.0° or 2.5°). Observers were presented with a stream of task-relevant stimuli while foveal, parafoveal, and peripheral visual locations were probed by irrelevant distractor stimuli. We found two important effects in the N1 component of visual ERPs. First, N1 modulations to task-relevant stimuli indexed attentional selection of stimuli during the load task and further correlated with task performance. Second, with increased task size, attentional modulation of the N1 to distractor stimuli showed a differential pattern that was consistent with a scaling of attentional selection. Together, these results demonstrate that the size of an attended stimulus scales the profile of attentional selection across the visual field and provides insights into the attentional mechanisms associated with such spatial scaling.

Workplace Conditions and the Rise and Fall of Teachers' Commitment.

ERIC Educational Resources Information Center

Rosenholtz, Susan J.; Simpson, Carl

1990-01-01

Examines 1,213 Tennessee elementary teachers' responses to 6 organizational indexes to determine effects of school organization and administrative support on teacher commitment. Finds novices needed organizational support for behavioral management and boundary tasks, midcareer teachers needed autonomy and empowerment, whereas veterans' commitment…

Auditory working memory impairments in individuals at familial high risk for schizophrenia

PubMed Central

Seidman, Larry J.; Meyer, Eric C.; Giuliano, Anthony J.; Breiter, Hans C.; Goldstein, Jill M.; Kremen, William S.; Thermenos, Heidi W.; Toomey, Rosemary; Stone, William S.; Tsuang, Ming T.; Faraone, Stephen V.

2012-01-01

Objectives The search for predictors of schizophrenia has accelerated with a growing focus on early intervention and prevention of psychotic illness. Studying nonpsychotic relatives of individuals with schizophrenia enables identification of markers of vulnerability for the illness independent of confounds associated with psychosis. The goal of these studies was to develop new auditory continuous performance tests (ACPTs) and evaluate their effects in individuals with schizophrenia and their relatives. Methods We carried out two studies of auditory vigilance with tasks involving working memory (WM) and interference control with increasing levels of cognitive load to discern the information processing vulnerabilities in a sample of schizophrenia patients, and two samples of nonpsychotic relatives of individuals with schizophrenia and controls. Study 1 assessed adults (mean age = 41), and Study 2 assessed teenagers and young adults age 13-25 (mean =19). Results Patients with schizophrenia were impaired on all five versions of the ACPTs, while relatives were impaired only on WM tasks, particularly the two interference tasks that maximize cognitive load. Across all groups, the interference tasks were more difficult to perform than the other tasks. Schizophrenia patients performed worse than relatives who performed worse than controls. For patients, the effect sizes were large (Cohen’s d =1.5), whereas for relatives, they were moderate (d = ~0.40-0.50). There was no age by group interaction in the relatives –control comparison except for participants <31 years of age. Conclusions Novel WM tasks that manipulate cognitive load and interference control index an important component of the vulnerability to schizophrenia. PMID:22563872

Teaching Advanced SQL Skills: Text Bulk Loading

ERIC Educational Resources Information Center

Olsen, David; Hauser, Karina

2007-01-01

Studies show that advanced database skills are important for students to be prepared for today's highly competitive job market. A common task for database administrators is to insert a large amount of data into a database. This paper illustrates how an up-to-date, advanced database topic, namely bulk insert, can be incorporated into a database…

An Investigation of Sensory Information, Levels of Automation, and Piloting Experience on Unmanned Aircraft Pilot Performance

DTIC Science & Technology

2012-03-01

Development.of. NASA - TLX .(Task.Load.Index):.Results.of.empiri- cal.and.theoretical.research ..In.P .A ..Hancock.&.N .. Meshkati.(Eds .),.Human...8 Automated Manual Level of Automation Hi gh Z oo m M an ip ul at io n Pilot Non-pilot Figure 4. Number of participants with high levels of zoom

Loads and loads and loads: the influence of prospective load, retrospective load, and ongoing task load in prospective memory.

PubMed

Meier, Beat; Zimmermann, Thomas D

2015-01-01

In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load (OTL) can affect prospective memory performance. The existence of multiple target events increases prospective load (PL) and adding complexity to the to-be-remembered action increases retrospective load (RL). In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results showed an effect of PL on costs in the ongoing task for categorical targets (Experiment 2), but not for specific targets (Experiment 1). RL and OTL both affected remembering the retrospective component of the prospective memory task. We suggest that PL can enhance costs in the ongoing task due to additional monitoring requirements. RL and OTL seem to impact the division of resources between the ongoing task and retrieval of the retrospective component, which may affect disengagement from the ongoing task. In general, the results demonstrate that the different types of load affect prospective memory differentially.

Loads and loads and loads: the influence of prospective load, retrospective load, and ongoing task load in prospective memory

PubMed Central

Meier, Beat; Zimmermann, Thomas D.

2015-01-01

In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load (OTL) can affect prospective memory performance. The existence of multiple target events increases prospective load (PL) and adding complexity to the to-be-remembered action increases retrospective load (RL). In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results showed an effect of PL on costs in the ongoing task for categorical targets (Experiment 2), but not for specific targets (Experiment 1). RL and OTL both affected remembering the retrospective component of the prospective memory task. We suggest that PL can enhance costs in the ongoing task due to additional monitoring requirements. RL and OTL seem to impact the division of resources between the ongoing task and retrieval of the retrospective component, which may affect disengagement from the ongoing task. In general, the results demonstrate that the different types of load affect prospective memory differentially. PMID:26082709

Subjective evaluation of physical and mental workload interactions across different muscle groups.

PubMed

Mehta, Ranjana K; Agnew, Michael J

2015-01-01

Both physical and mental demands, and their interactions, have been shown to increase biomechanical loading and physiological reactivity as well as impair task performance. Because these interactions have shown to be muscle-dependent, the aim of this study was to determine the sensitivity of the NASA Task Load Index (NASA TLX) and Ratings of Perceived Exertion (RPE) to evaluate physical and mental workload during muscle-specific tasks. Twenty-four participants performed upper extremity and low back exertions at three physical workload levels in the absence and presence of a mental stressor. Outcome measures included RPE and NASA TLX (six sub-scales) ratings. The findings indicate that while both RPEs and NASA TLX ratings were sensitive to muscle-specific changes in physical demand, only an additional mental stressor and its interaction with either physical demand or muscle groups influenced the effort sub-scale and overall workload scores of the NASA TLX. While additional investigations in actual work settings are warranted, the NASA TLX shows promise in evaluating perceived workload that is sensitive not only to physical and mental demands but also sensitive in determining workload for tasks that employ different muscle groups.

Temporal Stress in the Operating Room: Brain Engagement Promotes "Coping" and Disengagement Prompts "Choking".

PubMed

Modi, Hemel N; Singh, Harsimrat; Orihuela-Espina, Felipe; Athanasiou, Thanos; Fiorentino, Francesca; Yang, Guang-Zhong; Darzi, Ara; Leff, Daniel R

2018-04-01

To investigate the impact of time pressure (TP) on prefrontal activation and technical performance in surgical residents during a laparoscopic suturing task. Neural mechanisms enabling surgeons to maintain performance and cope with operative stressors are unclear. The prefrontal cortex (PFC) is implicated due to its role in attention, concentration, and performance monitoring. A total of 33 residents [Postgraduate Year (PGY)1-2 = 15, PGY3-4 = 8, and PGY5 = 10] performed a laparoscopic suturing task under "self-paced" (SP) and "TP" conditions (TP = maximum 2 minutes per knot). Subjective workload was quantified using the Surgical Task Load Index. PFC activation was inferred using optical neuroimaging. Technical skill was assessed using progression scores (au), error scores (mm), leak volumes (mL), and knot tensile strengths (N). TP led to greater perceived workload amongst all residents (mean Surgical Task Load Index score ± SD: PGY1-2: SP = 160.3 ± 24.8 vs TP = 202.1 ± 45.4, P < 0.001; PGY3-4: SP = 123.0 ± 52.0 vs TP = 172.5 ± 43.1, P < 0.01; PGY5: SP = 105.8 ± 55.3 vs TP = 159.1 ± 63.1, P < 0.05). Amongst PGY1-2 and PGY3-4, deterioration in task progression, error scores and knot tensile strength (P < 0.05), and diminished PFC activation was observed under TP. In PGY5, TP resulted in inferior task progression and error scores (P < 0.05), but preservation of knot tensile strength. Furthermore, PGY5 exhibited less attenuation of PFC activation under TP, and greater activation than either PGY1-2 or PGY3-4 under both experimental conditions (P < 0.05). Senior residents cope better with temporal demands and exhibit greater technical performance stability under pressure, possibly due to sustained PFC activation and greater task engagement. Future work should seek to develop training strategies that recruit prefrontal resources, enhance task engagement, and improve performance under pressure.

Task Dependence, Tissue Specificity, and Spatial Distribution of Widespread Activations in Large Single-Subject Functional MRI Datasets at 7T

PubMed Central

Gonzalez-Castillo, Javier; Hoy, Colin W.; Handwerker, Daniel A.; Roopchansingh, Vinai; Inati, Souheil J.; Saad, Ziad S.; Cox, Robert W.; Bandettini, Peter A.

2015-01-01

It was recently shown that when large amounts of task-based blood oxygen level–dependent (BOLD) data are combined to increase contrast- and temporal signal-to-noise ratios, the majority of the brain shows significant hemodynamic responses time-locked with the experimental paradigm. Here, we investigate the biological significance of such widespread activations. First, the relationship between activation extent and task demands was investigated by varying cognitive load across participants. Second, the tissue specificity of responses was probed using the better BOLD signal localization capabilities of a 7T scanner. Finally, the spatial distribution of 3 primary response types—namely positively sustained (pSUS), negatively sustained (nSUS), and transient—was evaluated using a newly defined voxel-wise waveshape index that permits separation of responses based on their temporal signature. About 86% of gray matter (GM) became significantly active when all data entered the analysis for the most complex task. Activation extent scaled with task load and largely followed the GM contour. The most common response type was nSUS BOLD, irrespective of the task. Our results suggest that widespread activations associated with extremely large single-subject functional magnetic resonance imaging datasets can provide valuable information about the functional organization of the brain that goes undetected in smaller sample sizes. PMID:25405938

Inflight workload assessment: comparison of subjective and physiological measurements.

PubMed

Lee, Yung-Hui; Liu, Bor-Shong

2003-10-01

Assessment of pilot workload during flight is an important aviation safety consideration. The aim of this study was to assess inflight pilot workload using both physiological and multidimensional subjective-ratings measurements (heart rate and NASA Task Load Index, respectively), comparing relative sensitivity during the four phases of flight: take-off, cruise, approach, and landing. Ten male pilots volunteered to participate in the trials, which took place in a Boeing 747-400 flight simulator. Electrocardiography was performed throughout the test using the portable Cardiovis ECG system. Mean heart rate (HR) and incremental heart rate (delta HR) were considered indices of physiological workload. Peak HR was observed during take-off (83.2 bpm) and landing (88.6 bpm); moreover, delta HR was also greatest (14.2 bpm and 18.8 bpm). The Task Load Index (TLX) scale revealed that mental and performance demands were essential components of workload during flight. In addition, temporal demand was an important component of workload during take-off and physical demand was significant during cruise. Analysis of correlation revealed that the delta HR is significantly related to TLX scores (r = 0.81, n = 40). Management of the individual sources of stress, which tend to become predominant during different flight phases, should be emphasized in periodic recurrent training. For example, a pilot must be trained to cope with the increased temporal stresses associated with take-off. In addition, the recommendations will be concerned with maintaining vigilance, task allocation between pilots, and inflight rest during long-haul cruise.

Upper Limb Muscle and Brain Activity in Light Assembly Task on Different Load Levels

NASA Astrophysics Data System (ADS)

Zadry, Hilma Raimona; Dawal, Siti Zawiah Md.; Taha, Zahari

2010-10-01

A study was conducted to investigate the effect of load on upper limb muscles and brain activities in light assembly task. The task was conducted at two levels of load (Low and high). Surface electromyography (EMG) was used to measure upper limb muscle activities of twenty subjects. Electroencephalography (EEG) was simultaneously recorded with EMG to record brain activities from Fz, Pz, O1 and O2 channels. The EMG Mean Power Frequency (MPF) of the right brachioradialis and the left upper trapezius activities were higher on the high-load task compared to low-load task. The EMG MPF values also decrease as time increases, that reflects muscle fatigue. Mean power of the EEG alpha bands for the Fz-Pz channels were found to be higher on the high-load task compared to low-load task, while for the O1-O2 channels, they were higher on the low-load task than on the high-load task. These results indicated that the load levels effect the upper limb muscle and brain activities. The high-load task will increase muscle activities on the right brachioradialis and the left upper tapezius muscles, and will increase the awareness and motivation of the subjects. Whilst the low-load task can generate drowsiness earlier. It signified that the longer the time and the more heavy of the task, the subjects will be more fatigue physically and mentally.

Comparison between magnetic anchoring and guidance system camera-assisted laparoendoscopic single-site surgery nephrectomy and conventional laparoendoscopic single-site surgery nephrectomy in a porcine model: focus on ergonomics and workload profiles.

PubMed

Han, Woong Kyu; Tan, Yung K; Olweny, Ephrem O; Yin, Gang; Liu, Zhuo-Wei; Faddegon, Stephen; Scott, Daniel J; Cadeddu, Jeffrey A

2013-04-01

To compare surgeon-assessed ergonomic and workload demands of magnetic anchoring and guidance system (MAGS) laparoendoscopic single-site surgery (LESS) nephrectomy with conventional LESS nephrectomy in a porcine model. Participants included two expert and five novice surgeons who each performed bilateral LESS nephrectomy in two nonsurvival animals using either the MAGS camera or conventional laparoscope. Task difficulty and workload demands of the surgeon and camera driver were assessed using the validated National Aeronautics and Space Administration Task Load Index (NASA-TLX) questionnaire. Surgeons were also asked to score 6 parameters on a Likert scale (range 1=low/easy to 5=high/hard): procedure-associated workload, ergonomics, technical challenge, visualization, accidental events, and instrument handling. Each step of the nephrectomy was also timed and instrument clashing was quantified. Scores for each parameter on the Likert scale were significantly lower for MAGS-LESS nephrectomy. Mean number of internal and external clashes were significantly lower for the MAGS camera (p<0.001). Mean task times for each procedure were shorter for experts than for novices, but this was not statistically significant. NASA-TLX workload ratings by the surgeon and camera driver showed that MAGS resulted in a significantly lower workload than the conventional laparoscope during LESS nephrectomy (p<0.05). The use of the MAGS camera during LESS nephrectomy lowers the task workload for both the surgeon and camera driver when compared to conventional laparoscope use. Subjectively, it appears to also improve surgeons' impressions of ergonomics and technical challenge. Pending approval for clinical use, further evaluation in the clinical setting is warranted.

Subjective and objective quantification of physician's workload and performance during radiation therapy planning tasks.

PubMed

Mazur, Lukasz M; Mosaly, Prithima R; Hoyle, Lesley M; Jones, Ellen L; Marks, Lawrence B

2013-01-01

To quantify, and compare, workload for several common physician-based treatment planning tasks using objective and subjective measures of workload. To assess the relationship between workload and performance to define workload levels where performance could be expected to decline. Nine physicians performed the same 3 tasks on each of 2 cases ("easy" vs "hard"). Workload was assessed objectively throughout the tasks (via monitoring of pupil size and blink rate), and subjectively at the end of each case (via National Aeronautics and Space Administration Task Load Index; NASA-TLX). NASA-TLX assesses the 6 dimensions (mental, physical, and temporal demands, frustration, effort, and performance); scores > or ≈ 50 are associated with reduced performance in other industries. Performance was measured using participants' stated willingness to approve the treatment plan. Differences in subjective and objective workload between cases, tasks, and experience were assessed using analysis of variance (ANOVA). The correlation between subjective and objective workload measures were assessed via the Pearson correlation test. The relationships between workload and performance measures were assessed using the t test. Eighteen case-wise and 54 task-wise assessments were obtained. Subjective NASA-TLX scores (P < .001), but not time-weighted averages of objective scores (P > .1), were significantly lower for the easy vs hard case. Most correlations between the subjective and objective measures were not significant, except between average blink rate and NASA-TLX scores (r = -0.34, P = .02), for task-wise assessments. Performance appeared to decline at NASA-TLX scores of ≥55. The NASA-TLX may provide a reasonable method to quantify subjective workload for broad activities, and objective physiologic eye-based measures may be useful to monitor workload for more granular tasks within activities. The subjective and objective measures, as herein quantified, do not necessarily track each other, and more work is needed to assess their utilities. From a series of controlled experiments, we found that performance appears to decline at subjective workload levels ≥55 (as measured via NASA-TLX), which is consistent with findings from other industries. Copyright © 2013 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Gender involvement in manual material handling (mmh) tasks in agriculture and technology intervention to mitigate the resulting musculoskeletal disorders.

PubMed

Singh, Suman; Sinwal, Neelima; Rathore, Hemu

2012-01-01

The lifting and carrying of loads in agriculture on small landholdings are unavoidable. Rural communities often lack access to appropriate technologies which may result in various health hazards. The objective was to study gender participation in agricultural activities involving manual material handling tasks, to assess MSDs experienced in various MMH tasks and to evaluate traditional method and designed technology. The study was conducted on 100 agricultural workers. Data on gender participation in MMH tasks in household, animal husbandry and agriculture and resulting MSDs was gathered. Pre and post assessment of technology intervention was done for NIOSH Lifting Index, QEC, and RPE. The results revealed greater susceptibility of females to musculoskeletal problems in most of the household and animal husbandry tasks. The hand trucks designed were pushing type with power grasp handle. The respondents were advised to carry 5 kg of weight per lift instead of lifting more weight in one lift/minute while filling the hand truck. By decreasing the weight and increasing the number of lifts per minute the respondents were seen falling in green zone indicating significant reduction in NIOSH lifting index. QEC scores concluded that for filling the hand truck 5 kg of weight should be carried to keep the exposure level low.

Reliability of Triaxial Accelerometry for Measuring Load in Men's Collegiate Ice Hockey.

PubMed

Van Iterson, Erik H; Fitzgerald, John S; Dietz, Calvin C; Snyder, Eric M; Peterson, Ben J

2017-05-01

Van Iterson, EH, Fitzgerald, JS, Dietz, CC, Snyder, EM, and Peterson, BJ. Reliability of triaxial accelerometry for measuring load in men's collegiate ice hockey. J Strength Cond Res 31(5): 1305-1312, 2017-Wearable microsensor technology incorporating triaxial accelerometry is used to quantify an index of mechanical stress associated with sport-specific movements termed PlayerLoad. The test-retest reliability of PlayerLoad in the environmental setting of ice hockey is unknown. The primary aim of this study was to quantify the test-retest reliability of PlayerLoad in ice hockey players during performance of tasks simulating game conditions. Division I collegiate male ice hockey players (N = 8) wore Catapult Optimeye S5 monitors during repeat performance of 9 ice hockey tasks simulating game conditions. Ordered ice hockey tasks during repeated bouts included acceleration (forward or backward), 60% top-speed, top-speed (forward or backward), repeated shift circuit, ice coasting, slap shot, and bench sitting. Coefficient of variation (CV), intraclass correlation coefficient (ICC), and minimum difference (MD) were used to assess PlayerLoad reliability. Test-retest CVs and ICCs of PlayerLoad were as follows: 8.6% and 0.54 for forward acceleration, 13.8% and 0.78 for backward acceleration, 2.2% and 0.96 for 60% top-speed, 7.5% and 0.79 for forward top-speed, 2.8% and 0.96 for backward top-speed, 26.6% and 0.95 for repeated shift test, 3.9% and 0.68 for slap shot, 3.7% and 0.98 for coasting, and 4.1% and 0.98 for bench sitting, respectively. Raw differences between bouts were not significant for ice hockey tasks (p > 0.05). For each task, between-bout raw differences were lower vs. MD: 0.06 vs. 0.35 (forward acceleration), 0.07 vs. 0.36 (backward acceleration), 0.00 vs. 0.06 (60% top-speed), 0.03 vs. 0.20 (forward top-speed), 0.02 vs. 0.09 (backward top-speed), 0.18 vs. 0.64 (repeated shift test), 0.02 vs. 0.10 (slap shot), 0.00 vs. 0.10 (coasting), and 0.01 vs. 0.11 (bench sitting), respectively. These data suggest that PlayerLoad demonstrates moderate-to-large test-retest reliability in the environmental setting of male Division I collegiate ice hockey. Without previously testing reliability, these data are important as PlayerLoad is routinely quantified in male collegiate ice hockey to assess on ice physical activity.

User Evaluation of a Communication System That Automatically Generates Captions to Improve Telephone Communication

PubMed Central

Zekveld, Adriana A.; Kramer, Sophia E.; Kessens, Judith M.; Vlaming, Marcel S. M. G.; Houtgast, Tammo

2009-01-01

This study examined the subjective benefit obtained from automatically generated captions during telephone-speech comprehension in the presence of babble noise. Short stories were presented by telephone either with or without captions that were generated offline by an automatic speech recognition (ASR) system. To simulate online ASR, the word accuracy (WA) level of the captions was 60% or 70% and the text was presented delayed to the speech. After each test, the hearing impaired participants (n = 20) completed the NASA-Task Load Index and several rating scales evaluating the support from the captions. Participants indicated that using the erroneous text in speech comprehension was difficult and the reported task load did not differ between the audio + text and audio-only conditions. In a follow-up experiment (n = 10), the perceived benefit of presenting captions increased with an increase of WA levels to 80% and 90%, and elimination of the text delay. However, in general, the task load did not decrease when captions were presented. These results suggest that the extra effort required to process the text could have been compensated for by less effort required to comprehend the speech. Future research should aim at reducing the complexity of the task to increase the willingness of hearing impaired persons to use an assistive communication system automatically providing captions. The current results underline the need for obtaining both objective and subjective measures of benefit when evaluating assistive communication systems. PMID:19126551

Load Composition Model Workflow (BPA TIP-371 Deliverable 1A)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chassin, David P.; Cezar, Gustavo V.

This project is funded under Bonneville Power Administration (BPA) Strategic Partnership Project (SPP) 17-005 between BPA and SLAC National Accelerator Laboratory. The project in a BPA Technology Improvement Project (TIP) that builds on and validates the Composite Load Model developed by the Western Electric Coordinating Council's (WECC) Load Modeling Task Force (LMTF). The composite load model is used by the WECC Modeling and Validation Work Group to study the stability and security of the western electricity interconnection. The work includes development of load composition data sets, collection of load disturbance data, and model development and validation. This work supports reliablemore » and economic operation of the power system. This report was produced for Deliverable 1A of the BPA TIP-371 Project entitled \\TIP 371: Advancing the Load Composition Model". The deliverable documents the proposed work ow for the Composite Load Model, which provides the basis for the instrumentation, data acquisition, analysis and data dissemination activities addressed by later phases of the project.« less

Influence of pharmacological manipulations of NMDA and cholinergic receptors on working versus reference memory in a dual component odor span task.

PubMed

MacQueen, David A; Dalrymple, Savannah R; Drobes, David J; Diamond, David M

2016-06-01

Developed as a tool to assess working memory capacity in rodents, the odor span task (OST) has significant potential to advance drug discovery in animal models of psychiatric disorders. Prior investigations indicate OST performance is impaired by systemic administration of N-methyl-d-aspartate receptor (NMDA-r) antagonists and is sensitive to cholinergic manipulations. The present study sought to determine whether an impairment in OST performance can be produced by systemic administration of the competitive NMDA-r antagonist 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP; 3, 10, 17 mg/kg i.p.) in a unique dual-component variant of the OST, and whether this impairment is ameliorated by nicotine (0.75 mg/kg i.p.). Male Sprague-Dawley rats were trained to asymptotic level of performance on a 24-trial two-comparison incrementing nonmatching to sample OST. In addition, rats were administered a two-comparison olfactory reference memory (RM) task, which was integrated into the OST. The RM task provided an assessment of the effects of drug administration on global behavioral measures, long-term memory and motivation. Several measures of working memory (span, longest run, and accuracy) were dose dependently impaired by CPP without adversely affecting RM. Analysis of drug effects across trial blocks demonstrated a significant impairment of performance even at low memory loads, suggesting a CPP-induced deficit of olfactory short-term memory that is not load-dependent. Although nicotine did not ameliorate CPP-induced impairments in span or accuracy, it did block the impairment in longest run produced by the 10 mg/kg dose of CPP. Overall, our results indicate that performance in our 24 odor two-comparison OST is capacity dependent and that CPP impaired OST working, but not reference, memory. © 2016 MacQueen et al.; Published by Cold Spring Harbor Laboratory Press.

A strategy to load balancing for non-connectivity MapReduce job

NASA Astrophysics Data System (ADS)

Zhou, Huaping; Liu, Guangzong; Gui, Haixia

2017-09-01

MapReduce has been widely used in large scale and complex datasets as a kind of distributed programming model. Original Hash partitioning function in MapReduce often results the problem of data skew when data distribution is uneven. To solve the imbalance of data partitioning, we proposes a strategy to change the remaining partitioning index when data is skewed. In Map phase, we count the amount of data which will be distributed to each reducer, then Job Tracker monitor the global partitioning information and dynamically modify the original partitioning function according to the data skew model, so the Partitioner can change the index of these partitioning which will cause data skew to the other reducer that has less load in the next partitioning process, and can eventually balance the load of each node. Finally, we experimentally compare our method with existing methods on both synthetic and real datasets, the experimental results show our strategy can solve the problem of data skew with better stability and efficiency than Hash method and Sampling method for non-connectivity MapReduce task.

Evaluation of user interface and workflow design of a bedside nursing clinical decision support system.

PubMed

Yuan, Michael Juntao; Finley, George Mike; Long, Ju; Mills, Christy; Johnson, Ron Kim

2013-01-31

Clinical decision support systems (CDSS) are important tools to improve health care outcomes and reduce preventable medical adverse events. However, the effectiveness and success of CDSS depend on their implementation context and usability in complex health care settings. As a result, usability design and validation, especially in real world clinical settings, are crucial aspects of successful CDSS implementations. Our objective was to develop a novel CDSS to help frontline nurses better manage critical symptom changes in hospitalized patients, hence reducing preventable failure to rescue cases. A robust user interface and implementation strategy that fit into existing workflows was key for the success of the CDSS. Guided by a formal usability evaluation framework, UFuRT (user, function, representation, and task analysis), we developed a high-level specification of the product that captures key usability requirements and is flexible to implement. We interviewed users of the proposed CDSS to identify requirements, listed functions, and operations the system must perform. We then designed visual and workflow representations of the product to perform the operations. The user interface and workflow design were evaluated via heuristic and end user performance evaluation. The heuristic evaluation was done after the first prototype, and its results were incorporated into the product before the end user evaluation was conducted. First, we recruited 4 evaluators with strong domain expertise to study the initial prototype. Heuristic violations were coded and rated for severity. Second, after development of the system, we assembled a panel of nurses, consisting of 3 licensed vocational nurses and 7 registered nurses, to evaluate the user interface and workflow via simulated use cases. We recorded whether each session was successfully completed and its completion time. Each nurse was asked to use the National Aeronautics and Space Administration (NASA) Task Load Index to self-evaluate the amount of cognitive and physical burden associated with using the device. A total of 83 heuristic violations were identified in the studies. The distribution of the heuristic violations and their average severity are reported. The nurse evaluators successfully completed all 30 sessions of the performance evaluations. All nurses were able to use the device after a single training session. On average, the nurses took 111 seconds (SD 30 seconds) to complete the simulated task. The NASA Task Load Index results indicated that the work overhead on the nurses was low. In fact, most of the burden measures were consistent with zero. The only potentially significant burden was temporal demand, which was consistent with the primary use case of the tool. The evaluation has shown that our design was functional and met the requirements demanded by the nurses' tight schedules and heavy workloads. The user interface embedded in the tool provided compelling utility to the nurse with minimal distraction.

Effect of passive polarizing three-dimensional displays on surgical performance for experienced laparoscopic surgeons.

PubMed

Smith, R; Schwab, K; Day, A; Rockall, T; Ballard, K; Bailey, M; Jourdan, I

2014-10-01

Although the potential benefits of stereoscopic laparoscopy have been recognized for years, the technology has not been adopted because of poor operator tolerance. Passive polarizing projection systems, which have revolutionized three-dimensional (3D) cinema, are now being trialled in surgery. This study was designed to see whether this technology resulted in significant performance benefits for skilled laparoscopists. Four validated laparoscopic skills tasks, each with ten repetitions, were performed by 20 experienced laparoscopic surgeons, in both two-dimensional (2D) and 3D conditions. The primary outcome measure was the performance error rate; secondary outcome measures were time for task completion, 3D motion tracking (path length, motion smoothness and grasping frequency) and workload dimension ratings of the National Aeronautics and Space Administration (NASA) Task Load Index. Surgeons demonstrated a 62 per cent reduction in the median number of errors and a 35 per cent reduction in median performance time when using the passive polarizing 3D display compared with the 2D display. There was a significant 15 per cent reduction in median instrument path length, an enhancement of median motion smoothness, and a 15 per cent decrease in grasper frequency with the 3D display. Participants reported significant reductions in subjective workload dimension ratings of the NASA Task Load Index following use of the 3D displays. Passive polarizing 3D displays improved both the performance of experienced surgeons in a simulated setting and surgeon perception of the operative field. Although it has been argued that the experience of skilled laparoscopic surgeons compensates fully for the loss of stereopsis, this study indicates that this is not the case. Surgical relevance The potential benefits of stereoscopic laparoscopy have been known for years, but the technology has not been adopted because of poor operator tolerance. The first laparoscopic operation was carried out using a prototype passive polarizing laparoscopic system in 2010. This is new three-dimensional (3D) technology offers a real option for 3D laparoscopic surgery where previous systems have failed. This study is the first to have been carried out using this technology. It is essential that new technologies are adopted only when there is robust evidence to support their use. Currently, there are concerns about the use of robotic technologies and whether advantages exist for patient care. If there are advantages, 3D must be playing a significant role. If so, perhaps the technology under investigation here offers potential to a greater spectrum of surgeons, as well as being a more affordable option. © 2014 BJS Society Ltd. Published by John Wiley & Sons Ltd.

Working Memory in Children with Cochlear Implants: Problems are in Storage, not Processing

PubMed Central

Nittrouer, Susan; Caldwell-Tarr, Amanda; Lowenstein, Joanna H

2013-01-01

Background There is growing consensus that hearing loss and consequent amplification likely interact with cognitive systems. A phenomenon often examined in regards to these potential interactions is working memory, modeled as consisting of one component responsible for storage of information and another component responsible for processing of that information. Signal degradation associated with cochlear implants should selectively inhibit storage without affecting processing. This study examined two hypotheses: (1) A single task can be used to measure storage and processing in working memory, with recall accuracy indexing storage and rate of recall indexing processing; (2) Storage is negatively impacted for children with CIs, but not processing. Method Two experiments were conducted. Experiment 1 included adults and children, 8 and 6 years of age, with NH. Procedures tested the prediction that accuracy of recall could index storage and rate of recall could index processing. Both measures were obtained during a serial-recall task using word lists designed to manipulate storage and processing demands independently: non-rhyming nouns were the standard condition; rhyming nouns were predicted to diminish storage capacity; and non-rhyming adjectives were predicted to increase processing load. Experiment 2 included 98 8-year-olds, 48 with NH and 50 with CIs, in the same serial-recall task using the non-rhyming and rhyming nouns. Results Experiment 1 showed that recall accuracy was poorest for the rhyming nouns and rate of recall was slowest for the non-rhyming adjectives, demonstrating that storage and processing can be indexed separately within a single task. In Experiment 2, children with CIs showed less accurate recall of serial order than children with NH, but rate of recall did not differ. Recall accuracy and rate of recall were not correlated in either experiment, reflecting independence of these mechanisms. Conclusions It is possible to measure the operations of storage and processing mechanisms in working memory in a single task, and only storage is impaired for children with CIs. These findings suggest that research and clinical efforts should focus on enhancing the saliency of representation for children with CIs. Direct instruction of syntax and semantics could facilitate storage in real-world working memory tasks. PMID:24090697

Working memory in children with cochlear implants: problems are in storage, not processing.

PubMed

Nittrouer, Susan; Caldwell-Tarr, Amanda; Lowenstein, Joanna H

2013-11-01

There is growing consensus that hearing loss and consequent amplification likely interact with cognitive systems. A phenomenon often examined in regards to these potential interactions is working memory, modeled as consisting of one component responsible for storage of information and another component responsible for processing of that information. Signal degradation associated with cochlear implants should selectively inhibit storage without affecting processing. This study examined two hypotheses: (1) A single task can be used to measure storage and processing in working memory, with recall accuracy indexing storage and rate of recall indexing processing; (2) Storage is negatively impacted for children with CIs, but not processing. Two experiments were conducted. Experiment 1 included adults and children, 8 and 6 years of age, with NH. Procedures tested the prediction that accuracy of recall could index storage and rate of recall could index processing. Both measures were obtained during a serial-recall task using word lists designed to manipulate storage and processing demands independently: non-rhyming nouns were the standard condition; rhyming nouns were predicted to diminish storage capacity; and non-rhyming adjectives were predicted to increase processing load. Experiment 2 included 98 8-year-olds, 48 with NH and 50 with CIs, in the same serial-recall task using the non-rhyming and rhyming nouns. Experiment 1 showed that recall accuracy was poorest for the rhyming nouns and rate of recall was slowest for the non-rhyming adjectives, demonstrating that storage and processing can be indexed separately within a single task. In Experiment 2, children with CIs showed less accurate recall of serial order than children with NH, but rate of recall did not differ. Recall accuracy and rate of recall were not correlated in either experiment, reflecting independence of these mechanisms. It is possible to measure the operations of storage and processing mechanisms in working memory in a single task, and only storage is impaired for children with CIs. These findings suggest that research and clinical efforts should focus on enhancing the saliency of representation for children with CIs. Direct instruction of syntax and semantics could facilitate storage in real-world working memory tasks. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Selective impairment of auditory selective attention under concurrent cognitive load.

PubMed

Dittrich, Kerstin; Stahl, Christoph

2012-06-01

Load theory predicts that concurrent cognitive load impairs selective attention. For visual stimuli, it has been shown that this impairment can be selective: Distraction was specifically increased when the stimulus material used in the cognitive load task matches that of the selective attention task. Here, we report four experiments that demonstrate such selective load effects for auditory selective attention. The effect of two different cognitive load tasks on two different auditory Stroop tasks was examined, and selective load effects were observed: Interference in a nonverbal-auditory Stroop task was increased under concurrent nonverbal-auditory cognitive load (compared with a no-load condition), but not under concurrent verbal-auditory cognitive load. By contrast, interference in a verbal-auditory Stroop task was increased under concurrent verbal-auditory cognitive load but not under nonverbal-auditory cognitive load. This double-dissociation pattern suggests the existence of different and separable verbal and nonverbal processing resources in the auditory domain.

Viewing the workload of vigilance through the lenses of the NASA-TLX and the MRQ.

PubMed

Finomore, Victor S; Shaw, Tyler H; Warm, Joel S; Matthews, Gerald; Boles, David B

2013-12-01

The aim of this study was to compare the effectiveness of a new index of perceived mental workload, the Multiple Resource Questionnaire (MRQ), with the standard measure of workload used in the study of vigilance, the NASA Task Load Index (NASA-TLX). The NASA-TLX has been used extensively to demonstrate that vigilance tasks impose a high level of workload on observers. However, this instrument does not specify the information-processing resources needed for task performance. The MRQ offers a tool to measure the workload associated with vigilance assignments in which such resources can be identified. Two experiments were performed in which factors known to influence task demand were varied. Included were the detection of stimulus presence or absence, detecting critical signals by means of successive-type (absolute judgment) and simultaneous-type (comparative judgment) discriminations, and operating under multitask vs. single-task conditions. The MRQ paralleled the NASA-TLX in showing that vigilance tasks generally induce high levels of workload and that workload scores are greater in detecting stimulus absence than presence and in making successive as compared to simultaneous-type discriminations. Additionally, the MRQ was more effective than the NASA-TLX in reflecting higher workload in the context of multitask than in single-task conditions. The resource profiles obtained with MRQ fit well with the nature of the vigilance tasks employed, testifying to the scale's content validity. The MRQ may be a meaningful addition to the NASA-TLX for measuring the workload of vigilance assignments. By uncovering knowledge representation associated with different tasks, the MRQ may aid in designing operational vigilance displays.

Forced guidance and distribution of practice in sequential information processing.

NASA Technical Reports Server (NTRS)

Decker, L. R.; Rogers, C. A., Jr.

1973-01-01

Distribution of practice and forced guidance were used in a sequential information-processing task in an attempt to increase the capacity of human information-processing mechanisms. A reaction time index of the psychological refractory period was used as the response measure. Massing of practice lengthened response times while forced guidance shortened them. Interpretation was in terms of load reduction upon the response-selection stage of the information-processing system.-

Automated Design of Restraint Layer of an Inflatable Vessel

NASA Technical Reports Server (NTRS)

Spexarth, Gary

2007-01-01

A Mathcad computer program largely automates the design and analysis of the restraint layer (the primary load-bearing layer) of an inflatable vessel that consists of one or more sections having cylindrical, toroidal, and/or spherical shape(s). A restraint layer typically comprises webbing in the form of multiple straps. The design task includes choosing indexing locations along the straps, computing the load at every location in each strap, computing the resulting stretch at each location, and computing the amount of undersizing required of each strap so that, once the vessel is inflated and the straps thus stretched, the vessel can be expected to assume the desired shape. Prior to the development of this program, the design task was performed by use of a difficult-to-use spreadsheet program that required manual addition of rows and columns depending on the numbers of strap rows and columns of a given design. In contrast, this program is completely parametric and includes logic that automatically adds or deletes rows and columns as needed. With minimal input from the user, this program automatically computes indexing locations, strap lengths, undersizing requirements, and all design data required to produce detailed drawings and assembly procedures. It also generates textual comments that help the user understand the calculations.

Formulation, characterization and pharmacokinetics of praziquantel-loaded hydrogenated castor oil solid lipid nanoparticles.

PubMed

Xie, Shuyu; Pan, Baoliang; Wang, Ming; Zhu, Luyan; Wang, Fenghua; Dong, Zhao; Wang, Xiaofang; Zhou, WenZhong

2010-07-01

The purpose of this study was to formulate praziquantel (PZQ)-loaded hydrogenated castor oil (HCO) solid lipid nanoparticles (SLN) to enhance the bioavailability and prolong the systemic circulation of the drug. PZQ was encapsulated into HCO nanoparticles by a hot homogenization and ultrasonication method. The physicochemical characteristics of SLN were investigated by optical microscope, scanning electron microscopy and photon correlation spectroscopy. Pharmacokinetics were studied after oral, subcutaneous and intramuscular administration in mice. The diameter, polydispersivity index, zeta potential, encapsulation efficiency and loading capacity of the nanoparticles were 344.0 +/- 15.1 nm, 0.31 +/- 0.08, -16.7 +/- 0.5 mV, 62.17 +/- 6.53% and 12.43 +/- 1.31%, respectively. In vitro release of PZQ-loaded HCO-SLN exhibited an initial burst release followed by a sustained release. SLN increased the bioavailability of PZQ by 14.9-, 16.1- and 2.6-fold, and extended the mean residence time of the drug from 7.6, 6.6 and 8.2 to 95.9, 151.6 and 48.2 h after oral, subcutaneous and intramuscular administration, respectively. The PZQ-loaded HCO-SLN could be a promising formulation to enhance the pharmacological activity of PZQ.

Relationship between mental workload and musculoskeletal disorders among Alzahra Hospital nurses

PubMed Central

Habibi, Ehsanollah; Taheri, Mohamad Reza; Hasanzadeh, Akbar

2015-01-01

Background: Musculoskeletal disorders (MSDs) are a serious problem among the nursing staff. Mental workload is the major cause of MSDs among nursing staff. The aim of this study was to investigate the mental workload dimensions and their association with MSDs among nurses of Alzahra Hospital, affiliated to Isfahan University of Medical Sciences. Materials and Methods: This descriptive cross-sectional study was conducted on 247 randomly selected nurses who worked in the Alzahra Hospital in Isfahan, Iran in the summer of 2013. The Persian version of National Aeronautics and Space Administration Task Load Index (NASA-TLX) (measuring mental load) specialized questionnaire and Cornell Musculoskeletal Discomfort Questionnaire (CMDQ) was used for data collection. Data were collected and analyzed by Pearson correlation coefficient and Spearman correlation coefficient tests in SPSS 20. Results: Pearson and Spearman correlation tests showed a significant association between the nurses’ MSDs and the dimensions of workload frustration, total workload, temporal demand, effort, and physical demand (r = 0.304, 0.277, 0.277, 0.216, and 0.211, respectively). However, there was no significant association between the nurses’ MSDs and the dimensions of workload performance and mental demand (P > 0.05). Conclusions: The nurses’ frustration had a direct correlation with MSDs. This shows that stress is an inseparable component in hospital workplace. Thus, reduction of stress in nursing workplace should be one of the main priorities of hospital managers. PMID:25709683

Pupillary transient responses to within-task cognitive load variation.

PubMed

Wong, Hoe Kin; Epps, Julien

2016-12-01

Changes in physiological signals due to task evoked cognitive load have been reported extensively. However, pupil size based approaches for estimating cognitive load on a moment-to-moment basis are not as well understood as estimating cognitive load on a task-to-task basis, despite the appeal these approaches have for continuous load estimation. In particular, the pupillary transient response to instantaneous changes in induced load has not been experimentally quantified, and the within-task changes in pupil dilation have not been investigated in a manner that allows their consistency to be quantified with a view to biomedical system design. In this paper, a variation of the digit span task is developed which reliably induces rapid changes of cognitive load to generate task-evoked pupillary responses (TEPRs) associated with large, within-task load changes. Linear modelling and one-way ANOVA reveals that increasing the rate of cognitive loading, while keeping task demands constant, results in a steeper pupillary response. Instantaneous drops in cognitive load are shown to produce statistically significantly different transient pupillary responses relative to sustained load, and when characterised using an exponential decay response, the task-evoked pupillary response time constant is in the order of 1-5 s. Within-task test-retest analysis confirms the reliability of the moment-to-moment measurements. Based on these results, estimates of pupil diameter can be employed with considerably more confidence in moment-to-moment cognitive load estimation systems. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Validation of the NASA-TLX Score in Ongoing Assessment of Mental Workload During a Laparoscopic Learning Curve in Bariatric Surgery.

PubMed

Ruiz-Rabelo, Juan Francisco; Navarro-Rodriguez, Elena; Di-Stasi, Leandro Luigi; Diaz-Jimenez, Nelida; Cabrera-Bermon, Juan; Diaz-Iglesias, Carlos; Gomez-Alvarez, Manuel; Briceño-Delgado, Javier

2015-12-01

Fatigue and mental workload are directly associated with high-complexity tasks. In general, difficult tasks produce a higher mental workload, leaving little opportunity to deal with new/unexpected events and increasing the likelihood of performance errors. The laparoscopic Roux-en-Y gastric bypass (LRYGB) learning curve is considered to be one of the most difficult to complete in laparoscopic surgery. We wished to validate the National Aeronautics and Space Administration Task Load Index (NASA-TLX) in LRYGB and identify factors that could provoke a higher mental workload for surgeons during the learning curve. A single surgeon was enrolled to undertake 70 consecutive LRYGB procedures with two internal surgeons mentoring the first 35 cases. Patients were consecutive and ranked from case 35 to case 105 according to the date of the surgical procedure ("case rank"). Self-ratings of satisfaction, performance, and fatigue were measured at the end of surgery using a validated NASA-TLX questionnaire. The procedure was recorded for later viewing by two external evaluators. General data for patients and surgical variables were collected prospectively. A moderate correlation between the NASA-TLX score, BMI, operative time, and volumes of blood drainage was observed. There was no correlation between the NASA-TLX score and duration of hospital stay or time of drain removal. BMI ≥50 kg/m(2), male sex, inexperienced first assistant, and type 2 diabetes mellitus were identified as independent predictive factors of a higher NASA-TLX score. The NASA-TLX is a valid tool to gauge mental workload in LRYGB.

Analysis of mental workload of electrical power plant operators of control and operation centers.

PubMed

Vitório, Daiana Martins; Masculo, Francisco Soares; Melo, Miguel O B C

2012-01-01

Electrical systems can be categorized as critical systems where failure can result in significant financial loss, injury or threats to human life. The operators of the electric power control centers perform an activity in a specialized environment and have to carry it out by mobilizing knowledge and reasoning to which they have adequate training under the terms of the existing rules. To reach this there is a common mental request of personnel involved in these centers due the need to maintain attention, memory and reasoning request. In this sense, this study aims to evaluate the Mental Workload of technical workers of the Control Centers of Electrical Energy. It was undertaken a research on operators control centers of the electricity sector in Northeast Brazil. It was used for systematic observations, followed by interview and application of the instrument National Aeronautics and Space Administration Task Load Index known as NASA-TLX. As a result there will be subsidies for an assessment of mental workload of operators, and a contribution to improving the processes of managing the operation of electric utilities and the quality of workers.

Intraoperative Noise Increases Perceived Task Load and Fatigue in Anesthesiology Residents: A Simulation-Based Study.

PubMed

McNeer, Richard R; Bennett, Christopher L; Dudaryk, Roman

2016-02-01

Operating rooms are identified as being one of the noisiest of clinical environments, and intraoperative noise is associated with adverse effects on staff and patient safety. Simulation-based experiments would offer controllable and safe venues for investigating this noise problem. However, realistic simulation of the clinical auditory environment is rare in current simulators. Therefore, we retrofitted our operating room simulator to be able to produce immersive auditory simulations with the use of typical sound sources encountered during surgeries. Then, we tested the hypothesis that anesthesia residents would perceive greater task load and fatigue while being given simulated lunch breaks in noisy environments rather than in quiet ones. As a secondary objective, we proposed and tested the plausibility of a novel psychometric instrument for the assessment of stress. In this simulation-based, randomized, repeated-measures, crossover study, 2 validated psychometric survey instruments, the NASA Task Load Index (NASA-TLX), composed of 6 items, and the Swedish Occupational Fatigue Inventory (SOFI), composed of 5 items, were used to assess perceived task load and fatigue, respectively, in first-year anesthesia residents. Residents completed the psychometric instruments after being given lunch breaks in quiet and noisy intraoperative environments (soundscapes). The effects of soundscape grouping on the psychometric instruments and their comprising items were analyzed with a split-plot analysis. A model for a new psychometric instrument for measuring stress that combines the NASA-TLX and SOFI instruments was proposed, and a factor analysis was performed on the collected data to determine the model's plausibility. Twenty residents participated in this study. Multivariate analysis of variance showed an effect of soundscape grouping on the combined NASA-TLX and SOFI instrument items (P = 0.003) and the comparisons of univariate item reached significance for the NASA Temporal Demand item (P = 0.0004) and the SOFI Lack of Energy item (P = 0.001). Factor analysis extracted 4 factors, which were assigned the following construct names for model development: Psychological Task Load, Psychological Fatigue, Acute Physical Load, and Performance-Chronic Physical Load. Six of the 7 fit tests used in the partial confirmatory factor analysis were positive when we fitted the data to the proposed model, suggesting that further validation is warranted. This study provides evidence that noise during surgery can increase feelings of stress, as measured by perceived task load and fatigue levels, in anesthesiologists and adds to the growing literature pointing to an overall adverse impact of clinical noise on caregivers and patient safety. The psychometric model proposed in this study for assessing perceived stress is plausible based on factor analysis and will be useful for characterizing the impact of the clinical environment on subject stress levels in future investigations.

Cognitive task analysis: harmonizing tasks to human capacities.

PubMed

Neerincx, M A; Griffioen, E

1996-04-01

This paper presents the development of a cognitive task analysis that assesses the task load of jobs and provides indicators for the redesign of jobs. General principles of human task performance were selected and, subsequently, integrated into current task modelling techniques. The resulting cognitive task analysis centres around four aspects of task load: the number of actions in a period, the ratio between knowledge- and rule-based actions, lengthy uninterrupted actions, and momentary overloading. The method consists of three stages: (1) construction of a hierarchical task model, (2) a time-line analysis and task load assessment, and (3), if necessary, adjustment of the task model. An application of the cognitive task analysis in railway traffic control showed its benefits over the 'old' task load analysis of the Netherlands Railways. It provided a provisional standard for traffic control jobs, conveyed two load risks -- momentary overloading and underloading -- and resulted in proposals to satisfy the standard and to diminish the two load risk.

Cardiac vagal tone is correlated with selective attention to neutral distractors under load.

PubMed

Park, Gewnhi; Vasey, Michael W; Van Bavel, Jay J; Thayer, Julian F

2013-04-01

We examined whether cardiac vagal tone (indexed by heart rate variability, HRV) was associated with the functioning of selective attention under load. Participants were instructed to detect a target letter among letter strings superimposed on either fearful or neutral distractor faces. Under low load, when letter strings consisted of six target letters, there was no difference between people with high and low HRV on task performance. Under high load, when letter strings consisted of one target letter and five nontarget letters, people with high HRV were faster in trials with neutral distractors, but not with fearful distractors. However, people with low HRV were slower in trials with both fearful and neutral distractors. The current research suggests cardiac vagal tone is associated with successful control of selective attention critical for goal-directed behavior, and its impact is greater when fewer cognitive resources are available. Copyright © 2013 Society for Psychophysiological Research.

Threat distractor and perceptual load modulate test-retest reliability of anterior cingulate cortex response.

PubMed

Bunford, Nora; Kinney, Kerry L; Michael, Jamie; Klumpp, Heide

2017-07-03

Accumulating data from fMRI studies implicate the rostral anterior cingulate cortex (rACC) in inhibition of attention to threat distractors that compete with task-relevant goals for processing resources. However, little data is available on the reliability of rACC activation. Our aim in the current study was to examine test-retest reliability of rACC activation over a 12-week period, in the context of a validated emotional interference paradigm that varied in perceptual load. During functional MRI, 23 healthy volunteers completed a task involving a target letter in a string of identical letters (low load) or in a string of mixed letters (high load) superimposed on angry, fearful, and neutral face distractors. Intraclass correlation coefficients (ICCs) indicated that under low, but not high perceptual load, rACC activation to fearful vs. neutral distractors was moderately reliable. Conversely, regardless of perceptual load, rACC activation to angry vs. neutral distractors was not reliable. Regarding behavioral performance, ICCs indicated that accuracy was not reliable regardless of distractor type or perceptual load. Although reaction time (RT) was similarly not reliable regardless of distractor type under low perceptual load, RT to angry vs. neutral distractors and to fearful vs. neutral distractors was reliable under high perceptual load. Together, results indicate the test-retest reliability of rACC activation and corresponding behavioral performance are context dependent; reliability of the former varies as a function of distractor type and level of cognitive demand, whereas reliability of the latter depends on behavioral index (accuracy vs. RT) and level of cognitive demand but not distractor type. Copyright © 2017 Elsevier Inc. All rights reserved.

Relationship between workload and mind-wandering in simulated driving

PubMed Central

2017-01-01

Mental workload and mind-wandering are highly related to driving safety. This study investigated the relationship between mental workload and mind-wandering while driving. Participants (N = 40) were asked to perform a car following task in driving simulator, and report whether they had experienced mind-wandering upon hearing a tone. After driving, participants reported their workload using the NASA-Task Load Index (TLX). Results revealed an interaction between workload and mind-wandering in two different perspectives. First, there was a negative correlation between workload and mind-wandering (r = -0.459, p < 0.01) for different individuals. Second, from temporal perspective workload and mind-wandering frequency increased significantly over task time and were positively correlated. Together, these findings contribute to understanding the roles of workload and mind-wandering in driving. PMID:28467513

Glucose and the wandering mind: not paying attention or simply out of fuel?

PubMed

Birnie, L H W; Smallwood, J; Reay, J; Riby, L M

2015-08-01

The impact of raising glycaemia by ingestion of a glucose drink has revealed cognitive facilitation, particularly for memory and attention. This study aimed to extend current knowledge by examining, for the first time, whether glucose load also moderates task-related (TRT) and task-unrelated thoughts (TUT) during activities that vary in their requirement for sustained attention. A 2 (25 g glucose vs. placebo) × 2 (fast vs. slow version of the Sustained Attention to Response Task (SART)) repeated measures, counterbalanced design was used with 16 healthy adults. Self-report questionnaires probed participants' levels of TRT and TUT during SART performance. Prior to testing, the Short Imaginal Processes Inventory (SIPI) was also administered to help pinpoint the nature of thought processes during the task before and after treatment. Analysis of variance revealed no significant effect of treatment; however, we report a pattern of results that is consistent with glucose facilitation effects on task accuracy for more demanding attention tasks (d = 0.56). Additionally, glucose improved the monitoring and task reflection as measured by TRT (d = 0.33) in the more demanding task but no effect on TUT. Probing the nature of thought processes further, we also report two novel correlations (in the placebo) between fears of failure (indexed by the SIPI) and the number of TUT episodes and perceived poor attention control (indexed by the SIPI) and number of TUT and speculate that glucose may act to buffer against TUT episodes under externally demanding situations. These data extend previous research examining the glucose facilitation effect to the processing of internal thought processes.

The role of perceptual load in inattentional blindness.

PubMed

Cartwright-Finch, Ula; Lavie, Nilli

2007-03-01

Perceptual load theory offers a resolution to the long-standing early vs. late selection debate over whether task-irrelevant stimuli are perceived, suggesting that irrelevant perception depends upon the perceptual load of task-relevant processing. However, previous evidence for this theory has relied on RTs and neuroimaging. Here we tested the effects of load on conscious perception using the "inattentional blindness" paradigm. As predicted by load theory, awareness of a task-irrelevant stimulus was significantly reduced by higher perceptual load (with increased numbers of search items, or a harder discrimination vs. detection task). These results demonstrate that conscious perception of task-irrelevant stimuli critically depends upon the level of task-relevant perceptual load rather than intentions or expectations, thus enhancing the resolution to the early vs. late selection debate offered by the perceptual load theory.

The impact of physical and mental tasks on pilot mental workoad

NASA Technical Reports Server (NTRS)

Berg, S. L.; Sheridan, T. B.

1986-01-01

Seven instrument-rated pilots with a wide range of backgrounds and experience levels flew four different scenarios on a fixed-base simulator. The Baseline scenario was the simplest of the four and had few mental and physical tasks. An activity scenario had many physical but few mental tasks. The Planning scenario had few physical and many mental taks. A Combined scenario had high mental and physical task loads. The magnitude of each pilot's altitude and airspeed deviations was measured, subjective workload ratings were recorded, and the degree of pilot compliance with assigned memory/planning tasks was noted. Mental and physical performance was a strong function of the manual activity level, but not influenced by the mental task load. High manual task loads resulted in a large percentage of mental errors even under low mental task loads. Although all the pilots gave similar subjective ratings when the manual task load was high, subjective ratings showed greater individual differences with high mental task loads. Altitude or airspeed deviations and subjective ratings were most correlated when the total task load was very high. Although airspeed deviations, altitude deviations, and subjective workload ratings were similar for both low experience and high experience pilots, at very high total task loads, mental performance was much lower for the low experience pilots.

The effect of a standardised source of divided attention in airway management: A randomised, crossover, interventional manikin study.

PubMed

Prottengeier, Johannes; Petzoldt, Marlen; Jess, Nikola; Moritz, Andreas; Gall, Christine; Schmidt, Joachim; Breuer, Georg

2016-03-01

Dual-tasking, the need to divide attention between concurrent tasks, causes a severe increase in workload in emergency situations and yet there is no standardised training simulation scenario for this key difficulty. We introduced and validated a quantifiable source of divided attention and investigated its effects on performance and workload in airway management. A randomised, crossover, interventional simulation study. Center for Training and Simulation, Department of Anaesthesiology, Erlangen University Hospital, Germany. One hundred and fifty volunteer medical students, paramedics and anaesthesiologists of all levels of training. Participants secured the airway of a manikin using a supraglottic airway, conventional endotracheal intubation and video-assisted endotracheal intubation with and without the Paced Auditory Serial Addition Test (PASAT), which served as a quantifiable source of divided attention. Primary endpoint was the time for the completion of each airway task. Secondary endpoints were the number of procedural mistakes made and the perceived workload as measured by the National Aeronautics and Space Administration's task load index (NASA-TLX). This is a six-dimensional questionnaire, which assesses the perception of demands, performance and frustration with respect to a task on a scale of 0 to 100. All 150 participants completed the tests. Volunteers perceived our test to be challenging (99%) and the experience of stress and distraction true to an emergency situation (80%), but still fair (98%) and entertaining (95%). The negative effects of divided attention were reproducible in participants of all levels of expertise. Time consumption and perceived workload increased and almost half the participants make procedural mistakes under divided attention. The supraglottic airway technique was least affected by divided attention. The scenario was effective for simulation training involving divided attention in acute care medicine. The significant effects on performance and perceived workload demonstrate the validity of the model, which was also characterised by high acceptability, technical simplicity and a novel degree of standardisation.

Cognitive task load in a naval ship control centre: from identification to prediction.

PubMed

Grootjen, M; Neerincx, M A; Veltman, J A

Deployment of information and communication technology will lead to further automation of control centre tasks and an increasing amount of information to be processed. A method for establishing adequate levels of cognitive task load for the operators in such complex environments has been developed. It is based on a model distinguishing three load factors: time occupied, task-set switching, and level of information processing. Application of the method resulted in eight scenarios for eight extremes of task load (i.e. low and high values for each load factor). These scenarios were performed by 13 teams in a high-fidelity control centre simulator of the Royal Netherlands Navy. The results show that the method provides good prediction of the task load that will actually appear in the simulator. The model allowed identification of under- and overload situations showing negative effects on operator performance corresponding to controlled experiments in a less realistic task environment. Tools proposed to keep the operator at an optimum task load are (adaptive) task allocation and interface support.

Heuristic Automation for Decluttering Tactical Displays

DTIC Science & Technology

2007-01-01

order.Twenty-four of the partic- ipants were administered the NASA Task Load Index ( TLX ; Hart & Staveland, 1988; National Aeronautics and Space...each scenario, 24 of the participants rated their subjective workload using the NASA - TLX (Hart & Staveland, 1988; NASA , n.d.). The overall indices for...findings is the short-term nature of the scenar- ios . In practice, users stand watch for hours at a time, over periods of weeks and months, and significant

Pupillary Responses as a Biomarker of Diminished Effort Associated With Defeatist Attitudes and Negative Symptoms in Schizophrenia.

PubMed

Granholm, Eric; Ruiz, Ivan; Gallegos-Rodriguez, Yuliana; Holden, Jason; Link, Peter C

2016-10-15

The hypothesis that defeatist performance attitudes are associated with decreased goal-directed task effort and negative symptoms in consumers with schizophrenia was investigated by using pupillary responses as a biomarker of task effort. Pupillary dilation during cognitive tasks provides a biomarker of effort devoted to the task, with greater dilation indicating greater effort. Defeatist attitudes were assessed in 149 consumers with schizophrenia or schizoaffective disorder and 50 healthy control subjects, and consumers were divided into three groups (tertile split) with respect to severity of defeatist attitudes. Pupillary dilation responses were recorded during a digit-span task with three-, six-, and nine-digit spans. Effort allocation (pupillary responses) to the task increased as the processing load increased from low (three-digit) to moderate (six-digit) demands in healthy control subjects and consumers with schizophrenia with mild and moderate severity of defeatist attitudes. In contrast, consumers with severe defeatist attitudes did not increase their effort when processing demands increased from low to moderate loads. These consumers showed significantly less effort in the six-digit condition relative to consumers with mild defeatist attitudes. Moreover, consumers with severe defeatist attitudes showed significantly greater severity of negative symptoms relative to consumers with mild defeatist attitudes and negative symptoms were significantly correlated with defeatist attitudes. These results suggest a relationship between defeatist performance attitudes, goal-directed task effort indexed by pupillary responses, and negative symptoms in schizophrenia. The findings have implications for using cognitive therapy to reduce defeatist attitudes that may contribute to diminished effort and negative symptoms in schizophrenia. Published by Elsevier Inc.

Stimulants improve theory of mind in children with attention deficit/hyperactivity disorder.

PubMed

Maoz, Hagai; Tsviban, Lior; Gvirts, Hila Z; Shamay-Tsoory, Simone G; Levkovitz, Yechiel; Watemberg, Nathan; Bloch, Yuval

2014-03-01

Impairments in 'theory of mind' (ToM) were linked to social cognition and reciprocal relationships deficits in children with attention deficit/hyperactivity disorder (ADHD). Twenty-four children with ADHD (13 with inattentive type and 11 with combined type, mean age 10.2 years) completed the Interpersonal Reactivity Index (IRI), a self-reported empathy questionnaire. All children performed the 'faux pas' task and a computerized ToM task in two different sessions either with or without administration of methylphenidate (MPH). Administration of MPH was associated with an improvement in cognitive and affective ToM. Children with ADHD-combined type had significantly lower scores in total IRI and the fantasy scale compared to children with ADHD-inattentive type. We conclude that deficits in empathy and ToM may play an important role in the impairments in social cognition and peer relationship in children with ADHD, especially children a hyperactive component. Stimulants may improve ToM and empathic functions. Future studies including larger samples and additional cognitive tasks are warranted in order to generalize these results and to identify possible underlying mechanisms for improvement in ToM following the administration of MPH.

Auditory working memory load impairs visual ventral stream processing: toward a unified model of attentional load.

PubMed

Klemen, Jane; Büchel, Christian; Bühler, Mira; Menz, Mareike M; Rose, Michael

2010-03-01

Attentional interference between tasks performed in parallel is known to have strong and often undesired effects. As yet, however, the mechanisms by which interference operates remain elusive. A better knowledge of these processes may facilitate our understanding of the effects of attention on human performance and the debilitating consequences that disruptions to attention can have. According to the load theory of cognitive control, processing of task-irrelevant stimuli is increased by attending in parallel to a relevant task with high cognitive demands. This is due to the relevant task engaging cognitive control resources that are, hence, unavailable to inhibit the processing of task-irrelevant stimuli. However, it has also been demonstrated that a variety of types of load (perceptual and emotional) can result in a reduction of the processing of task-irrelevant stimuli, suggesting a uniform effect of increased load irrespective of the type of load. In the present study, we concurrently presented a relevant auditory matching task [n-back working memory (WM)] of low or high cognitive load (1-back or 2-back WM) and task-irrelevant images at one of three object visibility levels (0%, 50%, or 100%). fMRI activation during the processing of the task-irrelevant visual stimuli was measured in the lateral occipital cortex and found to be reduced under high, compared to low, WM load. In combination with previous findings, this result is suggestive of a more generalized load theory, whereby cognitive load, as well as other types of load (e.g., perceptual), can result in a reduction of the processing of task-irrelevant stimuli, in line with a uniform effect of increased load irrespective of the type of load.

Production practices affecting worker task demands in concrete operations: A case study.

PubMed

Memarian, Babak; Mitropoulos, Panagiotis

2015-01-01

Construction work involves significant physical, mental, and temporal task demands. Excessive task demands can have negative consequences for safety, errors and production. This exploratory study investigates the magnitude and sources of task demands on a concrete operation, and examines the effect of the production practices on the workers' task demands. The NASA Task Load Index was used to measure the perceived task demands of two work crews. The operation involved the construction of a cast-in-place concrete building under high schedule pressures. Interviews with each crew member were used to identify the main sources of the perceived demands. Extensive field observations and interviews with the supervisors and crews identified the production practices. The workers perceived different level of task demands depending on their role. The production practices influenced the task demands in two ways: (1) practices related to work organization, task design, resource management, and crew management mitigated the task demands; and (2) other practices related to work planning and crew management increased the crew's ability to cope with and adapt to high task demands. The findings identify production practices that regulate the workers' task demands. The effect of task demands on performance is mitigated by the ability to cope with high demands.

Effects of the Administration's Fiscal Year 1984 Budget on Children and Youth. Hearing before the Task Force on Entitlements, Uncontrollables, and Indexing of the Committee on the Budget. House of Representatives, Ninety-Eighth Congress, First Session (March 9, 1983). Serial No. TF8-4.

ERIC Educational Resources Information Center

Congress of the U.S., Washington, DC. House Committee on the Budget.

In this report of a hearing on the effects on children and youth of President Reagan's proposed budget cuts of means-tested entitlement programs, Linda S. McMahon, Associate Commissioner of the Office of Family Assistance, and Robert E. Leard, Acting Administrator of the Food and Nutrition Service at the Department of Agriculture, present the…

Respiratory sinus arrhythmia as a measure of cognitive workload.

PubMed

Muth, Eric R; Moss, Jason D; Rosopa, Patrick J; Salley, James N; Walker, Alexander D

2012-01-01

The current standard for measuring cognitive workload is the NASA Task-load Index (TLX) questionnaire. Although this measure has a high degree of reliability, diagnosticity, and sensitivity, a reliable physiological measure of cognitive workload could provide a non-invasive, objective measure of workload that could be tracked in real or near real-time without interrupting the task. This study investigated changes in respiratory sinus arrhythmia (RSA) during seven different sub-sections of a proposed selection test for Navy aviation and compared them to changes reported on the NASA-TLX. 201 healthy participants performed the seven tasks of the Navy's Performance Based Measure. RSA was measured during each task and the NASA-TLX was administered after each task. Multi-level modeling revealed that RSA significantly predicted NASA-TLX scores. A moderate within-subject correlation was also found between RSA and NASA TLX scores. The findings support the potential development of RSA as a real-time measure of cognitive workload. Copyright © 2011. Published by Elsevier B.V.

Mental Workload during Brain-Computer Interface Training

PubMed Central

Felton, Elizabeth A.; Williams, Justin C.; Vanderheiden, Gregg C.; Radwin, Robert G.

2012-01-01

It is not well understood how people perceive the difficulty of performing brain-computer interface (BCI) tasks, which specific aspects of mental workload contribute the most, and whether there is a difference in perceived workload between participants who are able-bodied and disabled. This study evaluated mental workload using the NASA Task Load Index (TLX), a multi-dimensional rating procedure with six subscales: Mental Demands, Physical Demands, Temporal Demands, Performance, Effort, and Frustration. Able-bodied and motor disabled participants completed the survey after performing EEG-based BCI Fitts’ law target acquisition and phrase spelling tasks. The NASA-TLX scores were similar for able-bodied and disabled participants. For example, overall workload scores (range 0 – 100) for 1D horizontal tasks were 48.5 (SD = 17.7) and 46.6 (SD 10.3), respectively. The TLX can be used to inform the design of BCIs that will have greater usability by evaluating subjective workload between BCI tasks, participant groups, and control modalities. PMID:22506483

Sex differences in verbal working memory performance emerge at very high loads of common neuroimaging tasks.

PubMed

Reed, Jessica L; Gallagher, Natalie M; Sullivan, Marie; Callicott, Joseph H; Green, Adam E

2017-04-01

Working memory (WM) supports a broad range of intelligent cognition and has been the subject of rich cognitive and neural characterization. However, the highest ranges of WM have not been fully characterized, especially for verbal information. Tasks developed to test multiple levels of WM demand (load) currently predominate brain-based WM research. These tasks are typically used at loads that allow most healthy participants to perform well, which facilitates neuroimaging data collection. Critically, however, high performance at lower loads may obscure differences that emerge at higher loads. A key question not yet addressed at high loads concerns the effect of sex. Thoroughgoing investigation of high-load verbal WM is thus timely to test for potential hidden effects, and to provide behavioral context for effects of sex observed in WM-related brain structure and function. We tested 111 young adults, matched on genotype for the WM-associated COMT-Val 108/158 Met polymorphism, on three classic WM tasks using verbal information. Each task was tested at four WM loads, including higher loads than those used in previous studies of sex differences. All tasks loaded on a single factor, enabling comparison of verbal WM ability at a construct level. Results indicated sex effects at high loads across tasks and within each task, such that males had higher accuracy, even among groups that were matched for performance at lower loads. Published by Elsevier Inc.

Dilution: A Theoretical Burden or Just Load? A Reply to Tsal and Benoni (2010)

ERIC Educational Resources Information Center

Lavie, Nilli; Torralbo, Ana

2010-01-01

Load theory of attention proposes that distractor processing is reduced in tasks with high perceptual load that exhaust attentional capacity within task-relevant processing. In contrast, tasks of low perceptual load leave spare capacity that spills over, resulting in the perception of task-irrelevant, potentially distracting stimuli. Tsal and…

The fate of task-irrelevant visual motion: perceptual load versus feature-based attention.

PubMed

Taya, Shuichiro; Adams, Wendy J; Graf, Erich W; Lavie, Nilli

2009-11-18

We tested contrasting predictions derived from perceptual load theory and from recent feature-based selection accounts. Observers viewed moving, colored stimuli and performed low or high load tasks associated with one stimulus feature, either color or motion. The resultant motion aftereffect (MAE) was used to evaluate attentional allocation. We found that task-irrelevant visual features received less attention than co-localized task-relevant features of the same objects. Moreover, when color and motion features were co-localized yet perceived to belong to two distinct surfaces, feature-based selection was further increased at the expense of object-based co-selection. Load theory predicts that the MAE for task-irrelevant motion would be reduced with a higher load color task. However, this was not seen for co-localized features; perceptual load only modulated the MAE for task-irrelevant motion when this was spatially separated from the attended color location. Our results suggest that perceptual load effects are mediated by spatial selection and do not generalize to the feature domain. Feature-based selection operates to suppress processing of task-irrelevant, co-localized features, irrespective of perceptual load.

How does cognitive load influence speech perception? An encoding hypothesis.

PubMed

Mitterer, Holger; Mattys, Sven L

2017-01-01

Two experiments investigated the conditions under which cognitive load exerts an effect on the acuity of speech perception. These experiments extend earlier research by using a different speech perception task (four-interval oddity task) and by implementing cognitive load through a task often thought to be modular, namely, face processing. In the cognitive-load conditions, participants were required to remember two faces presented before the speech stimuli. In Experiment 1, performance in the speech-perception task under cognitive load was not impaired in comparison to a no-load baseline condition. In Experiment 2, we modified the load condition minimally such that it required encoding of the two faces simultaneously with the speech stimuli. As a reference condition, we also used a visual search task that in earlier experiments had led to poorer speech perception. Both concurrent tasks led to decrements in the speech task. The results suggest that speech perception is affected even by loads thought to be processed modularly, and that, critically, encoding in working memory might be the locus of interference.

Cognitive load selectively influences the interruptive effect of pain on attention.

PubMed

Moore, David J; Eccleston, Christopher; Keogh, Edmund

2017-10-01

Pain is known to interrupt attentional performance. Such interference effects seem to occur preferentially for tasks that are complex and/or difficult. However, few studies have directly manipulated memory load in the context of pain interference to test this view. Therefore, this study examines the effect of experimental manipulations of both memory load and pain on 3 tasks previously found to be sensitive to pain interference. Three experiments were conducted. A different task was examined in each experiment, each comprising of a high- and low-cognitive load versions of the task. Experiment 1 comprised an attention span (n-back) task, experiment 2 an attention switching task, and experiment 3 a divided attention task. Each task was conducted under painful and nonpainful conditions. Within the pain condition, an experimental thermal pain induction protocol was administered at the same time participants completed the task. The load manipulations were successful in all experiments. Pain-related interference occurred under the high-load condition but only for the attention span task. No effect of pain was found on either the attentional switching or divided attention task. These results suggest that while cognitive load may influence the interruptive effect of pain on attention, this effect may be selective. Because pain affected the high-load version of the n-back task but did not interrupt performance on attentional switching or dual-task paradigms, this means that our findings did not completely support our hypotheses. Future research should explore further the parameters and conditions under which pain-related interference occurs.

Graduate Student WAIS-III Scoring Accuracy Is a Function of Full Scale IQ and Complexity of Examiner Tasks

ERIC Educational Resources Information Center

Hopwood, Christopher J.; Richard, David C. S.

2005-01-01

Research on the Wechsler Adult Intelligence Scale-Revised and Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) suggests that practicing clinical psychologists and graduate students make item-level scoring errors that affect IQ, index, and subtest scores. Studies have been limited in that Full-Scale IQ (FSIQ) and examiner administration,…

A quantitative measure for degree of automation and its relation to system performance and mental load.

PubMed

Wei, Z G; Macwan, A P; Wieringa, P A

1998-06-01

In this paper we quantitatively model degree of automation (DofA) in supervisory control as a function of the number and nature of tasks to be performed by the operator and automation. This model uses a task weighting scheme in which weighting factors are obtained from task demand load, task mental load, and task effect on system performance. The computation of DofA is demonstrated using an experimental system. Based on controlled experiments using operators, analyses of the task effect on system performance, the prediction and assessment of task demand load, and the prediction of mental load were performed. Each experiment had a different DofA. The effect of a change in DofA on system performance and mental load was investigated. It was found that system performance became less sensitive to changes in DofA at higher levels of DofA. The experimental data showed that when the operator controlled a partly automated system, perceived mental load could be predicted from the task mental load for each task component, as calculated by analyzing a situation in which all tasks were manually controlled. Actual or potential applications of this research include a methodology to balance and optimize the automation of complex industrial systems.

A physical workload index to evaluate a safe resident handling program for nursing home personnel.

PubMed

Kurowski, Alicia; Buchholz, Bryan; Punnett, Laura

2014-06-01

The aim of this study was to obtain a comprehensive analysis of the physical workload of clinical staff in long-term care facilities, before and after a safe resident handling program (SRHP). Ergonomic exposures of health care workers include manual handling of patients and many non-neutral postures. A comprehensive assessment requires the integration of loads from these varied exposures into a single metric. The Postures, Activities, Tools, and Handling observational protocol, customized for health care, was used for direct observations of ergonomic exposures in clinical jobs at 12 nursing homes before the SRHP and 3, 12, 24, and 36 months afterward. Average compressive forces on the spine were estimated for observed combinations of body postures and manual handling and then weighted by frequencies of observed time for the combination. These values were summed to obtain a biomechanical index for nursing assistants and nurses across observation periods. The physical workload index (PWI) was much higher for nursing assistants than for nurses and decreased more after 3 years (-24% versus -2.5%). Specifically during resident handling, the PWI for nursing assistants decreased by 41% of baseline value. Spinal loading was higher for nursing assistants than for nurses in long-term care centers. Both job groups experienced reductions in physical loading from the SRHP, especially the nursing assistants and especially while resident handling. The PWI facilitates a comprehensive investigation of physical loading from both manual handling and non-neutral postures. It can be used in any work setting to identify high-risk tasks and determine whether reductions in one exposure are offset by increases in another.

Chronotype, sleep loss, and diurnal pattern of salivary cortisol in a simulated daylong driving.

PubMed

Oginska, Halszka; Fafrowicz, Magdalena; Golonka, Krystyna; Marek, Tadeusz; Mojsa-Kaja, Justyna; Tucholska, Kinga

2010-07-01

The study focused on chronotype-related differences in subjective load assessment, sleepiness, and salivary cortisol pattern in subjects performing daylong simulated driving. Individual differences in work stress appraisal and psychobiological cost of prolonged load seem to be of importance in view of expanding compressed working time schedules. Twenty-one healthy, male volunteers (mean +/- SD: 27.9 +/- 4.9 yrs) were required to stay in semiconstant routine conditions. They performed four sessions (each lasting approximately 2.5 h) of simulated driving, i.e., completed chosen tasks from computer driving games. Saliva samples were collected after each driving session, i.e., at 10:00-11:00, 14:00-15:00, 18:00-19:00, and 22:00-23:00 h as well as 10-30 min after waking (between 05:00 and 06:00 h) and at bedtime (after 00:00 h). Two subgroups of subjects were distinguished on the basis of the Chronotype Questionnaire: morning (M)- and evening (E)-oriented types. Subjective data on sleep need, sleeping time preferences, sleeping problems, and the details of the preceding night were investigated by questionnaire. Subjective measures of task load (NASA Task Load Index [NASA-TLX]), activation (Thayer's Activation-Deactivation Adjective Check List [AD ACL]), and sleepiness (Karolinska Sleepiness Scale [KSS]) were applied at times of saliva samples collection. M- and E-oriented types differed significantly as to their ideal sleep length (6 h 54 min +/- 44 versus 8 h 13 min +/- 50 min), preferred sleep timing (midpoint at 03:19 versus 04:26), and sleep index, i.e., 'real-to-ideal' sleep ratio, before the experimental day (0.88 versus 0.67). Sleep deficit proved to be integrated with eveningness. M and E types exhibited similar diurnal profiles of energy, tiredness, tension, and calmness assessed by AD ACL, but E types estimated higher their workload (NASA-TLX) and sleepiness (KSS). M types exhibited a trend of higher mean cortisol levels than E types (F = 4.192, p < .056) and distinct diurnal variation (F = 2.950, p < .019), whereas E types showed a flattened diurnal curve. Cortisol values did not correlate with subjective assessments of workload, arousal, or sleepiness at any time-of-day. Diurnal cortisol pattern parameters (i.e., morning level, mean level, and range of diurnal changes) showed significant positive correlations with sleep length before the experiment (r = .48, .54, and .53, respectively) and with sleep index (r = .63, .64, and .56, respectively). The conclusions of this study are: (i) E-oriented types showed lower salivary cortisol levels and a flattened diurnal curve in comparison with M types; (ii) sleep loss was associated with lower morning cortisol and mean diurnal level, whereas higher cortisol levels were observed in rested individuals. In the context of stress theory, it may be hypothesized that rested subjects perceived the driving task as a challenge, whereas those with reduced sleep were not challenged, but bored/exhausted with the experimental situation.

E-learning, dual-task, and cognitive load: The anatomy of a failed experiment.

PubMed

Van Nuland, Sonya E; Rogers, Kem A

2016-01-01

The rising popularity of commercial anatomy e-learning tools has been sustained, in part, due to increased annual enrollment and a reduction in laboratory hours across educational institutions. While e-learning tools continue to gain popularity, the research methodologies used to investigate their impact on learning remain imprecise. As new user interfaces are introduced, it is critical to understand how functionality can influence the load placed on a student's memory resources, also known as cognitive load. To study cognitive load, a dual-task paradigm wherein a learner performs two tasks simultaneously is often used, however, its application within educational research remains uncommon. Using previous paradigms as a guide, a dual-task methodology was developed to assess the cognitive load imposed by two commercial anatomical e-learning tools. Results indicate that the standard dual-task paradigm, as described in the literature, is insensitive to the cognitive load disparities across e-learning tool interfaces. Confounding variables included automation of responses, task performance tradeoff, and poor understanding of primary task cognitive load requirements, leading to unreliable quantitative results. By modifying the secondary task from a basic visual response to a more cognitively demanding task, such as a modified Stroop test, the automation of secondary task responses can be reduced. Furthermore, by recording baseline measures for the primary task as well as the secondary task, it is possible for task performance tradeoff to be detected. Lastly, it is imperative that the cognitive load of the primary task be designed such that it does not overwhelm the individual's ability to learn new material. © 2015 American Association of Anatomists.

Visual Distractors Disrupt Audiovisual Integration Regardless of Stimulus Complexity

PubMed Central

Gibney, Kyla D.; Aligbe, Enimielen; Eggleston, Brady A.; Nunes, Sarah R.; Kerkhoff, Willa G.; Dean, Cassandra L.; Kwakye, Leslie D.

2017-01-01

The intricate relationship between multisensory integration and attention has been extensively researched in the multisensory field; however, the necessity of attention for the binding of multisensory stimuli remains contested. In the current study, we investigated whether diverting attention from well-known multisensory tasks would disrupt integration and whether the complexity of the stimulus and task modulated this interaction. A secondary objective of this study was to investigate individual differences in the interaction of attention and multisensory integration. Participants completed a simple audiovisual speeded detection task and McGurk task under various perceptual load conditions: no load (multisensory task while visual distractors present), low load (multisensory task while detecting the presence of a yellow letter in the visual distractors), and high load (multisensory task while detecting the presence of a number in the visual distractors). Consistent with prior studies, we found that increased perceptual load led to decreased reports of the McGurk illusion, thus confirming the necessity of attention for the integration of speech stimuli. Although increased perceptual load led to longer response times for all stimuli in the speeded detection task, participants responded faster on multisensory trials than unisensory trials. However, the increase in multisensory response times violated the race model for no and low perceptual load conditions only. Additionally, a geometric measure of Miller’s inequality showed a decrease in multisensory integration for the speeded detection task with increasing perceptual load. Surprisingly, we found diverging changes in multisensory integration with increasing load for participants who did not show integration for the no load condition: no changes in integration for the McGurk task with increasing load but increases in integration for the detection task. The results of this study indicate that attention plays a crucial role in multisensory integration for both highly complex and simple multisensory tasks and that attention may interact differently with multisensory processing in individuals who do not strongly integrate multisensory information. PMID:28163675

Visual Distractors Disrupt Audiovisual Integration Regardless of Stimulus Complexity.

PubMed

Gibney, Kyla D; Aligbe, Enimielen; Eggleston, Brady A; Nunes, Sarah R; Kerkhoff, Willa G; Dean, Cassandra L; Kwakye, Leslie D

2017-01-01

The intricate relationship between multisensory integration and attention has been extensively researched in the multisensory field; however, the necessity of attention for the binding of multisensory stimuli remains contested. In the current study, we investigated whether diverting attention from well-known multisensory tasks would disrupt integration and whether the complexity of the stimulus and task modulated this interaction. A secondary objective of this study was to investigate individual differences in the interaction of attention and multisensory integration. Participants completed a simple audiovisual speeded detection task and McGurk task under various perceptual load conditions: no load (multisensory task while visual distractors present), low load (multisensory task while detecting the presence of a yellow letter in the visual distractors), and high load (multisensory task while detecting the presence of a number in the visual distractors). Consistent with prior studies, we found that increased perceptual load led to decreased reports of the McGurk illusion, thus confirming the necessity of attention for the integration of speech stimuli. Although increased perceptual load led to longer response times for all stimuli in the speeded detection task, participants responded faster on multisensory trials than unisensory trials. However, the increase in multisensory response times violated the race model for no and low perceptual load conditions only. Additionally, a geometric measure of Miller's inequality showed a decrease in multisensory integration for the speeded detection task with increasing perceptual load. Surprisingly, we found diverging changes in multisensory integration with increasing load for participants who did not show integration for the no load condition: no changes in integration for the McGurk task with increasing load but increases in integration for the detection task. The results of this study indicate that attention plays a crucial role in multisensory integration for both highly complex and simple multisensory tasks and that attention may interact differently with multisensory processing in individuals who do not strongly integrate multisensory information.

Effect of perceptual load on semantic access by speech in children.

PubMed

Jerger, Susan; Damian, Markus F; Mills, Candice; Bartlett, James; Tye-Murray, Nancy; Abdi, Hervé

2013-04-01

To examine whether semantic access by speech requires attention in children. Children (N = 200) named pictures and ignored distractors on a cross-modal (distractors: auditory-no face) or multimodal (distractors: auditory-static face and audiovisual-dynamic face) picture word task. The cross-modal task had a low load, and the multimodal task had a high load (i.e., respectively naming pictures displayed on a blank screen vs. below the talker's face on his T-shirt). Semantic content of distractors was manipulated to be related vs. unrelated to the picture (e.g., picture "dog" with distractors "bear" vs. "cheese"). If irrelevant semantic content manipulation influences naming times on both tasks despite variations in loads, Lavie's (2005) perceptual load model proposes that semantic access is independent of capacity-limited attentional resources; if, however, irrelevant content influences naming only on the cross-modal task (low load), the perceptual load model proposes that semantic access is dependent on attentional resources exhausted by the higher load task. Irrelevant semantic content affected performance for both tasks in 6- to 9-year-olds but only on the cross-modal task in 4- to 5-year-olds. The addition of visual speech did not influence results on the multimodal task. Younger and older children differ in dependence on attentional resources for semantic access by speech.

Laparoendoscopic single site (LESS) in vivo suturing using a magnetic anchoring and guidance system (MAGS) camera in a porcine model: impact on ergonomics and workload.

PubMed

Yin, Gang; Han, Woong Kyu; Faddegon, Stephen; Tan, Yung Khan; Liu, Zhuo-Wei; Olweny, Ephrem O; Scott, Daniel J; Cadeddu, Jeffrey A

2013-01-01

To compare the ergonomics and workload of the surgeon during single-site suturing while using the magnetic anchoring and guidance system (MAGS) camera vs a conventional laparoscope. Seven urologic surgeons were enrolled and divided into an expert group (n=2) and a novice group (n=5) according to their laparoendoscopic single-site (LESS) experience. Each surgeon performed 2 conventional LESS and 2 MAGS camera-assisted LESS vesicostomy closures in a porcine model. A Likert scale (scoring 1-5) questionnaire assessing workload, ergonomics, technical difficulty, visualization, and needle handling, as well as a validated National Aeronautics and Space Administration Task Load Index (NASA-TLX) questionnaire were used to evaluate the tasks and workloads. MAGS LESS suturing was universally favored by expert and novice surgeons compared with conventional LESS in workload (3.4 vs 4.2), ergonomics (3.4 vs 4.4), technical challenge (3.3 vs 4.3), visualization (2.4 vs 3.3), and needle handling (3.1 vs 3.9 respectively; P<.05 for all categories). Surgeon NASA-TLX assessments found MAGS LESS suturing significantly decreased the workload in physical demand (P=.004), temporal demand (P=.017), and effort (P=.006). External instrument clashing was significantly reduced in MAGS LESS suturing (P<.001). The total operative time of MAGS LESS suturing was comparable to that of conventional LESS (P=.89). MAGS camera technology significantly decreased surgeon workload and improved ergonomics. Nevertheless, LESS suturing and knot tying remains a challenging task that requires training, regardless of which camera is used. Copyright © 2013 Elsevier Inc. All rights reserved.

Assessment of operators’ mental workload using physiological and subjective measures in cement, city traffic and power plant control centers

PubMed Central

Fallahi, Majid; Motamedzade, Majid; Heidarimoghadam, Rashid; Soltanian, Ali Reza; Miyake, Shinji

2016-01-01

Background: The present study aimed to evaluate the operators’ mental workload (MW) of cement, city traffic control and power plant control centers using subjective and objective measures during system vital parameters monitoring. Methods: This cross-sectional study was conducted from June 2014 to February 2015 at the cement, city traffic control and power plant control centers. Electrocardiography and electroencephalography data were recorded from forty males during performing their daily working in resting, low mental workload (LMW), high mental workload (HMW) and recovery conditions (each block 5 minutes). The NASA-Task Load Index (TLX) was used to evaluate the subjective workload of the operators. Results: The results showed that increasing MW had a significant effect on the operators subjective responses in two conditions ([1,53] = 216.303, P < 0.001, η2 = 0.803). Also,the Task-MW interaction effect on operators subjective responses was significant (F [3, 53] = 12.628,P < 0.001, η2 = 0.417). Analysis of repeated measures analysis of variance (ANOVA) indicated that increasing mental demands had a significant effect on heart rate, low frequency/high frequency ratio, theta and alpha band activity. Conclusion: The results suggested that when operators’ mental demands especially in traffic control and power plant tasks increased, their mental fatigue and stress level increased and their mental health deteriorated. Therefore, it may be necessary to implement an ergonomic program or administrative control to manage mental probably health in these control centers. Furthermore, by evaluating MW, the control center director can organize the human resources for each MW condition to sustain the appropriate performance as well as improve system functions. PMID:27386425

Assessment of operators' mental workload using physiological and subjective measures in cement, city traffic and power plant control centers.

PubMed

Fallahi, Majid; Motamedzade, Majid; Heidarimoghadam, Rashid; Soltanian, Ali Reza; Miyake, Shinji

2016-01-01

The present study aimed to evaluate the operators' mental workload (MW) of cement, city traffic control and power plant control centers using subjective and objective measures during system vital parameters monitoring. This cross-sectional study was conducted from June 2014 to February 2015 at the cement, city traffic control and power plant control centers. Electrocardiography and electroencephalography data were recorded from forty males during performing their daily working in resting, low mental workload (LMW), high mental workload (HMW) and recovery conditions (each block 5 minutes). The NASA-Task Load Index (TLX) was used to evaluate the subjective workload of the operators. The results showed that increasing MW had a significant effect on the operators subjective responses in two conditions ([1,53] = 216.303, P < 0.001, η2 = 0.803). Also,the Task-MW interaction effect on operators subjective responses was significant (F [3, 53] = 12.628,P < 0.001, η2 = 0.417). Analysis of repeated measures analysis of variance (ANOVA) indicated that increasing mental demands had a significant effect on heart rate, low frequency/high frequency ratio, theta and alpha band activity. The results suggested that when operators' mental demands especially in traffic control and power plant tasks increased, their mental fatigue and stress level increased and their mental health deteriorated. Therefore, it may be necessary to implement an ergonomic program or administrative control to manage mental probably health in these control centers. Furthermore, by evaluating MW, the control center director can organize the human resources for each MW condition to sustain the appropriate performance as well as improve system functions.

Systematic review of measurement tools to assess surgeons' intraoperative cognitive workload.

PubMed

Dias, R D; Ngo-Howard, M C; Boskovski, M T; Zenati, M A; Yule, S J

2018-04-01

Surgeons in the operating theatre deal constantly with high-demand tasks that require simultaneous processing of a large amount of information. In certain situations, high cognitive load occurs, which may impact negatively on a surgeon's performance. This systematic review aims to provide a comprehensive understanding of the different methods used to assess surgeons' cognitive load, and a critique of the reliability and validity of current assessment metrics. A search strategy encompassing MEDLINE, Embase, Web of Science, PsycINFO, ACM Digital Library, IEEE Xplore, PROSPERO and the Cochrane database was developed to identify peer-reviewed articles published from inception to November 2016. Quality was assessed by using the Medical Education Research Study Quality Instrument (MERSQI). A summary table was created to describe study design, setting, specialty, participants, cognitive load measures and MERSQI score. Of 391 articles retrieved, 84 met the inclusion criteria, totalling 2053 unique participants. Most studies were carried out in a simulated setting (59 studies, 70 per cent). Sixty studies (71 per cent) used self-reporting methods, of which the NASA Task Load Index (NASA-TLX) was the most commonly applied tool (44 studies, 52 per cent). Heart rate variability analysis was the most used real-time method (11 studies, 13 per cent). Self-report instruments are valuable when the aim is to assess the overall cognitive load in different surgical procedures and assess learning curves within competence-based surgical education. When the aim is to assess cognitive load related to specific operative stages, real-time tools should be used, as they allow capture of cognitive load fluctuation. A combination of both subjective and objective methods might provide optimal measurement of surgeons' cognition. © 2018 BJS Society Ltd Published by John Wiley & Sons Ltd.

Perceptual load in sport and the heuristic value of the perceptual load paradigm in examining expertise-related perceptual-cognitive adaptations.

PubMed

Furley, Philip; Memmert, Daniel; Schmid, Simone

2013-03-01

In two experiments, we transferred perceptual load theory to the dynamic field of team sports and tested the predictions derived from the theory using a novel task and stimuli. We tested a group of college students (N = 33) and a group of expert team sport players (N = 32) on a general perceptual load task and a complex, soccer-specific perceptual load task in order to extend the understanding of the applicability of perceptual load theory and further investigate whether distractor interference may differ between the groups, as the sport-specific processing task may not exhaust the processing capacity of the expert participants. In both, the general and the specific task, the pattern of results supported perceptual load theory and demonstrates that the predictions of the theory also transfer to more complex, unstructured situations. Further, perceptual load was the only determinant of distractor processing, as we neither found expertise effects in the general perceptual load task nor the sport-specific task. We discuss the heuristic utility of using response-competition paradigms for studying both general and domain-specific perceptual-cognitive adaptations.

Advanced aircraft service life monitoring method via flight-by-flight load spectra

NASA Astrophysics Data System (ADS)

Lee, Hongchul

This research is an effort to understand current method and to propose an advanced method for Damage Tolerance Analysis (DTA) for the purpose of monitoring the aircraft service life. As one of tasks in the DTA, the current indirect Individual Aircraft Tracking (IAT) method for the F-16C/D Block 32 does not properly represent changes in flight usage severity affecting structural fatigue life. Therefore, an advanced aircraft service life monitoring method based on flight-by-flight load spectra is proposed and recommended for IAT program to track consumed fatigue life as an alternative to the current method which is based on the crack severity index (CSI) value. Damage Tolerance is one of aircraft design philosophies to ensure that aging aircrafts satisfy structural reliability in terms of fatigue failures throughout their service periods. IAT program, one of the most important tasks of DTA, is able to track potential structural crack growth at critical areas in the major airframe structural components of individual aircraft. The F-16C/D aircraft is equipped with a flight data recorder to monitor flight usage and provide the data to support structural load analysis. However, limited memory of flight data recorder allows user to monitor individual aircraft fatigue usage in terms of only the vertical inertia (NzW) data for calculating Crack Severity Index (CSI) value which defines the relative maneuver severity. Current IAT method for the F-16C/D Block 32 based on CSI value calculated from NzW is shown to be not accurate enough to monitor individual aircraft fatigue usage due to several problems. The proposed advanced aircraft service life monitoring method based on flight-by-flight load spectra is recommended as an improved method for the F-16C/D Block 32 aircraft. Flight-by-flight load spectra was generated from downloaded Crash Survival Flight Data Recorder (CSFDR) data by calculating loads for each time hack in selected flight data utilizing loads equations. From the comparison of interpolated fatigue life using CSI value and fatigue test results, it is obvious that proposed advanced IAT method via flight-by-flight load spectra is more reliable and accurate than current IAT method. Therefore, the advanced aircraft service life monitoring method based on flight-by-flight load spectra not only monitors the individual aircraft consumed fatigue life for inspection but also ensures the structural reliability of aging aircrafts throughout their service periods.

[Glycemic, insulinemic index, glycemic load of soy beverage with low and high content of carbohydrates].

PubMed

Torres y Torres, Nimbe; Palacios-González, Berenice; Noriega-López, Lilia; Tovar-Palacio, Armando R

2006-01-01

Consumption of soy has increased in Western countries due to the benefits on health and the attitude of the people to consume natural products as alternative to the use of pharmacological therapies. However, there is no evidence whether the consumption of 25 g of soy protein as recommended by the Food and Drug Administration has some effect on glucose absorption and consequently on insulin secretion. The aim of the present study was to determine glycemic index (GI), insulinemic index (InIn), and glycemic load (GL) of several soy beverages containing low or high concentration of carbohydrates, and compare them with other foods such as peanuts, whole milk, soluble fiber and a mixed meal on GI and InIn. The results showed that soy beverages had low or moderate GI, depending of the presence of other compounds like carbohydrates and fiber. Consumption of soy beverages with low concentration of carbohydrates produced the lowest insulin secretion. Therefore, these products can be recommended in obese and diabetic patients. Finally soy beverages should contain low maltodextrins concentration and be added of soluble fiber.

Impact of simulated three-dimensional perception on precision of depth judgements, technical performance and perceived workload in laparoscopy.

PubMed

Sakata, S; Grove, P M; Hill, A; Watson, M O; Stevenson, A R L

2017-07-01

This study compared precision of depth judgements, technical performance and workload using two-dimensional (2D) and three-dimensional (3D) laparoscopic displays across different viewing distances. It also compared the accuracy of 3D displays with natural viewing, along with the relationship between stereoacuity and 3D laparoscopic performance. A counterbalanced within-subjects design with random assignment to testing sequences was used. The system could display 2D or 3D images with the same set-up. A Howard-Dolman apparatus assessed precision of depth judgements, and three laparoscopic tasks (peg transfer, navigation in space and suturing) assessed performance (time to completion). Participants completed tasks in all combinations of two viewing modes (2D, 3D) and two viewing distances (1 m, 3 m). Other measures administered included the National Aeronautics and Space Administration Task Load Index (perceived workload) and the Randot ® Stereotest (stereoacuity). Depth judgements were 6·2 times as precise at 1 m and 3·0 times as precise at 3 m using 3D versus 2D displays (P < 0·001). Participants performed all laparoscopic tasks faster in 3D at both 1 and 3 m (P < 0.001), with mean completion times up to 64 per cent shorter for 3D versus 2D displays. Workload was lower for 3D displays (up to 34 per cent) than for 2D displays at both viewing distances (P < 0·001). Greater viewing distance inhibited performance for two laparoscopic tasks, and increased perceived workload for all three (P < 0·001). Higher stereoacuity was associated with shorter completion times for the navigating in space task performed in 3D at 1 m (r = - 0·40, P = 0·001). 3D displays offer large improvements over 2D displays in precision of depth judgements, technical performance and perceived workload. © 2017 The Authors. BJS published by John Wiley & Sons Ltd on behalf of BJS Society Ltd.

CLASS Challenging Tasks: Using Cognitive Load Theory to Inform the Design of Challenging Mathematical Tasks

ERIC Educational Resources Information Center

Russo, James; Hopkins, Sarah

2017-01-01

This paper outlines a seven-step process for developing problem-solving tasks informed by cognitive load theory. Through an example of a task developed for Year 2 students, we show how this approach can be used to produce challenging mathematical tasks that aim to optimise cognitive load for each student.

Evaluation of User Interface and Workflow Design of a Bedside Nursing Clinical Decision Support System

PubMed Central

Yuan, Michael Juntao; Finley, George Mike; Mills, Christy; Johnson, Ron Kim

2013-01-01

Background Clinical decision support systems (CDSS) are important tools to improve health care outcomes and reduce preventable medical adverse events. However, the effectiveness and success of CDSS depend on their implementation context and usability in complex health care settings. As a result, usability design and validation, especially in real world clinical settings, are crucial aspects of successful CDSS implementations. Objective Our objective was to develop a novel CDSS to help frontline nurses better manage critical symptom changes in hospitalized patients, hence reducing preventable failure to rescue cases. A robust user interface and implementation strategy that fit into existing workflows was key for the success of the CDSS. Methods Guided by a formal usability evaluation framework, UFuRT (user, function, representation, and task analysis), we developed a high-level specification of the product that captures key usability requirements and is flexible to implement. We interviewed users of the proposed CDSS to identify requirements, listed functions, and operations the system must perform. We then designed visual and workflow representations of the product to perform the operations. The user interface and workflow design were evaluated via heuristic and end user performance evaluation. The heuristic evaluation was done after the first prototype, and its results were incorporated into the product before the end user evaluation was conducted. First, we recruited 4 evaluators with strong domain expertise to study the initial prototype. Heuristic violations were coded and rated for severity. Second, after development of the system, we assembled a panel of nurses, consisting of 3 licensed vocational nurses and 7 registered nurses, to evaluate the user interface and workflow via simulated use cases. We recorded whether each session was successfully completed and its completion time. Each nurse was asked to use the National Aeronautics and Space Administration (NASA) Task Load Index to self-evaluate the amount of cognitive and physical burden associated with using the device. Results A total of 83 heuristic violations were identified in the studies. The distribution of the heuristic violations and their average severity are reported. The nurse evaluators successfully completed all 30 sessions of the performance evaluations. All nurses were able to use the device after a single training session. On average, the nurses took 111 seconds (SD 30 seconds) to complete the simulated task. The NASA Task Load Index results indicated that the work overhead on the nurses was low. In fact, most of the burden measures were consistent with zero. The only potentially significant burden was temporal demand, which was consistent with the primary use case of the tool. Conclusions The evaluation has shown that our design was functional and met the requirements demanded by the nurses’ tight schedules and heavy workloads. The user interface embedded in the tool provided compelling utility to the nurse with minimal distraction. PMID:23612350

Workload assessment of surgeons: correlation between NASA TLX and blinks.

PubMed

Zheng, Bin; Jiang, Xianta; Tien, Geoffrey; Meneghetti, Adam; Panton, O Neely M; Atkins, M Stella

2012-10-01

Blinks are known as an indicator of visual attention and mental stress. In this study, surgeons' mental workload was evaluated utilizing a paper assessment instrument (National Aeronautics and Space Administration Task Load Index, NASA TLX) and by examining their eye blinks. Correlation between these two assessments was reported. Surgeons' eye motions were video-recorded using a head-mounted eye-tracker while the surgeons performed a laparoscopic procedure on a virtual reality trainer. Blink frequency and duration were computed using computer vision technology. The level of workload experienced during the procedure was reported by surgeons using the NASA TLX. A total of 42 valid videos were recorded from 23 surgeons. After blinks were computed, videos were divided into two groups based on the blink frequency: infrequent group (≤ 6 blinks/min) and frequent group (more than 6 blinks/min). Surgical performance (measured by task time and trajectories of tool tips) was not significantly different between these two groups, but NASA TLX scores were significantly different. Surgeons who blinked infrequently reported a higher level of frustration (46 vs. 34, P = 0.047) and higher overall level of workload (57 vs. 47, P = 0.045) than those who blinked more frequently. The correlation coefficients (Pearson test) between NASA TLX and the blink frequency and duration were -0.17 and 0.446. Reduction of blink frequency and shorter blink duration matched the increasing level of mental workload reported by surgeons. The value of using eye-tracking technology for assessment of surgeon mental workload was shown.

The pig as preclinical model for laparoscopic vagus nerve stimulation.

PubMed

Wolthuis, A M; Stakenborg, N; D'Hoore, A; Boeckxstaens, G E

2016-02-01

Cervical vagus nerve stimulation (VNS) prevents manipulation-induced intestinal inflammation and improves intestinal transit in a mouse model of postoperative ileus (POI). Cervical VNS, however, is accompanied by cardiovascular and respiratory side effects. In view of potential clinical application, we therefore evaluated the safety and feasibility of abdominal VNS via laparoscopic approach in a porcine model. Six pigs were used in a non-survival study for both cervical and abdominal VNS. Two cardiac pacing electrodes were positioned around the right cervical and posterior abdominal vagus nerve and connected to an external stimulator. VNS was performed using four different settings (5 and 20 Hz, 0.5 and 1 ms pulse width) during 2 min with ECG recording. Laparoscopic VNS was timed and videotaped, and technical difficulties were noted. A validated National Aeronautics and Space Administration Task Load Index (NASA-TLX) questionnaire was used to evaluate the task and workload. The procedure was completed in all pigs with 4-port laparoscopic technique. Cervical and abdominal VNS were performed after correct identification and isolation of the nerve, and positioning of the electrodes around the nerve. Median laparoscopic operating time was 16 min (range 8-33 min), and median NASA-TLX was 31 (range 11-74). No major complications were encountered. Reduction of heart rate was between 5.5 and 14% for cervical VNS and undetectable for abdominal VNS. In a porcine model, laparoscopic VNS is feasible and safe with cardiac pacing electrodes and may lead to a similar novel approach in humans in the near future.

High post-movement parietal low-beta power during rhythmic tapping facilitates performance in a stop task.

PubMed

Fischer, Petra; Tan, Huiling; Pogosyan, Alek; Brown, Peter

2016-09-01

Voluntary movements are followed by a post-movement electroencephalography (EEG) beta rebound, which increases with practice and confidence in a task. We hypothesized that greater beta modulation reflects less load on cognitive resources and may thus be associated with faster reactions to new stimuli. EEG was recorded in 17 healthy subjects during rhythmically paced index finger tapping. In a STOP condition, participants had to interrupt the upcoming tap in response to an auditory cue, which was timed such that stopping was successful only in ~ 50% of all trials. In a second condition, participants carried on tapping twice after the stop signal (CONTINUE condition). Thus the conditions were distinct in whether abrupt stopping was required as a second task. Modulation of 12-20 Hz power over motor and parietal areas developed with time on each trial and more so in the CONTINUE condition. Reduced modulation in the STOP condition went along with reduced negative mean asynchronies suggesting less confident anticipation of the timing of the next tap. Yet participants were more likely to stop when beta modulation prior to the stop cue was more pronounced. In the STOP condition, expectancy of the stop signal may have increased cognitive load during movement execution given that the task might have to be stopped abruptly. However, within this condition, stopping ability was increased if the preceding tap was followed by a relatively larger beta increase. Significant, albeit weak, correlations confirmed that increased post-movement beta power was associated with faster reactions to new stimuli, consistent with reduced cognitive load. © 2016 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Using ground reaction force to predict knee kinetic asymmetry following anterior cruciate ligament reconstruction.

PubMed

Dai, B; Butler, R J; Garrett, W E; Queen, R M

2014-12-01

Asymmetries in sagittal plane knee kinetics have been identified as a risk factor for anterior cruciate ligament (ACL) re-injury. Clinical tools are needed to identify the asymmetries. This study examined the relationships between knee kinetic asymmetries and ground reaction force (GRF) asymmetries during athletic tasks in adolescent patients following ACL reconstruction (ACL-R). Kinematic and GRF data were collected during a stop-jump task and a side-cutting task for 23 patients. Asymmetry indices between the surgical and non-surgical limbs were calculated for GRF and knee kinetic variables. For the stop-jump task, knee kinetics asymmetry indices were correlated with all GRF asymmetry indices (P < 0.05), except for loading rate. Vertical GRF impulse asymmetry index predicted peak knee moment, average knee moment, and knee work (R(2)  ≥ 0.78, P < 0.01) asymmetry indices. For the side-cutting tasks, knee kinetic asymmetry indices were correlated with the peak propulsion vertical GRF and vertical GRF impulse asymmetry indices (P < 0.05). Vertical GRF impulse asymmetry index predicted peak knee moment, average knee moment, and knee work (R(2)  ≥ 0.55, P < 0.01) asymmetry indices. The vertical GRF asymmetries may be a viable surrogate for knee kinetic asymmetries and therefore may assist in optimizing rehabilitation outcomes and minimizing re-injury rates. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Medication Reconciliation: Work Domain Ontology, prototype development, and a predictive model.

PubMed

Markowitz, Eliz; Bernstam, Elmer V; Herskovic, Jorge; Zhang, Jiajie; Shneiderman, Ben; Plaisant, Catherine; Johnson, Todd R

2011-01-01

Medication errors can result from administration inaccuracies at any point of care and are a major cause for concern. To develop a successful Medication Reconciliation (MR) tool, we believe it necessary to build a Work Domain Ontology (WDO) for the MR process. A WDO defines the explicit, abstract, implementation-independent description of the task by separating the task from work context, application technology, and cognitive architecture. We developed a prototype based upon the WDO and designed to adhere to standard principles of interface design. The prototype was compared to Legacy Health System's and Pre-Admission Medication List Builder MR tools via a Keystroke-Level Model analysis for three MR tasks. The analysis found the prototype requires the fewest mental operations, completes tasks in the fewest steps, and completes tasks in the least amount of time. Accordingly, we believe that developing a MR tool, based upon the WDO and user interface guidelines, improves user efficiency and reduces cognitive load.

Medication Reconciliation: Work Domain Ontology, Prototype Development, and a Predictive Model

PubMed Central

Markowitz, Eliz; Bernstam, Elmer V.; Herskovic, Jorge; Zhang, Jiajie; Shneiderman, Ben; Plaisant, Catherine; Johnson, Todd R.

2011-01-01

Medication errors can result from administration inaccuracies at any point of care and are a major cause for concern. To develop a successful Medication Reconciliation (MR) tool, we believe it necessary to build a Work Domain Ontology (WDO) for the MR process. A WDO defines the explicit, abstract, implementation-independent description of the task by separating the task from work context, application technology, and cognitive architecture. We developed a prototype based upon the WDO and designed to adhere to standard principles of interface design. The prototype was compared to Legacy Health System’s and Pre-Admission Medication List Builder MR tools via a Keystroke-Level Model analysis for three MR tasks. The analysis found the prototype requires the fewest mental operations, completes tasks in the fewest steps, and completes tasks in the least amount of time. Accordingly, we believe that developing a MR tool, based upon the WDO and user interface guidelines, improves user efficiency and reduces cognitive load. PMID:22195146

The influence of time on task on mind wandering and visual working memory.

PubMed

Krimsky, Marissa; Forster, Daniel E; Llabre, Maria M; Jha, Amishi P

2017-12-01

Working memory relies on executive resources for successful task performance, with higher demands necessitating greater resource engagement. In addition to mnemonic demands, prior studies suggest that internal sources of distraction, such as mind wandering (i.e., having off-task thoughts) and greater time on task, may tax executive resources. Herein, the consequences of mnemonic demand, mind wandering, and time on task were investigated during a visual working memory task. Participants (N=143) completed a delayed-recognition visual working memory task, with mnemonic load for visual objects manipulated across trials (1 item=low load; 2 items=high load) and subjective mind wandering assessed intermittently throughout the experiment using a self-report Likert-type scale (1=on-task, 6=off-task). Task performance (correct/incorrect response) and self-reported mind wandering data were evaluated by hierarchical linear modeling to track trial-by-trial fluctuations. Performance declined with greater time on task, and the rate of decline was steeper for high vs low load trials. Self-reported mind wandering increased over time, and significantly varied asa function of both load and time on task. Participants reported greater mind wandering at the beginning of the experiment for low vs. high load trials; however, with greater time on task, more mind wandering was reported during high vs. low load trials. These results suggest that the availability of executive resources in support of working memory maintenance processes fluctuates in a demand-sensitive manner with time on task, and may be commandeered by mind wandering. Copyright © 2017 Elsevier B.V. All rights reserved.

Harnessing the wandering mind: the role of perceptual load.

PubMed

Forster, Sophie; Lavie, Nilli

2009-06-01

Perceptual load is a key determinant of distraction by task-irrelevant stimuli (e.g., Lavie, N. (2005). Distracted and confused?: Selective attention under load. Trends in Cognitive Sciences, 9, 75-82). Here we establish the role of perceptual load in determining an internal form of distraction by task-unrelated thoughts (TUTs or "mind-wandering"). Four experiments demonstrated reduced frequency of TUTs with high compared to low perceptual load in a visual-search task. Alternative accounts in terms of increased demands on responses, verbal working memory or motivation were ruled out and clear effects of load were found for unintentional TUTs. Individual differences in load effects on internal (TUTs) and external (response-competition) distractors were correlated. These results suggest that exhausting attentional capacity in task-relevant processing under high perceptual load can reduce processing of task-irrelevant information from external and internal sources alike.

Enhancement and suppression in the visual field under perceptual load.

PubMed

Parks, Nathan A; Beck, Diane M; Kramer, Arthur F

2013-01-01

The perceptual load theory of attention proposes that the degree to which visual distractors are processed is a function of the attentional demands of a task-greater demands increase filtering of irrelevant distractors. The spatial configuration of such filtering is unknown. Here, we used steady-state visual evoked potentials (SSVEPs) in conjunction with time-domain event-related potentials (ERPs) to investigate the distribution of load-induced distractor suppression and task-relevant enhancement in the visual field. Electroencephalogram (EEG) was recorded while subjects performed a foveal go/no-go task that varied in perceptual load. Load-dependent distractor suppression was assessed by presenting a contrast reversing ring at one of three eccentricities (2, 6, or 11°) during performance of the go/no-go task. Rings contrast reversed at 8.3 Hz, allowing load-dependent changes in distractor processing to be tracked in the frequency-domain. ERPs were calculated to the onset of stimuli in the load task to examine load-dependent modulation of task-relevant processing. Results showed that the amplitude of the distractor SSVEP (8.3 Hz) was attenuated under high perceptual load (relative to low load) at the most proximal (2°) eccentricity but not at more eccentric locations (6 or 11°). Task-relevant ERPs revealed a significant increase in N1 amplitude under high load. These results are consistent with a center-surround configuration of load-induced enhancement and suppression in the visual field.

[Effects of mental workload on work ability in primary and secondary school teachers].

PubMed

Xiao, Yuanmei; Li, Weijuan; Ren, Qingfeng; Ren, Xiaohui; Wang, Zhiming; Wang, Mianzhen; Lan, Yajia

2015-02-01

To investigate the change pattern of primary and secondary school teachers' work ability with the changes in their mental workload. A total of 901 primary and secondary school teachers were selected by random cluster sampling, and then their mental workload and work ability were assessed by National Aeronautics and Space Administration-Task Load Index (NASA-TLX) and Work Ability Index (WAI) questionnaires, whose reliability and validity had been tested. The effects of their mental workload on the work ability were analyzed. Primary and secondary school teachers' work ability reached the highest level at a certain level of mental workload (55.73< mental workload ≤ 64.10). When their mental workload was lower than the level, their work ability had a positive correlation with the mental workload. Their work ability increased or maintained stable with the increasing mental workload. Moreover, the percentage of teachers with good work ability increased, while that of teachers with moderate work ability decreased. But when their mental workload was higher than the level, their work ability had a negative correlation with the mental workload. Their work ability significantly decreased with the increasing mental workload (P < 0.01). Furthermore, the percentage of teachers with good work ability decreased, while that of teachers with moderate work ability increased (P < 0.001). Too high or low mental workload will result in the decline of primary and secondary school teachers' work ability. Moderate mental workload (55.73∼64.10) will benefit the maintaining and stabilization of their work ability.

Theory of Mind and Empathy in Children With ADHD.

PubMed

Maoz, Hagai; Gvirts, Hila Z; Sheffer, Maya; Bloch, Yuval

2017-05-01

The current study compared empathy and theory of mind (ToM) between children with ADHD and healthy controls, and assessed changes in ToM among children with ADHD following administration of methylphenidate (MPH). Twenty-four children with ADHD (mean age = 10.3 years) were compared with 36 healthy controls. All children completed the interpersonal reactivity index (IRI), a self-reported empathy questionnaire, and performed the "faux-pas" recognition task (FPR). Children with ADHD performed the task with and without MPH. Children with ADHD showed significantly lower levels of self-reported empathy on most IRI subscales. FPR scores were significantly lower in children with ADHD and were improved, following the administration of MPH, to a level equal to that found in healthy controls. Children with ADHD show impaired self-reported empathy and FPR when compared with healthy controls. Stimulants improve FPR in children with ADHD to a level equal to that in healthy controls.

Quantitative assessment of workload and stressors in clinical radiation oncology.

PubMed

Mazur, Lukasz M; Mosaly, Prithima R; Jackson, Marianne; Chang, Sha X; Burkhardt, Katharin Deschesne; Adams, Robert D; Jones, Ellen L; Hoyle, Lesley; Xu, Jing; Rockwell, John; Marks, Lawrence B

2012-08-01

Workload level and sources of stressors have been implicated as sources of error in multiple settings. We assessed workload levels and sources of stressors among radiation oncology professionals. Furthermore, we explored the potential association between workload and the frequency of reported radiotherapy incidents by the World Health Organization (WHO). Data collection was aimed at various tasks performed by 21 study participants from different radiation oncology professional subgroups (simulation therapists, radiation therapists, physicists, dosimetrists, and physicians). Workload was assessed using National Aeronautics and Space Administration Task-Load Index (NASA TLX). Sources of stressors were quantified using observational methods and segregated using a standard taxonomy. Comparisons between professional subgroups and tasks were made using analysis of variance ANOVA, multivariate ANOVA, and Duncan test. An association between workload levels (NASA TLX) and the frequency of radiotherapy incidents (WHO incidents) was explored (Pearson correlation test). A total of 173 workload assessments were obtained. Overall, simulation therapists had relatively low workloads (NASA TLX range, 30-36), and physicists had relatively high workloads (NASA TLX range, 51-63). NASA TLX scores for physicians, radiation therapists, and dosimetrists ranged from 40-52. There was marked intertask/professional subgroup variation (P<.0001). Mental demand (P<.001), physical demand (P=.001), and effort (P=.006) significantly differed among professional subgroups. Typically, there were 3-5 stressors per cycle of analyzed tasks with the following distribution: interruptions (41.4%), time factors (17%), technical factors (13.6%), teamwork issues (11.6%), patient factors (9.0%), and environmental factors (7.4%). A positive association between workload and frequency of reported radiotherapy incidents by the WHO was found (r = 0.87, P value=.045). Workload level and sources of stressors vary among professional subgroups. Understanding the factors that influence these findings can guide adjustments to the workflow procedures, physical layout, and/or communication protocols to enhance safety. Additional evaluations are needed in order to better understand if these findings are systemic. Copyright © 2012 Elsevier Inc. All rights reserved.

Baseline Intraocular Pressure Is Associated With Subjective Sensitivity to Physical Exertion in Young Males.

PubMed

Vera, Jesús; Jiménez, Raimundo; García, José Antonio; Perales, José Cesar; Cárdenas, David

2018-03-01

The purposes of this study were to (a) investigate the effect of physical effort (cycling for 60 min at 60 ± 5% of individually computed reserve heart-rate capacity), combined with 2 different levels of cognitive demand (2-back, oddball), on intraocular pressure (IOP) and subjective judgments of perceived exertion (ratings of perceived exertion [RPE]), affect (Affective Valence subscale of the Self-Assessment Manikin [SAM]), and mental workload (National Aeronautics and Space Administration Task Load Index [NASA-TLX]); and (b) ascertain whether baseline IOP, measured before exercise, is associated with individual differences in subjective assessments of effort and affective response during exercise. Seventeen participants (M age = 23.28 ± 2.37 years) performed 2 physical/cognitive dual tasks, matched in physical demand but with different mental requirements (2-back, oddball). We assessed IOP before exercise, after 2 min of active recovery, and after 15 min of passive recovery, and we also collected RPE and SAM measures during the sessions (28 measurement points). We used NASA-TLX and cognitive performance as checks of the mental manipulation. (a) Intraocular pressure increased after concomitant physical/mental effort, with the effect reaching statistical significance after the 2-back task (p = .002, d = 0.35) but not after the oddball condition (p = .092, d = 0.29). (b) Baseline IOP was associated with subjective sensitivity to effort and showed statistical significance for the oddball condition (p = .03, ƞ p 2  = .622) but not for the 2-back task (F < 1). Results suggest a relationship between IOP and physical/cognitive effort, which could have implications for the management of glaucoma. Additionally, a rapid measure of IOP could be used as a marker of individual effort sensitivity in applied settings.

Quantitative Assessment of Workload and Stressors in Clinical Radiation Oncology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazur, Lukasz M., E-mail: lukasz_mazur@ncsu.edu; Industrial Extension Service, North Carolina State University, Raleigh, North Carolina; Biomedical Engineering, North Carolina State University, Raleigh, North Carolina

2012-08-01

Purpose: Workload level and sources of stressors have been implicated as sources of error in multiple settings. We assessed workload levels and sources of stressors among radiation oncology professionals. Furthermore, we explored the potential association between workload and the frequency of reported radiotherapy incidents by the World Health Organization (WHO). Methods and Materials: Data collection was aimed at various tasks performed by 21 study participants from different radiation oncology professional subgroups (simulation therapists, radiation therapists, physicists, dosimetrists, and physicians). Workload was assessed using National Aeronautics and Space Administration Task-Load Index (NASA TLX). Sources of stressors were quantified using observational methodsmore » and segregated using a standard taxonomy. Comparisons between professional subgroups and tasks were made using analysis of variance ANOVA, multivariate ANOVA, and Duncan test. An association between workload levels (NASA TLX) and the frequency of radiotherapy incidents (WHO incidents) was explored (Pearson correlation test). Results: A total of 173 workload assessments were obtained. Overall, simulation therapists had relatively low workloads (NASA TLX range, 30-36), and physicists had relatively high workloads (NASA TLX range, 51-63). NASA TLX scores for physicians, radiation therapists, and dosimetrists ranged from 40-52. There was marked intertask/professional subgroup variation (P<.0001). Mental demand (P<.001), physical demand (P=.001), and effort (P=.006) significantly differed among professional subgroups. Typically, there were 3-5 stressors per cycle of analyzed tasks with the following distribution: interruptions (41.4%), time factors (17%), technical factors (13.6%), teamwork issues (11.6%), patient factors (9.0%), and environmental factors (7.4%). A positive association between workload and frequency of reported radiotherapy incidents by the WHO was found (r = 0.87, P value=.045). Conclusions: Workload level and sources of stressors vary among professional subgroups. Understanding the factors that influence these findings can guide adjustments to the workflow procedures, physical layout, and/or communication protocols to enhance safety. Additional evaluations are needed in order to better understand if these findings are systemic.« less

Effects of Memory Load and Test Position on Short-Duration Sustained Attention Tasks.

PubMed

Laurie-Rose, Cynthia; Frey, Meredith C; Sibata, Erick; Zamary, Amanda

2015-01-01

The current study applies a dual-task working memory and vigilance task to examine sustained attention performance and perceived workload in a multi-instrument battery. In Experiment 1 we modified a task developed by Helton and Russell (2011) to examine declines in performance and to assess the effects of its position within a larger battery. Experiment 1 failed to reveal a sensitivity decrement, and test position revealed only spurious influence. Workload scores derived from the NASA-TLX fell at the high end of the scale, with mental and temporal demand receiving the highest ratings. In Experiment 2, we modified the dual task to place more emphasis on attention rather than working memory. Results revealed a significant decline in performance across the vigil for the perceptual sensitivity index A'. Test position (early vs. late) effects appeared with the reaction time variability measure, with performance becoming more variable when the task appeared in the latter half of the battery. Workload scores varied according to position in the battery: Workload scores were higher when the vigilance task appeared in the latter half of the battery. Practical and theoretical implications are discussed.

Visual short-term memory load strengthens selective attention.

PubMed

Roper, Zachary J J; Vecera, Shaun P

2014-04-01

Perceptual load theory accounts for many attentional phenomena; however, its mechanism remains elusive because it invokes underspecified attentional resources. Recent dual-task evidence has revealed that a concurrent visual short-term memory (VSTM) load slows visual search and reduces contrast sensitivity, but it is unknown whether a VSTM load also constricts attention in a canonical perceptual load task. If attentional selection draws upon VSTM resources, then distraction effects-which measure attentional "spill-over"-will be reduced as competition for resources increases. Observers performed a low perceptual load flanker task during the delay period of a VSTM change detection task. We observed a reduction of the flanker effect in the perceptual load task as a function of increasing concurrent VSTM load. These findings were not due to perceptual-level interactions between the physical displays of the two tasks. Our findings suggest that perceptual representations of distractor stimuli compete with the maintenance of visual representations held in memory. We conclude that access to VSTM determines the degree of attentional selectivity; when VSTM is not completely taxed, it is more likely for task-irrelevant items to be consolidated and, consequently, affect responses. The "resources" hypothesized by load theory are at least partly mnemonic in nature, due to the strong correspondence they share with VSTM capacity.

Body mass index predicts selected physical fitness attributes but is not associated with performance on military relevant tasks in U.S. Army Soldiers.

PubMed

Pierce, Joseph R; DeGroot, David W; Grier, Tyson L; Hauret, Keith G; Nindl, Bradley C; East, Whitfield B; McGurk, Michael S; Jones, Bruce H

2017-11-01

Army body composition standards are based upon validated criteria; however, certain field-expedient methodologies (e.g., weight-for-height, body mass index [BMI]) may disqualify individuals from service who may otherwise excel on physical performance and military-relevant tasks. The purpose was to assess soldier physical performance and military-specific task/fitness performance stratified by BMI. Cross-sectional observational study. Male (n=275) and female (n=46) soldiers performed a wide-array of physical fitness tests and military-specific tasks, including the Army physical fitness test (APFT). Within-sex performance data were analyzed by BMI tertile stratification or by Army Body Composition Program (ABCP) weight-for-height (calculated BMI) screening standards using ANOVA/Tukey post-hoc or independent t-tests, respectively. BMI stratification (higher vs. lower BMI) was associated with significant improvements in muscular strength and power, but also with decrements in speed/agility in male and female soldiers. Within the military specific tasks, a higher BMI was associated with an increased APFT 2-Mile Run time; however, performance on a 1600-m Loaded March or a Warrior Task and Battle Drill obstacle course was not related to BMI in either sex. Male and Female soldiers who did not meet ABCP screening standards demonstrated a slower 2-Mile Run time; however, not meeting the ABCP BMI standard only affected a minimal number (∼6%) of soldiers' ability to pass the APFT. Military body composition standards require a careful balance between physical performance, health, and military readiness. Allowances should be considered where tradeoffs exist between body composition classifications and performance on physical tasks with high military relevance. Published by Elsevier Ltd.

Acute physical exercise affected processing efficiency in an auditory attention task more than processing effectiveness.

PubMed

Dutke, Stephan; Jaitner, Thomas; Berse, Timo; Barenberg, Jonathan

2014-02-01

Research on effects of acute physical exercise on performance in a concurrent cognitive task has generated equivocal evidence. Processing efficiency theory predicts that concurrent physical exercise can increase resource requirements for sustaining cognitive performance even when the level of performance is unaffected. This hypothesis was tested in a dual-task experiment. Sixty young adults worked on a primary auditory attention task and a secondary interval production task while cycling on a bicycle ergometer. Physical load (cycling) and cognitive load of the primary task were manipulated. Neither physical nor cognitive load affected primary task performance, but both factors interacted on secondary task performance. Sustaining primary task performance under increased physical and/or cognitive load increased resource consumption as indicated by decreased secondary task performance. Results demonstrated that physical exercise effects on cognition might be underestimated when only single task performance is the focus.

Contingent capture of visual-spatial attention depends on capacity-limited central mechanisms: evidence from human electrophysiology and the psychological refractory period.

PubMed

Brisson, Benoit; Leblanc, Emilie; Jolicoeur, Pierre

2009-02-01

It has recently been demonstrated that a lateralized distractor that matches the individual's top-down control settings elicits an N2pc wave, an electrophysiological index of the focus of visual-spatial attention, indicating that contingent capture has a visual-spatial locus. Here, we investigated whether contingent capture required capacity-limited central resources by incorporating a contingent capture task as the second task of a psychological refractory period (PRP) dual-task paradigm. The N2pc was used to monitor where observers were attending while they performed concurrent central processing known to cause the PRP effect. The N2pc elicited by the lateralized distractor that matched the top-down control settings was attenuated in high concurrent central load conditions, indicating that although involuntary, the deployment of visual-spatial attention occurring during contingent capture depends on capacity-limited central resources.

Cognitive Load Theory: An Empirical Study of Anxiety and Task Performance in Language Learning

ERIC Educational Resources Information Center

Chen, I-Jung; Chang, Chi-Cheng

2009-01-01

Introduction: This study explores the relationship among three variables--cognitive load, foreign language anxiety, and task performance. Cognitive load refers to the load imposed on working memory while performing a particular task. The authors hypothesized that anxiety consumes the resources of working memory, leaving less capacity for cognitive…

Assessment of mental workload and academic motivation in medical students.

PubMed

Atalay, Kumru Didem; Can, Gulin Feryal; Erdem, Saban Remzi; Muderrisoglu, Ibrahim Haldun

2016-05-01

To investigate the level of correlation and direction of linearity between academic motivation and subjective workload. The study was conducted at Baskent University School of Medicine, Ankara, Turkey, from December 2013 to February 2014, and comprised Phase 5 Phase 6 medical students. Subjective workload level was determined by using National Aeronautics and Space Administration Task Load Index scale that was adapted to Turkish. Academic motivation values were obtained with the help of Academic Motivation Scale university form. SPSS 17 was used for statistical analysis. Of the total 105 subjects, 65(62%) students were in Phase 5 and 40(38%) were in Phase 6. Of the Phase 5 students, 18(27.7%) were boys and 47(72.3%) were girls, while of the Phase 6 students, 16(40%) were boys and 24(60%) were girls. There were significant differences in Phase 5 and Phase 6 students for mental effort (p=0.00) and physical effort (p=0.00). The highest correlation in Phase 5 was between mental effort and intrinsic motivation (r=0.343). For Phase 6, highest correlation was between effort and amotivation (r= -0.375). Subjective workload affected academic motivation in medical students.

Construct and face validity of the American College of Surgeons/Association of Program Directors in Surgery laparoscopic troubleshooting team training exercise.

PubMed

Arain, Nabeel A; Hogg, Deborah C; Gala, Rajiv B; Bhoja, Ravi; Tesfay, Seifu T; Webb, Erin M; Scott, Daniel J

2012-01-01

Our aim was to develop an objective scoring system and evaluate construct and face validity for a laparoscopic troubleshooting team training exercise. Surgery and gynecology novices (n = 14) and experts (n = 10) participated. Assessments included the following: time-out, scenario decision making (SDM) score (based on essential treatments rendered and completion time), operating room communication assessment (investigator developed), line operations safety audits (teamwork), and National Aeronautics and Space Administration-Task Load Index (workload). Significant differences were detected for SDM scores for scenarios 1 (192 vs 278; P = .01) and 3 (129 vs 225; P = .004), operating room communication assessment (67 vs 91; P = .002), and line operations safety audits (58 vs 87; P = .001), but not for time-out (46 vs 51) or scenario 2 SDM score (301 vs 322). Workload was similar for both groups and face validity (8.8 on a 10-point scale) was strongly supported. Objective decision-making scoring for 2 of 3 scenarios and communication and teamwork ratings showed construct validity. Face validity and participant feedback were excellent. Copyright © 2012 Elsevier Inc. All rights reserved.

Object-Based Attention Overrides Perceptual Load to Modulate Visual Distraction

ERIC Educational Resources Information Center

Cosman, Joshua D.; Vecera, Shaun P.

2012-01-01

The ability to ignore task-irrelevant information and overcome distraction is central to our ability to efficiently carry out a number of tasks. One factor shown to strongly influence distraction is the perceptual load of the task being performed; as the perceptual load of task-relevant information processing increases, the likelihood that…

Effects of cues in a binary categorization task on dual-task performance, mental workload, and effort.

PubMed

Botzer, Assaf; Meyer, Joachim; Parmet, Yisrael

2016-09-01

Binary cues help operators perform binary categorization tasks, such as monitoring for system failures. They may also allow them to attend to other tasks they concurrently perform. If the time saved by using cues is allocated to other concurrent tasks, users' overall effort may remain unchanged. In 2 experiments, participants performed a simulated quality control task, together with a tracking task. In half the experimental blocks cues were available, and participants could use them in their decisions about the quality of products (intact or faulty). In Experiment 1, the difficulty of tracking was constant, while in Experiment 2, tracking difficulty differed in the 2 halves of the experiment. In both experiments, participants reported on the NASA Task Load Index that cues improved their performance and reduced their frustration. Consequently, their overall score on mental workload (MWL) was lower with cues. They also reported, however, that cues did not reduce their effort. We conclude that cues and other forms of automation may support task performance and reduce overall MWL, but this will not necessarily mean that users will work less hard. Thus, effort and overall MWL should be evaluated separately, if one wants to obtain a full picture of the effects of automation. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Development and validation of a surgical workload measure: the surgery task load index (SURG-TLX).

PubMed

Wilson, Mark R; Poolton, Jamie M; Malhotra, Neha; Ngo, Karen; Bright, Elizabeth; Masters, Rich S W

2011-09-01

The purpose of the present study was to develop and validate a multidimensional, surgery-specific workload measure (the SURG-TLX), and to determine its utility in providing diagnostic information about the impact of various sources of stress on the perceived demands of trained surgical operators. As a wide range of stressors have been identified for surgeons in the operating room, the current approach of considering stress as a unidimensional construct may not only limit the degree to which underlying mechanisms may be understood but also the degree to which training interventions may be successfully matched to particular sources of stress. The dimensions of the SURG-TLX were based on two current multidimensional workload measures and developed via focus group discussion. The six dimensions were defined as mental demands, physical demands, temporal demands, task complexity, situational stress, and distractions. Thirty novices were trained on the Fundamentals of Laparoscopic Surgery (FLS) peg transfer task and then completed the task under various conditions designed to manipulate the degree and source of stress experienced: task novelty, physical fatigue, time pressure, evaluation apprehension, multitasking, and distraction. The results were supportive of the discriminant sensitivity of the SURG-TLX to different sources of stress. The sub-factors loaded on the relevant stressors as hypothesized, although the evaluation pressure manipulation was not strong enough to cause a significant rise in situational stress. The present study provides support for the validity of the SURG-TLX instrument and also highlights the importance of considering how different stressors may load surgeons. Implications for categorizing the difficulty of certain procedures, the implementation of new technology in the operating room (man-machine interface issues), and the targeting of stress training strategies to the sources of demand are discussed. Modifications to the scale to enhance clinical utility are also suggested.

Effects of noise and task loading on a communication task loading on a communication task

NASA Astrophysics Data System (ADS)

Orrell, Dean H., II

Previous research had shown the effect of noise on a single communication task. This research has been criticized as not being representative of a real world situation since subjects allocated all of their attention to only one task. In the present study, the effect of adding a loading task to a standard noise-communication paradigm was investigated. Subjects performed both a communication task (Modified Rhyme Test; House et al. 1965) and a short term memory task (Sternberg, 1969) in simulated levels of aircraft noise (95, 105 and 115 dB overall sound pressure level (OASPL)). Task loading was varied with Sternberg's task by requiring subjects to memorize one, four, or six alphanumeric characters. Simulated aircraft noise was varied between levels of 95, 105 and 115 dB OASPL using a pink noise source. Results show that the addition of Sternberg's task and little effect on the intelligibility of the communication task while response time for the communication task increased.

A colored petri nets based workload evaluation model and its validation through Multi-Attribute Task Battery-II.

PubMed

Wang, Peng; Fang, Weining; Guo, Beiyuan

2017-04-01

This paper proposed a colored petri nets based workload evaluation model. A formal interpretation of workload was firstly introduced based on the process that reflection of petri nets components to task. A petri net based description of Multiple Resources theory was given by comprehending it from a new angle. A new application of VACP rating scales named V/A-C-P unit, and the definition of colored transitions were proposed to build a model of task process. The calculation of workload mainly has the following four steps: determine token's initial position and values; calculate the weight of directed arcs on the basis of the rules proposed; calculate workload from different transitions, and correct the influence of repetitive behaviors. Verify experiments were carried out based on Multi-Attribute Task Battery-II software. Our results show that there is a strong correlation between the model values and NASA -Task Load Index scores (r=0.9513). In addition, this method can also distinguish behavior characteristics between different people. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluative pressure overcomes perceptual load effects.

PubMed

Normand, Alice; Autin, Frédérique; Croizet, Jean-Claude

2015-06-01

Perceptual load has been found to be a powerful bottom-up determinant of distractibility, with high perceptual load preventing distraction by any irrelevant information. However, when under evaluative pressure, individuals exert top-down attentional control by giving greater weight to task-relevant features, making them more distractible from task-relevant distractors. One study tested whether the top-down modulation of attention under evaluative pressure overcomes the beneficial bottom-up effect of high perceptual load on distraction. Using a response-competition task, we replicated previous findings that high levels of perceptual load suppress task-relevant distractor response interference, but only for participants in a control condition. Participants under evaluative pressure (i.e., who believed their intelligence was assessed) showed interference from task-relevant distractor at all levels of perceptual load. This research challenges the assumptions of the perceptual load theory and sheds light on a neglected determinant of distractibility: the self-relevance of the performance situation in which attentional control is solicited.

Components of working memory and visual selective attention.

PubMed

Burnham, Bryan R; Sabia, Matthew; Langan, Catherine

2014-02-01

Load theory (Lavie, N., Hirst, A., De Fockert, J. W., & Viding, E. [2004]. Load theory of selective attention and cognitive control. Journal of Experimental Psychology: General, 133, 339-354.) proposes that control of attention depends on the amount and type of load that is imposed by current processing. Specifically, perceptual load should lead to efficient distractor rejection, whereas working memory load (dual-task coordination) should hinder distractor rejection. Studies support load theory's prediction that working memory load will lead to larger distractor effects; however, these studies used secondary tasks that required only verbal working memory and the central executive. The present study examined which other working memory components (visual, spatial, and phonological) influence visual selective attention. Subjects completed an attentional capture task alone (single-task) or while engaged in a working memory task (dual-task). Results showed that along with the central executive, visual and spatial working memory influenced selective attention, but phonological working memory did not. Specifically, attentional capture was larger when visual or spatial working memory was loaded, but phonological working memory load did not affect attentional capture. The results are consistent with load theory and suggest specific components of working memory influence visual selective attention. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Selective attention to task-irrelevant emotional distractors is unaffected by the perceptual load associated with a foreground task.

PubMed

Hindi Attar, Catherine; Müller, Matthias M

2012-01-01

A number of studies have shown that emotionally arousing stimuli are preferentially processed in the human brain. Whether or not this preference persists under increased perceptual load associated with a task at hand remains an open question. Here we manipulated two possible determinants of the attentional selection process, perceptual load associated with a foreground task and the emotional valence of concurrently presented task-irrelevant distractors. As a direct measure of sustained attentional resource allocation in early visual cortex we used steady-state visual evoked potentials (SSVEPs) elicited by distinct flicker frequencies of task and distractor stimuli. Subjects either performed a detection (low load) or discrimination (high load) task at a centrally presented symbol stream that flickered at 8.6 Hz while task-irrelevant neutral or unpleasant pictures from the International Affective Picture System (IAPS) flickered at a frequency of 12 Hz in the background of the stream. As reflected in target detection rates and SSVEP amplitudes to both task and distractor stimuli, unpleasant relative to neutral background pictures more strongly withdrew processing resources from the foreground task. Importantly, this finding was unaffected by the factor 'load' which turned out to be a weak modulator of attentional processing in human visual cortex.

The effect of perceptual load on tactile spatial attention: Evidence from event-related potentials.

PubMed

Gherri, Elena; Berreby, Fiona

2017-10-15

To investigate whether tactile spatial attention is modulated by perceptual load, behavioural and electrophysiological measures were recorded during two spatial cuing tasks in which the difficulty of the target/non-target discrimination was varied (High and Low load tasks). Moreover, to study whether attentional modulations by load are sensitive to the availability of visual information, the High and Low load tasks were carried out under both illuminated and darkness conditions. ERPs to cued and uncued non-targets were compared as a function of task (High vs. Low load) and illumination condition (Light vs. Darkness). Results revealed that the locus of tactile spatial attention was determined by a complex interaction between perceptual load and illumination conditions during sensory-specific stages of processing. In the Darkness, earlier effects of attention were present in the High load than in the Low load task, while no difference between tasks emerged in the Light. By contrast, increased load was associated with stronger attention effects during later post-perceptual processing stages regardless of illumination conditions. These findings demonstrate that ERP correlates of tactile spatial attention are strongly affected by the perceptual load of the target/non-target discrimination. However, differences between illumination conditions show that the impact of load on tactile attention depends on the presence of visual information. Perceptual load is one of the many factors that contribute to determine the effects of spatial selectivity in touch. Copyright © 2017 Elsevier B.V. All rights reserved.

Upper limb load as a function of repetitive task parameters: part 1--a model of upper limb load.

PubMed

Roman-Liu, Danuta

2005-01-01

The aim of the study was to develop a theoretical indicator of upper limb musculoskeletal load based on repetitive task parameters. As such the dimensionless parameter, Integrated Cycle Load (ICL) was accepted. It expresses upper limb load which occurs during 1 cycle. The indicator is based on a model of a repetitive task, which consists of a model of the upper limb, a model of basic types of upper limb forces and a model of parameters of a repetitive task such as length of the cycle, length of periods of the cycle and external force exerted during each of the periods of the cycle. Calculations of the ICL parameter were performed for 12 different variants of external load characterised by different values of repetitive task parameters. A comparison of ICL, which expresses external load with a physiological indicator of upper limb load, is presented in Part 2 of the paper.

Transethosomal gels as carriers for the transdermal delivery of colchicine: statistical optimization, characterization, and ex vivo evaluation

PubMed Central

Abdulbaqi, Ibrahim M; Darwis, Yusrida; Assi, Reem Abou; Khan, Nurzalina Abdul Karim

2018-01-01

Introduction Colchicine is used for the treatment of gout, pseudo-gout, familial Mediterranean fever, and many other illnesses. Its oral administration is associated with poor bioavailability and severe gastrointestinal side effects. The drug is also known to have a low therapeutic index. Thus to overcome these drawbacks, the transdermal delivery of colchicine was investigated using transethosomal gels as potential carriers. Methods Colchicine-loaded transethosomes (TEs) were prepared by the cold method and statistically optimized using three sets of 24 factorial design experiments. The optimized formulations were incorporated into Carbopol 940® gel base. The prepared colchicine-loaded transethosomal gels were further characterized for vesicular size, dispersity, zeta potential, drug content, pH, viscosity, yield, rheological behavior, and ex vivo skin permeation through Sprague Dawley rats’ back skin. Results The results showed that the colchicine-loaded TEs had aspherical irregular shape, nanometric size range, and high entrapment efficiency. All the formulated gels exhibited non-Newtonian plastic flow without thixotropy. Colchicine-loaded transethosomal gels were able to significantly enhance the skin permeation parameters of the drug in comparison to the non-ethosomal gel. Conclusion These findings suggested that the transethosomal gels are promising carriers for the transdermal delivery of colchicine, providing an alternative route for drug administration. PMID:29670336

Transethosomal gels as carriers for the transdermal delivery of colchicine: statistical optimization, characterization, and ex vivo evaluation.

PubMed

Abdulbaqi, Ibrahim M; Darwis, Yusrida; Assi, Reem Abou; Khan, Nurzalina Abdul Karim

2018-01-01

Colchicine is used for the treatment of gout, pseudo-gout, familial Mediterranean fever, and many other illnesses. Its oral administration is associated with poor bioavailability and severe gastrointestinal side effects. The drug is also known to have a low therapeutic index. Thus to overcome these drawbacks, the transdermal delivery of colchicine was investigated using transethosomal gels as potential carriers. Colchicine-loaded transethosomes (TEs) were prepared by the cold method and statistically optimized using three sets of 24 factorial design experiments. The optimized formulations were incorporated into Carbopol 940 ® gel base. The prepared colchicine-loaded transethosomal gels were further characterized for vesicular size, dispersity, zeta potential, drug content, pH, viscosity, yield, rheological behavior, and ex vivo skin permeation through Sprague Dawley rats' back skin. The results showed that the colchicine-loaded TEs had aspherical irregular shape, nanometric size range, and high entrapment efficiency. All the formulated gels exhibited non-Newtonian plastic flow without thixotropy. Colchicine-loaded transethosomal gels were able to significantly enhance the skin permeation parameters of the drug in comparison to the non-ethosomal gel. These findings suggested that the transethosomal gels are promising carriers for the transdermal delivery of colchicine, providing an alternative route for drug administration.

An investigation of pupil-based cognitive load measurement with low cost infrared webcam under light reflex interference.

PubMed

Chen, Siyuan; Epps, Julien; Chen, Fang

2013-01-01

Using the task-evoked pupillary response (TEPR) to index cognitive load can contribute significantly to the assessment of memory function and cognitive skills in patients. However, the measurement of pupillary response is currently limited to a well-controlled lab environment due to light reflex and also relies heavily on expensive video-based eye trackers. Furthermore, commercial eye trackers are usually dedicated to gaze direction measurement, and their calibration procedure and computing resource are largely redundant for pupil-based cognitive load measurement (PCLM). In this study, we investigate the validity of cognitive load measurement with (i) pupil light reflex in a less controlled luminance background; (ii) a low-cost infrared (IR) webcam for the TEPR in a controlled luminance background. ANOVA results show that with an appropriate baseline selection and subtraction, the light reflex is significantly reduced, suggesting the possibility of less constrained practical applications of PCLM. Compared with the TEPR from a commercial remote eye tracker, a low-cost IR webcam achieved a similar TEPR pattern and no significant difference was found between the two devices in terms of cognitive load measurement across five induced load levels.

Respiratory Changes in Response to Cognitive Load: A Systematic Review.

PubMed

Grassmann, Mariel; Vlemincx, Elke; von Leupoldt, Andreas; Mittelstädt, Justin M; Van den Bergh, Omer

2016-01-01

When people focus attention or carry out a demanding task, their breathing changes. But which parameters of respiration vary exactly and can respiration reliably be used as an index of cognitive load? These questions are addressed in the present systematic review of empirical studies investigating respiratory behavior in response to cognitive load. Most reviewed studies were restricted to time and volume parameters while less established, yet meaningful parameters such as respiratory variability have rarely been investigated. The available results show that respiratory behavior generally reflects cognitive processing and that distinct parameters differ in sensitivity: While mentally demanding episodes are clearly marked by faster breathing and higher minute ventilation, respiratory amplitude appears to remain rather stable. The present findings further indicate that total variability in respiratory rate is not systematically affected by cognitive load whereas the correlated fraction decreases. In addition, we found that cognitive load may lead to overbreathing as indicated by decreased end-tidal CO2 but is also accompanied by elevated oxygen consumption and CO2 release. However, additional research is needed to validate the findings on respiratory variability and gas exchange measures. We conclude by outlining recommendations for future research to increase the current understanding of respiration under cognitive load.

Respiratory Changes in Response to Cognitive Load: A Systematic Review

PubMed Central

Grassmann, Mariel; Vlemincx, Elke; von Leupoldt, Andreas; Mittelstädt, Justin M.

2016-01-01

When people focus attention or carry out a demanding task, their breathing changes. But which parameters of respiration vary exactly and can respiration reliably be used as an index of cognitive load? These questions are addressed in the present systematic review of empirical studies investigating respiratory behavior in response to cognitive load. Most reviewed studies were restricted to time and volume parameters while less established, yet meaningful parameters such as respiratory variability have rarely been investigated. The available results show that respiratory behavior generally reflects cognitive processing and that distinct parameters differ in sensitivity: While mentally demanding episodes are clearly marked by faster breathing and higher minute ventilation, respiratory amplitude appears to remain rather stable. The present findings further indicate that total variability in respiratory rate is not systematically affected by cognitive load whereas the correlated fraction decreases. In addition, we found that cognitive load may lead to overbreathing as indicated by decreased end-tidal CO2 but is also accompanied by elevated oxygen consumption and CO2 release. However, additional research is needed to validate the findings on respiratory variability and gas exchange measures. We conclude by outlining recommendations for future research to increase the current understanding of respiration under cognitive load. PMID:27403347

The NASA Task Load Index as a measure of overall workload among neonatal, paediatric and adult intensive care nurses.

PubMed

Tubbs-Cooley, Heather L; Mara, Constance A; Carle, Adam C; Gurses, Ayse P

2018-02-12

The NASA Task Load Index (NASA-TLX) is a subjective workload assessment scale developed for use in aviation and increasingly applied to healthcare. The scale purports to measure overall workload as a single variable calculated by summing responses to six items. Since no data address the validity of this scoring approach in health care, we evaluated the single factor structure of the NASA-TLX as a measure of overall workload among intenisive care nurses. Confirmatory factor analysis of data from two studies of nurse workload in neonatal, paediatric, and adult intensive care units. Study 1 data were obtained from 136 nurses in one neonatal intensive care unit. Study 2 data were collected from 300 nurses in 17 adult, paediatric and neonatal units. Nurses rated their workload using the NASA-TLX's paper version. A single factor model testing whether all six items measured a single overall workload variable fit least well (RMSEA = 0.14; CFI = 0.91; TLI = 0.85). A second model that specified two items as outcomes of overall workload had acceptable fit (RMSEA = 0.08; CFI = 0.97; TLI = 0.95) while a third model of four items fit best (RMSEA = 0.06; CFI > 0.99; TLI = 0.99). A summed score from four of six NASA-TLX items appears to most reliably measure a single overall workload variable among intensive care nurses. Copyright © 2018 Elsevier Ltd. All rights reserved.

Steady-state signatures of visual perceptual load, multimodal distractor filtering, and neural competition.

PubMed

Parks, Nathan A; Hilimire, Matthew R; Corballis, Paul M

2011-05-01

The perceptual load theory of attention posits that attentional selection occurs early in processing when a task is perceptually demanding but occurs late in processing otherwise. We used a frequency-tagged steady-state evoked potential paradigm to investigate the modality specificity of perceptual load-induced distractor filtering and the nature of neural-competitive interactions between task and distractor stimuli. EEG data were recorded while participants monitored a stream of stimuli occurring in rapid serial visual presentation (RSVP) for the appearance of previously assigned targets. Perceptual load was manipulated by assigning targets that were identifiable by color alone (low load) or by the conjunction of color and orientation (high load). The RSVP task was performed alone and in the presence of task-irrelevant visual and auditory distractors. The RSVP stimuli, visual distractors, and auditory distractors were "tagged" by modulating each at a unique frequency (2.5, 8.5, and 40.0 Hz, respectively), which allowed each to be analyzed separately in the frequency domain. We report three important findings regarding the neural mechanisms of perceptual load. First, we replicated previous findings of within-modality distractor filtering and demonstrated a reduction in visual distractor signals with high perceptual load. Second, auditory steady-state distractor signals were unaffected by manipulations of visual perceptual load, consistent with the idea that perceptual load-induced distractor filtering is modality specific. Third, analysis of task-related signals revealed that visual distractors competed with task stimuli for representation and that increased perceptual load appeared to resolve this competition in favor of the task stimulus.

Perceived task complexity of trunk stability exercises.

PubMed

McPhee, Megan; Tucker, Kylie J; Wan, Alan; MacDonald, David A

2017-02-01

Perceived task complexity can impact participation in an exercise programme and the level of skill acquisition resulting from participation. Although trunk stability exercises are commonly included in the management of people with low back pain, potential differences in perceived task complexity between those exercises have not been investigated previously. To investigate the perceived task complexity following first time instruction of two common stability exercises: the abdominal brace and abdominal hollow. Cross-sectional. Twenty-four naïve healthy participants received instruction in the performance of an abdominal brace and an abdominal hollow with feedback. Participants rated their perceived task complexity (mental, physical, and temporal demand, performance, effort, frustration) for each exercise on the NASA-Task Load Index. The abdominal hollow was associated with higher perceived mental demand than the abdominal brace (p = 0.01), and required more time to learn (p < 0.01). The abdominal brace was associated with greater mental demand and frustration when performed after the abdominal hollow than before. This study has provided the first evidence for differences in perceived task complexity between two commonly used trunk stability exercises. Those differences in perceived task complexity may influence the selection of exercises intended to enhance the robustness of spinal stability. Copyright © 2016 Elsevier Ltd. All rights reserved.

The role of working memory in spatial S-R correspondence effects.

PubMed

Wühr, Peter; Biebl, Rupert

2011-04-01

This study investigates the impact of working memory (WM) load on response conflicts arising from spatial (non) correspondence between irrelevant stimulus location and response location (Simon effect). The dominant view attributes the Simon effect to automatic processes of location-based response priming. The automaticity view predicts insensitivity of the Simon effect to manipulations of processing load. Four experiments investigated the role of spatial and verbal WM in horizontal and vertical Simon tasks by using a dual-task approach. Participants maintained different amounts of spatial or verbal information in WM while performing a horizontal or vertical Simon task. Results showed that high load generally decreased, and sometimes eliminated, the Simon effect. It is interesting to note that spatial load had a larger impact than verbal load on the horizontal Simon effect, whereas verbal load had a larger impact than spatial load on the vertical Simon effect. The results highlight the role of WM as the perception-action interface in choice-response tasks. Moreover, the results suggest spatial coding of horizontal stimulus-response (S-R) tasks, and verbal coding of vertical S-R tasks.

Concentration: The Neural Underpinnings of How Cognitive Load Shields Against Distraction.

PubMed

Sörqvist, Patrik; Dahlström, Örjan; Karlsson, Thomas; Rönnberg, Jerker

2016-01-01

Whether cognitive load-and other aspects of task difficulty-increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal-task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information-which decreases distractibility-as a side effect of the increased activity in a focused-attention network.

Dynamic modulation of the perceptual load on microsaccades during a selective spatial attention task.

PubMed

Xue, Linyan; Huang, Dan; Wang, Tong; Hu, Qiyi; Chai, Xinyu; Li, Liming; Chen, Yao

2017-11-28

Selective spatial attention enhances task performance at restricted regions within the visual field. The magnitude of this effect depends on the level of attentional load, which determines the efficiency of distractor rejection. Mechanisms of attentional load include perceptual selection and/or cognitive control involving working memory. Recent studies have provided evidence that microsaccades are influenced by spatial attention. Therefore, microsaccade activities may be exploited to help understand the dynamic control of selective attention under different load levels. However, previous reports in humans on the effect of attentional load on microsaccades are inconsistent, and it is not clear to what extent these results and the dynamic changes of microsaccade activities are similar in monkeys. We trained monkeys to perform a color detection task in which the perceptual load was manipulated by task difficulty with limited involvement of working memory. Our results indicate that during the task with high perceptual load, the rate and amplitude of microsaccades immediately before the target color change were significantly suppressed. We also found that the occurrence of microsaccades before the monkeys' detection response deteriorated their performance, especially in the hard task. We propose that the activity of microsaccades might be an efficacious indicator of the perceptual load.

Personality Traits Moderate the Effect of Workload Sources on Perceived Workload in Flying Column Police Officers

PubMed Central

Chiorri, Carlo; Garbarino, Sergio; Bracco, Fabrizio; Magnavita, Nicola

2015-01-01

Previous research has suggested that personality traits of the Five Factor Model play a role in worker's response to workload. The aim of this study was to investigate the association of personality traits of first responders with their perceived workload in real-life tasks. A flying column of 269 police officers completed a measure of subjective workload (NASA-Task Load Index) after intervention tasks in a major public event. Officers' scores on a measure of Five Factor Model personality traits were obtained from archival data. Linear Mixed Modeling was used to test the direct and interaction effects of personality traits on workload scores once controlling for background variables, task type and workload source (mental, temporal and physical demand of the task, perceived effort, dissatisfaction for the performance and frustration due to the task). All personality traits except extraversion significantly interacted at least with one workload source. Perceived workload in flying column police officers appears to be the result of their personality characteristics interacting with the workload source. The implications of these results for the development of support measures aimed at reducing the impact of workload in this category of workers are discussed. PMID:26640456

Robotic assistance improves intracorporeal suturing performance and safety in the operating room while decreasing operator workload.

PubMed

Stefanidis, Dimitrios; Wang, Fikre; Korndorffer, James R; Dunne, J Bruce; Scott, Daniel J

2010-02-01

Intracorporeal suturing is one of the most difficult laparoscopic tasks. The purpose of this study was to assess the impact of robotic assistance on novice suturing performance, safety, and workload in the operating room. Medical students (n = 34), without prior laparoscopic suturing experience, were enrolled in an Institutional Review Board-approved, randomized protocol. After viewing an instructional video, subjects were tested in intracorporeal suturing on two identical, live, porcine Nissen fundoplication models; they placed three gastro-gastric sutures using conventional laparoscopic instruments in one model and using robotic assistance (da Vinci) in the other, in random order. Each knot was objectively scored based on time, accuracy, and security. Injuries to surrounding structures were recorded. Workload was assessed using the validated National Aeronautics and Space Administration (NASA) task load index (TLX) questionnaire, which measures the subjects' self-reported performance, effort, frustration, and mental, physical, and temporal demands of the task. Analysis was by paired t-test; p < 0.05 was considered significant. Compared with laparoscopy, robotic assistance enabled subjects to suture faster (595 +/- 22 s versus 459 +/- 137 s, respectively; p < 0.001), achieve higher overall scores (0 +/- 1 versus 95 +/- 128, respectively; p < 0.001), and commit fewer errors per knot (1.15 +/- 1.35 versus 0.05 +/- 0.26, respectively; p < 0.001). Subjects' overall score did not improve between the first and third attempt for laparoscopic suturing (0 +/- 0 versus 0 +/- 0; p = NS) but improved significantly for robotic suturing (49 +/- 100 versus 141 +/- 152; p < 0.001). Moreover, subjects indicated on the NASA-TLX scale that the task was more difficult to perform with laparoscopic instruments compared with robotic assistance (99 +/- 15 versus 57 +/- 23; p < 0.001). Compared with standard laparoscopy, robotic assistance significantly improved intracorporeal suturing performance and safety of novices in the operating room while decreasing their workload. Moreover, the robot significantly shortened the learning curve of this difficult task. Further study is needed to assess the value of robotic assistance for experienced surgeons, and validated robotic training curricula need to be developed.

Measuring mental workload: ocular astigmatism aberration as a novel objective index.

PubMed

Jiménez, Raimundo; Cárdenas, David; González-Anera, Rosario; Jiménez, José R; Vera, Jesús

2018-04-01

This study assessed the effect of two perceptually matched mental tasks with different levels of mental demand on ocular aberrations in a group of young adults. We measured ocular aberration with a wavefront sensor, and total, internal and corneal RMS (root mean square) aberrations were calculated from Zernike coefficients, considering natural and scaled pupils (5, 4.5, and 4 mm). We found that total, internal and corneal astigmatism RMS showed significant differences between mental tasks with natural pupils (p < .05), and this effect was maintained with 5 mm scaled pupils (total RMS astigmatism, p < .05). Consistently, pupil size, intraocular pressure, perceived mental load and cognitive performance were influenced by the level of mental complexity (p < .05 for all). The findings suggest that ocular astigmatism aberration, mediated by intraocular pressure, could be an objective, valid reliable index to evaluate the impact of cognitive processing in conjunction with others physiological markers in real world contexts. Practitioner Summary: The search continues for a valid, reliable, convenient method of measuring mental workload. In this study we found ocular astigmatism aberration is sensitive to the cumulative effect of mental effort. It shows promise of being a novel ocular index which may help to assess mental workload in real situations.

Effects of cognitive appraisal and mental workload factors on performance in an arithmetic task.

PubMed

Galy, Edith; Mélan, Claudine

2015-12-01

We showed in a previous study an additive interaction between intrinsic and extraneous cognitive loads and of participants' alertness in an 1-back working memory task. The interaction between intrinsic and extraneous cognitive loads was only observed when participants' alertness was low (i.e. in the morning). As alertness is known to reflect an individual's general functional state, we suggested that the working memory capacity available for germane cognitive load depends on a participant's functional state, in addition to intrinsic and extraneous loads induced by the task and task conditions. The relationships between the different load types and their assessment by specific load measures gave rise to a modified cognitive load model. The aim of the present study was to complete the model by determining to what extent and at what processing level an individual's characteristics intervene in order to implement efficient strategies in a working memory task. Therefore, the study explored participants' cognitive appraisal of the situation in addition to the load factors considered previously-task difficulty, time pressure and alertness. Each participant performed a mental arithmetic task in four different cognitive load conditions (crossover of two task difficulty conditions and of two time pressure conditions), both while their alertness was low (9 a.m.) and high (4 p.m.). Results confirmed an additive effect of task difficulty and time pressure, previously reported in the 1-back memory task, thereby lending further support to the modified cognitive load model. Further, in the high intrinsic and extraneous load condition, performance was reduced on the morning session (i.e. when alertness was low) on one hand, and in those participants' having a threat appraisal of the situation on the other hand. When these factors were included into the analysis, a performance drop occurred in the morning irrespective of cognitive appraisal, and with threat appraisal in the afternoon (i.e. high alertness). Taken together, these findings indicate that mental overload can be the result of a combination of subject-related characteristics, including alertness and cognitive appraisal, in addition to well-documented task-related components (intrinsic and extraneous load). As the factors investigated in the study are known to be critically involved in a number of real job-activities, the findings suggest that solutions designed to reduce incidents and accidents at work should consider the situation from a global perspective, including individual characteristics, task parameters, and work organization, rather than dealing with each factor separately.

Predicting workload profiles of brain-robot interface and electromygraphic neurofeedback with cortical resting-state networks: personal trait or task-specific challenge?

NASA Astrophysics Data System (ADS)

Fels, Meike; Bauer, Robert; Gharabaghi, Alireza

2015-08-01

Objective. Novel rehabilitation strategies apply robot-assisted exercises and neurofeedback tasks to facilitate intensive motor training. We aimed to disentangle task-specific and subject-related contributions to the perceived workload of these interventions and the related cortical activation patterns. Approach. We assessed the perceived workload with the NASA Task Load Index in twenty-one subjects who were exposed to two different feedback tasks in a cross-over design: (i) brain-robot interface (BRI) with haptic/proprioceptive feedback of sensorimotor oscillations related to motor imagery, and (ii) control of neuromuscular activity with feedback of the electromyography (EMG) of the same hand. We also used electroencephalography to examine the cortical activation patterns beforehand in resting state and during the training session of each task. Main results. The workload profile of BRI feedback differed from EMG feedback and was particularly characterized by the experience of frustration. The frustration level was highly correlated across tasks, suggesting subject-related relevance of this workload component. Those subjects who were specifically challenged by the respective tasks could be detected by an interhemispheric alpha-band network in resting state before the training and by their sensorimotor theta-band activation pattern during the exercise. Significance. Neurophysiological profiles in resting state and during the exercise may provide task-independent workload markers for monitoring and matching participants’ ability and task difficulty of neurofeedback interventions.

Failure tolerance strategy of space manipulator for large load carrying tasks

NASA Astrophysics Data System (ADS)

Chen, Gang; Yuan, Bonan; Jia, Qingxuan; Sun, Hanxu; Guo, Wen

2018-07-01

During the execution of large load carrying tasks in long term service, there is a notable risk of space manipulator suffering from locked-joint failure, thus space manipulator should be with enough failure tolerance performance. A research on evaluating failure tolerance performance and re-planning feasible task trajectory for space manipulator performing large load carrying tasks is conducted in this paper. The effects of locked-joint failure on critical performance(reachability and load carrying capacity) of space manipulator are analyzed at first. According to the requirements of load carrying tasks, we further propose a new concept of failure tolerance workspace with load carrying capacity(FTWLCC) to evaluate failure tolerance performance, and improve the classic A* algorithm to search the feasible task trajectory. Through the normalized FTWLCC and the improved A* algorithm, the reachability and load carrying capacity of the degraded space manipulator are evaluated, and the reachable and capable trajectory can be obtained. The establishment of FTWLCC provides a novel idea that combines mathematical statistics with failure tolerance performance to illustrate the distribution of load carrying capacity in three-dimensional space, so multiple performance indices can be analyzed simultaneously and visually. And the full consideration of all possible failure situations and motion states makes FTWLCC and improved A* algorithm be universal and effective enough to be appropriate for random joint failure and variety of requirement of large load carrying tasks, so they can be extended to other types of manipulators.

[Creation and normalisation of a verbal episodic memory task in elderly adults: "GERIA-12"].

PubMed

Vandenberghe, M; Michiels, J; Vanderaspoilden, V; Claes, T; Fery, P

2015-12-01

Early damage to episodic memory encoding and consolidation processes has been demonstrated in dementia of the Alzheimer type. However, in the domain of verbal episodic memory assessment, there are few diagnostic tools adapted to the old and oldest old as far as ease of administration and accuracy of normative data are concerned. Classic tasks are either too effortful (like the free recall/cued recall of 16 items), not sensitive enough (like the 5 words test), or insufficiently accurate for people above 70 years old in terms of normative data. The aim of this study was to develop a reduced task (in terms of number of items and number of trials) assessing verbal episodic memory in people aged between 70 and 89 years old. The task (GERIA-12) used the same procedure as the RL/RI-16 task but the list comprised only 12 words and there were only 2 learning trials. In order to assess consolidation processes, we included 2 delayed recall trials, one after 20 minutes and the other after 24 hours. We also calculated indexes adapted from the Item-Specific Deficit Approach developed by Wright et al., which has the advantage of providing measures specific to encoding, consolidation and retrieval processes. Standardization was done with data from 220 people aged between 70 and 89 years old and belonging to 3 education levels. We obtained a significant effect of age and education level: scores decrease with age and increase with education. Norms have thus been calculated taking those two variables into consideration. Concerning the standardization, Barona method has been used for free recall scores while percentiles have been used for all other scores (total recall, free recall, encoding, consolidation and retrieval indexes). Normative data are also provided for intrusions and perseverations. This new task allows encoding, consolidation and retrieval processes assessment in older people and has the following advantages: the procedure is more suitable (ease and time of administration), there are accurate normative data for old and oldest old people, and there are normative data for two delayed recalls (at 20 minutes and at 24 hours). Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Task-irrelevant memory load induces inattentional blindness without temporo-parietal suppression.

PubMed

Matsuyoshi, Daisuke; Ikeda, Takashi; Sawamoto, Nobukatsu; Kakigi, Ryusuke; Fukuyama, Hidenao; Osaka, Naoyuki

2010-08-01

We often fail to consciously detect an unexpected object when we are engaged in an attention-demanding task (inattentional blindness). The inattentional blindness which is induced by visual short-term memory (VSTM) load has been proposed to result from a suppression of temporo-parietal junction (TPJ) activity that involves stimulus-driven attention. However, the fact that, inversely proportional to TPJ activity, intraparietal sulcus (IPS) activity correlates with VSTM load renders questionable the account of inattentional blindness based only on TPJ activity. Here, we investigated whether the TPJ is solely responsible for inattentional blindness by decoupling IPS and TPJ responses to VSTM load and then using the same manipulation to test the behavioral inattentional blindness performance. Experiment 1 showed that TPJ activity was not suppressed by task-irrelevant load while the IPS responded to both task-relevant and task-irrelevant load. Although the TPJ account of inattentional blindness predicts that the degree of inattentional blindness should track TPJ activity, we found in Experiment 2 that inattentional blindness was induced not only by task-relevant load but also by task-irrelevant load, showing inconsistency between the extent of inattentional blindness and TPJ response. These findings suggest that inattentional blindness can be induced without suppression of TPJ activity and seem to offer the possibility that the IPS contributes to conscious perception. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Classifying Drivers' Cognitive Load Using EEG Signals.

PubMed

Barua, Shaibal; Ahmed, Mobyen Uddin; Begum, Shahina

2017-01-01

A growing traffic safety issue is the effect of cognitive loading activities on traffic safety and driving performance. To monitor drivers' mental state, understanding cognitive load is important since while driving, performing cognitively loading secondary tasks, for example talking on the phone, can affect the performance in the primary task, i.e. driving. Electroencephalography (EEG) is one of the reliable measures of cognitive load that can detect the changes in instantaneous load and effect of cognitively loading secondary task. In this driving simulator study, 1-back task is carried out while the driver performs three different simulated driving scenarios. This paper presents an EEG based approach to classify a drivers' level of cognitive load using Case-Based Reasoning (CBR). The results show that for each individual scenario as well as using data combined from the different scenarios, CBR based system achieved approximately over 70% of classification accuracy.

Effects on automatic attention due to exposure to pictures of emotional faces while performing Chinese word judgment tasks.

PubMed

Junhong, Huang; Renlai, Zhou; Senqi, Hu

2013-01-01

Two experiments were conducted to investigate the automatic processing of emotional facial expressions while performing low or high demand cognitive tasks under unattended conditions. In Experiment 1, 35 subjects performed low (judging the structure of Chinese words) and high (judging the tone of Chinese words) cognitive load tasks while exposed to unattended pictures of fearful, neutral, or happy faces. The results revealed that the reaction time was slower and the performance accuracy was higher while performing the low cognitive load task than while performing the high cognitive load task. Exposure to fearful faces resulted in significantly longer reaction times and lower accuracy than exposure to neutral faces on the low cognitive load task. In Experiment 2, 26 subjects performed the same word judgment tasks and their brain event-related potentials (ERPs) were measured for a period of 800 ms after the onset of the task stimulus. The amplitudes of the early component of ERP around 176 ms (P2) elicited by unattended fearful faces over frontal-central-parietal recording sites was significantly larger than those elicited by unattended neutral faces while performing the word structure judgment task. Together, the findings of the two experiments indicated that unattended fearful faces captured significantly more attention resources than unattended neutral faces on a low cognitive load task, but not on a high cognitive load task. It was concluded that fearful faces could automatically capture attention if residues of attention resources were available under the unattended condition.

Effects on Automatic Attention Due to Exposure to Pictures of Emotional Faces while Performing Chinese Word Judgment Tasks

PubMed Central

Junhong, Huang; Renlai, Zhou; Senqi, Hu

2013-01-01

Two experiments were conducted to investigate the automatic processing of emotional facial expressions while performing low or high demand cognitive tasks under unattended conditions. In Experiment 1, 35 subjects performed low (judging the structure of Chinese words) and high (judging the tone of Chinese words) cognitive load tasks while exposed to unattended pictures of fearful, neutral, or happy faces. The results revealed that the reaction time was slower and the performance accuracy was higher while performing the low cognitive load task than while performing the high cognitive load task. Exposure to fearful faces resulted in significantly longer reaction times and lower accuracy than exposure to neutral faces on the low cognitive load task. In Experiment 2, 26 subjects performed the same word judgment tasks and their brain event-related potentials (ERPs) were measured for a period of 800 ms after the onset of the task stimulus. The amplitudes of the early component of ERP around 176 ms (P2) elicited by unattended fearful faces over frontal-central-parietal recording sites was significantly larger than those elicited by unattended neutral faces while performing the word structure judgment task. Together, the findings of the two experiments indicated that unattended fearful faces captured significantly more attention resources than unattended neutral faces on a low cognitive load task, but not on a high cognitive load task. It was concluded that fearful faces could automatically capture attention if residues of attention resources were available under the unattended condition. PMID:24124486

To hear or not to hear: Voice processing under visual load.

PubMed

Zäske, Romi; Perlich, Marie-Christin; Schweinberger, Stefan R

2016-07-01

Adaptation to female voices causes subsequent voices to be perceived as more male, and vice versa. This contrastive aftereffect disappears under spatial inattention to adaptors, suggesting that voices are not encoded automatically. According to Lavie, Hirst, de Fockert, and Viding (2004), the processing of task-irrelevant stimuli during selective attention depends on perceptual resources and working memory. Possibly due to their social significance, faces may be an exceptional domain: That is, task-irrelevant faces can escape perceptual load effects. Here we tested voice processing, to study whether voice gender aftereffects (VGAEs) depend on low or high perceptual (Exp. 1) or working memory (Exp. 2) load in a relevant visual task. Participants adapted to irrelevant voices while either searching digit displays for a target (Exp. 1) or recognizing studied digits (Exp. 2). We found that the VGAE was unaffected by perceptual load, indicating that task-irrelevant voices, like faces, can also escape perceptual-load effects. Intriguingly, the VGAE was increased under high memory load. Therefore, visual working memory load, but not general perceptual load, determines the processing of task-irrelevant voices.

Fine and gross motor skills: The effects on skill-focused dual-tasks.

PubMed

Raisbeck, Louisa D; Diekfuss, Jed A

2015-10-01

Dual-task methodology often directs participants' attention towards a gross motor skill involved in the execution of a skill, but researchers have not investigated the comparative effects of attention on fine motor skill tasks. Furthermore, there is limited information about participants' subjective perception of workload with respect to task performance. To examine this, the current study administered the NASA-Task Load Index following a simulated shooting dual-task. The task required participants to stand 15 feet from a projector screen which depicted virtual targets and fire a modified Glock 17 handgun equipped with an infrared laser. Participants performed the primary shooting task alone (control), or were also instructed to focus their attention on a gross motor skill relevant to task execution (gross skill-focused) and a fine motor skill relevant to task execution (fine skill-focused). Results revealed that workload was significantly greater during the fine skill-focused task for both skill levels, but performance was only affected for the lesser-skilled participants. Shooting performance for the lesser-skilled participants was greater during the gross skill-focused condition compared to the fine skill-focused condition. Correlational analyses also demonstrated a significant negative relationship between shooting performance and workload during the gross skill-focused task for the higher-skilled participants. A discussion of the relationship between skill type, workload, skill level, and performance in dual-task paradigms is presented. Copyright © 2015 Elsevier B.V. All rights reserved.

Weight and See: Loading Working Memory Improves Incidental Identification of Irrelevant Faces

PubMed Central

Carmel, David; Fairnie, Jake; Lavie, Nilli

2012-01-01

Are task-irrelevant stimuli processed to a level enabling individual identification? This question is central both for perceptual processing models and for applied settings (e.g., eye-witness testimony). Lavie’s load theory proposes that working memory actively maintains attentional prioritization of relevant over irrelevant information. Loading working memory thus impairs attentional prioritization, leading to increased processing of task-irrelevant stimuli. Previous research has shown that increased working memory load leads to greater interference effects from response-competing distractors. Here we test the novel prediction that increased processing of irrelevant stimuli under high working memory load should lead to a greater likelihood of incidental identification of entirely irrelevant stimuli. To test this, we asked participants to perform a word-categorization task while ignoring task-irrelevant images. The categorization task was performed during the retention interval of a working memory task with either low or high load (defined by memory set size). Following the final experimental trial, a surprise question assessed incidental identification of the irrelevant image. Loading working memory was found to improve identification of task-irrelevant faces, but not of building stimuli (shown in a separate experiment to be less distracting). These findings suggest that working memory plays a critical role in determining whether distracting stimuli will be subsequently identified. PMID:22912623

Effects of Nicotine Deprivation on Craving Response Covariation in Smokers

PubMed Central

Sayette, Michael A.; Martin, Christopher S.; Hull, Jay G.; Wertz, Joan M.; Perrott, Michael A.

2009-01-01

Most models of craving propose that when cravings are strong, diverse responses—thought to index an underlying craving state— covary. Previous studies provided weak support for this hypothesis. The authors tested whether nicotine deprivation affects degree of covariation across multiple measures related to craving. Heavy and light smokers (N = 127) were exposed to smoking cues while either nicotine deprived or nondeprived. Measures included urge ratings, affective valence, a behavioral choice task assessing perceived reinforcement value of smoking, and smoking-related judgment tasks. Results indicated higher correlations in the nicotine-deprived than in nondeprived group. The measures principally responsible for this effect loaded onto a single common Craving factor for nicotine-deprived but not nondeprived smokers. These findings suggest that, under certain conditions, measures of craving-related processes covary. PMID:12653419

Enhancing Human-Machine System Performance by Introducing Artificial Cognition in Vehicle Guidance Work Systems

DTIC Science & Technology

2009-10-01

evaluated after each mission using the NASA - TLX method [21]. Moreover, they were interviewed to be able to state problems and suggest system...France, 3 rd -4 th September 2008. [21] Sandra G. Hart & Lowell E. Staveland (1988). Development of NASA - TLX (Task Load Index): Results of...o b s e rv a b le b e h a v io u r o f C P = A C U b e h a v io u r Interpretation Figure 11: The Cognitive Process for generating knowledge

A crossmodal crossover: opposite effects of visual and auditory perceptual load on steady-state evoked potentials to irrelevant visual stimuli.

PubMed

Jacoby, Oscar; Hall, Sarah E; Mattingley, Jason B

2012-07-16

Mechanisms of attention are required to prioritise goal-relevant sensory events under conditions of stimulus competition. According to the perceptual load model of attention, the extent to which task-irrelevant inputs are processed is determined by the relative demands of discriminating the target: the more perceptually demanding the target task, the less unattended stimuli will be processed. Although much evidence supports the perceptual load model for competing stimuli within a single sensory modality, the effects of perceptual load in one modality on distractor processing in another is less clear. Here we used steady-state evoked potentials (SSEPs) to measure neural responses to irrelevant visual checkerboard stimuli while participants performed either a visual or auditory task that varied in perceptual load. Consistent with perceptual load theory, increasing visual task load suppressed SSEPs to the ignored visual checkerboards. In contrast, increasing auditory task load enhanced SSEPs to the ignored visual checkerboards. This enhanced neural response to irrelevant visual stimuli under auditory load suggests that exhausting capacity within one modality selectively compromises inhibitory processes required for filtering stimuli in another. Copyright © 2012 Elsevier Inc. All rights reserved.

Effects of running with backpack loads during simulated gravitational transitions: Improvements in postural control

NASA Astrophysics Data System (ADS)

Brewer, Jeffrey David

The National Aeronautics and Space Administration is planning for long-duration manned missions to the Moon and Mars. For feasible long-duration space travel, improvements in exercise countermeasures are necessary to maintain cardiovascular fitness, bone mass throughout the body and the ability to perform coordinated movements in a constant gravitational environment that is six orders of magnitude higher than the "near weightlessness" condition experienced during transit to and/or orbit of the Moon, Mars, and Earth. In such gravitational transitions feedback and feedforward postural control strategies must be recalibrated to ensure optimal locomotion performance. In order to investigate methods of improving postural control adaptation during these gravitational transitions, a treadmill based precision stepping task was developed to reveal changes in neuromuscular control of locomotion following both simulated partial gravity exposure and post-simulation exercise countermeasures designed to speed lower extremity impedance adjustment mechanisms. The exercise countermeasures included a short period of running with or without backpack loads immediately after partial gravity running. A novel suspension type partial gravity simulator incorporating spring balancers and a motor-driven treadmill was developed to facilitate body weight off loading and various gait patterns in both simulated partial and full gravitational environments. Studies have provided evidence that suggests: the environmental simulator constructed for this thesis effort does induce locomotor adaptations following partial gravity running; the precision stepping task may be a helpful test for illuminating these adaptations; and musculoskeletal loading in the form of running with or without backpack loads may improve the locomotor adaptation process.

Concentration: The Neural Underpinnings of How Cognitive Load Shields Against Distraction

PubMed Central

Sörqvist, Patrik; Dahlström, Örjan; Karlsson, Thomas; Rönnberg, Jerker

2016-01-01

Whether cognitive load—and other aspects of task difficulty—increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal-task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information—which decreases distractibility—as a side effect of the increased activity in a focused-attention network. PMID:27242485

Operation Compatibility: A Neglected Contribution to Dual-Task Costs

ERIC Educational Resources Information Center

Pannebakker, Merel M.; Band, Guido P. H.; Ridderinkhof, K. Richard

2009-01-01

Traditionally, dual-task interference has been attributed to the consequences of task load exceeding capacity limitations. However, the current study demonstrates that in addition to task load, the mutual compatibility of the concurrent processes modulates whether 2 tasks can be performed in parallel. In 2 psychological refractory period…

Physician work intensity among medical specialties: emerging evidence on its magnitude and composition.

PubMed

Horner, Ronnie D; Szaflarski, Jerzy P; Ying, Jun; Meganathan, Karthikeyan; Matthews, Gerald; Schroer, Brian; Weber, Debra; Raphaelson, Marc

2011-11-01

Similarities and differences in physician work intensity among specialties are poorly understood but have implications for quality of care, patient safety, practice organization and management, and payment. To determine the magnitude and important dimensions of physician work intensity for 4 specialties. Cross-sectional assessment of work intensity associated with actual patient care in the examination room or operating room. A convenience sample of 45 family physicians, 20 general internists, 22 neurologists, and 21 surgeons, located in Kansas, Kentucky, Maryland, Ohio, and Virginia. Work intensity measures included the National Aeronautics and Space Administration-Task Load Index (NASA-TLX), Subjective Work Assessment Technique (SWAT), and Multiple Resource Questionnaire. Stress was measured by the Dundee Stress State Questionnaire. Physicians reported similar magnitude of work intensity on the NASA-TLX and Multiple Resource Questionnaire. On the SWAT, general internists reported work intensity similar to surgeons but significantly lower than family physicians and neurologists (P=0.035). Surgeons reported significantly higher levels of task engagement on the stress measure than the other specialties (P=0.019), significantly higher intensity on physical demand (P < 0.001), and significantly lower intensity on the performance dimensions of the NASA-TLX than the other specialties (P=0.003). Surgeons reported the lowest intensity for temporal demand of all specialties, being significantly lower than either family physicians or neurologists (P=0.014). Family physicians reported the highest intensity on the time dimension of the SWAT, being significantly higher than either general internists or surgeons (P=0.008). Level of physician work intensity seems to be similar among specialties.

The effect of a concurrent working memory task and temporal offsets on the integration of auditory and visual speech information.

PubMed

Buchan, Julie N; Munhall, Kevin G

2012-01-01

Audiovisual speech perception is an everyday occurrence of multisensory integration. Conflicting visual speech information can influence the perception of acoustic speech (namely the McGurk effect), and auditory and visual speech are integrated over a rather wide range of temporal offsets. This research examined whether the addition of a concurrent cognitive load task would affect the audiovisual integration in a McGurk speech task and whether the cognitive load task would cause more interference at increasing offsets. The amount of integration was measured by the proportion of responses in incongruent trials that did not correspond to the audio (McGurk response). An eye-tracker was also used to examine whether the amount of temporal offset and the presence of a concurrent cognitive load task would influence gaze behavior. Results from this experiment show a very modest but statistically significant decrease in the number of McGurk responses when subjects also perform a cognitive load task, and that this effect is relatively constant across the various temporal offsets. Participant's gaze behavior was also influenced by the addition of a cognitive load task. Gaze was less centralized on the face, less time was spent looking at the mouth and more time was spent looking at the eyes, when a concurrent cognitive load task was added to the speech task.

Exploratory factor analysis of the functional movement screen in elite athletes.

PubMed

Li, Yongming; Wang, Xiong; Chen, Xiaoping; Dai, Boyi

2015-01-01

The functional movement screen is developed to examine individuals' movement patterns through 7 functional tasks. The purpose of this study was to identify the internal consistency and factor structure of the 7 tasks of the functional movement screen in elite athletes; 290 elite athletes from a variety of Chinese national teams were assessed using the functional movement screen. Cronbach's alpha was calculated for the scores of the 7 tasks. Exploratory factor analysis was performed to explore the factor structure of the functional movement screen. The mean and standard deviation of the sum score were 15.2 ± 3.0. A low Cronbach's alpha (0.58) was found for the scores of the 7 tasks. Exploratory factor analysis extracted 2 factors with eigenvalues greater than 1, and these 2 factors explained 47.3% of the total variance. The first factor had a high loading on the rotatory stability (loading = 0.99) and low loadings on the other 6 tasks (loading range: 0.04-0.34). The second factor had high loadings on the deep squat, hurdle step and inline lunge (loading range: 0.46-0.61) and low loadings on the other 3 tasks (loading range: 0.12-0.32). The 7 tasks of the functional movement screen had low internal consistency and were not indicators of a single factor. Evidence for unidimensionality was not found for the functional movement screen in elite athletes. More attention should be paid to the score of each task rather than the sum score when we interpret the functional movement screen scores.

Occupational Lifting Tasks and Retinal Detachment in Non-Myopics and Myopics: Extended Analysis of a Case-Control Study

PubMed Central

Mattioli, Stefano; Curti, Stefania; De Fazio, Rocco; Mt Cooke, Robin; Zanardi, Francesca; Bonfiglioli, Roberta; Violante, Francesco S

2012-01-01

Objectives Lifting heavy weights involves the Valsalva manoeuvre, which leads to intraocular pressure spikes. We used data from a case-control study to further investigate the hypothesis that occupational lifting is a risk factor for retinal detachment. Methods The study population included 48 cases (patients operated for retinal detachment) and 84 controls (outpatients attending an eye clinic). The odds ratios (OR) of idiopathic retinal detachment were estimated with a logistic regression model (adjusted for age, sex and body mass index). Three indexes were used to examine exposure to lifting; 1) maximum load lifted, 2) average weekly lifting, 3) lifelong cumulative lifting. Results For all indexes, the most exposed subjects showed an increased risk of retinal detachment compared with the unexposed (index 1: OR 3.57, 95% confidence interval [CI] 1.21-10.48; index 2: OR 3.24, 95% CI 1.32-7.97; index 3: OR 2.23, 95% CI 1.27-8.74) and dose-response relationships were apparent. Conclusion These results reinforce the hypothesis that heavy occupational lifting may be a relevant risk factor for retinal detachment. PMID:22953231

Flexible muscle modes and synergies in challenging whole-body tasks.

PubMed

Danna-Dos-Santos, Alessander; Degani, Adriana M; Latash, Mark L

2008-08-01

We used the idea of hierarchical control to study multi-muscle synergies during a whole-body sway task performed by a standing person. Within this view, at the lower level of the hierarchy, muscles are united into groups (M-modes). At the higher level, gains at the M-modes are co-varied by the controller in a task-specific way to ensure low variability of important physical variables. In particular, we hypothesized that (1) the composition of M-modes could adjust and (2) an index of M-mode co-variation would become weaker in more challenging conditions. Subjects were required to perform a whole-body sway at 0.5 Hz paced by a metronome. They performed the task with eyes open and closed, while standing on both feet or on one foot only, with and without vibration applied to the Achilles tendons. Integrated indices of muscle activation were subjected to principal component analysis to identify M-modes. An increase in the task complexity led to an increase in the number of principal components that contained significantly loaded indices of muscle activation from 3 to 5. Hence, in more challenging tasks, the controller manipulated a larger number of variables. Multiple regression analysis was used to define the Jacobian of the system mapping small changes in M-mode gains onto shifts of the center of pressure (COP) in the anterior-posterior direction. Further, the variance in the M-mode space across sway cycles was partitioned into two components, one that did not affect an average across cycles COP coordinate and the other that did (good and bad variance, respectively). Under all conditions, the subjects showed substantially more good variance than bad variance interpreted as a multi-M-mode synergy stabilizing the COP trajectory. An index of the strength of the synergy was comparable across all conditions, and there was no modulation of this index over the sway cycle. Hence, our first hypothesis that the composition of M-modes could adjust under challenging conditions has been confirmed while the second hypothesis stating that the index of M-mode co-variation would become weaker in more challenging conditions has been falsified. We interpret the observations as suggesting that adjustments at the lower level of the hierarchy-in the M-mode composition-allowed the subjects to maintain a comparable level of stabilization of the COP trajectory in more challenging tasks. The findings support the (at least) two-level hierarchical control scheme of whole-body movements.

Flexible Muscle Modes and Synergies in Challenging Whole-Body Tasks

PubMed Central

Danna-dos-Santos, Alessander; Degani, Adriana M.; Latash, Mark L.

2008-01-01

We used the idea of hierarchical control to study multi-muscle synergies during a whole-body sway task performed by a standing person. Within this view, at the lower level of the hierarchy, muscles are united into groups (M-modes). At the higher level, gains at the M-modes are co-varied by the controller in a task specific way to ensure low variability of important physical variables. In particular, we hypothesized that (1) the composition of M-modes could adjust and (2) an index of M-mode co-variation would become weaker in more challenging conditions. Subjects were required to perform a whole-body sway at 0.5 Hz paced by a metronome. They performed the task with eyes open and closed, while standing on both feet or on one foot only, with and without vibration applied to the Achilles tendons. Integrated indices of muscle activation were subjected to principal component analysis to identify M-modes. An increase in the task complexity led to an increase in the number of principal components that contained significantly loaded indices of muscle activation from 3 to 5. Hence, in more challenging tasks, the controller manipulated a larger number of variables. Multiple regression analysis was used to define the Jacobian of the system mapping small changes in M-mode gains onto shifts of the center of pressure (COP) in the anterior-posterior direction. Further, the variance in the M-mode space across sway cycles was partitioned into two components, one that did not affect an average across cycles COP coordinate and the other that did (good and bad variance, respectively). Under all conditions, the subjects showed substantially more good variance than bad variance interpreted as a multi-M-mode synergy stabilizing the COP trajectory. An index of the strength of the synergy was comparable across all conditions, and there was no modulation of this index over the sway cycle. Hence, our first hypothesis that the composition of M-modes could adjust under challenging conditions has been confirmed while the second hypothesis stating that the index of M-mode co-variation would become weaker in more challenging conditions has been falsified. We interpret the observations as suggesting that adjustments at the lower level of the hierarchy - in the M-mode composition - allowed the subjects to maintain a comparable level of stabilization of the COP trajectory in more challenging tasks. The findings support the (at least) two-level hierarchical control scheme of whole-body movements. PMID:18521583

Dual-task and anticipation impact lower limb biomechanics during a single-leg cut with body borne load.

PubMed

Seymore, Kayla D; Cameron, Sarah E; Kaplan, Jonathan T; Ramsay, John W; Brown, Tyler N

2017-12-08

This study quantified how a dual cognitive task impacts lower limb biomechanics during anticipated and unanticipated single-leg cuts with body borne load. Twenty-four males performed anticipated and unanticipated cuts with and without a dual cognitive task with three load conditions: no load (∼6 kg), medium load (15% of BW), and heavy load (30% of BW). Lower limb biomechanics were submitted to a repeated measures linear mixed model to test the main and interaction effects of load, anticipation, and dual task. With body borne load, participants increased peak stance (PS) hip flexion (p = .004) and hip internal rotation (p = .001) angle, and PS hip flexion (p = .001) and internal rotation (p = .018), and knee flexion (p = .016) and abduction (p = .001) moments. With the dual task, participants decreased PS knee flexion angle (p < .001) and hip flexion moment (p = .027), and increased PS knee external rotation angle (p = .034). During the unanticipated cut, participants increased PS hip (p = .040) and knee flexion angle (p < .001), and decreased PS hip adduction (p = .001), and knee abduction (p = .005) and external rotation (p = .026) moments. Adding body borne load produces lower limb biomechanical adaptations thought to increase risk of musculoskeletal injury, but neither anticipation nor dual task exaggerated those biomechanical adaptations. With a dual task, participants adopted biomechanics known to increase injury risk; whereas, participants used lower limb biomechanics thought to decrease injury risk during unanticipated cuts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multimedia content analysis and indexing: evaluation of a distributed and scalable architecture

NASA Astrophysics Data System (ADS)

Mandviwala, Hasnain; Blackwell, Scott; Weikart, Chris; Van Thong, Jean-Manuel

2003-11-01

Multimedia search engines facilitate the retrieval of documents from large media content archives now available via intranets and the Internet. Over the past several years, many research projects have focused on algorithms for analyzing and indexing media content efficiently. However, special system architectures are required to process large amounts of content from real-time feeds or existing archives. Possible solutions include dedicated distributed architectures for analyzing content rapidly and for making it searchable. The system architecture we propose implements such an approach: a highly distributed and reconfigurable batch media content analyzer that can process media streams and static media repositories. Our distributed media analysis application handles media acquisition, content processing, and document indexing. This collection of modules is orchestrated by a task flow management component, exploiting data and pipeline parallelism in the application. A scheduler manages load balancing and prioritizes the different tasks. Workers implement application-specific modules that can be deployed on an arbitrary number of nodes running different operating systems. Each application module is exposed as a web service, implemented with industry-standard interoperable middleware components such as Microsoft ASP.NET and Sun J2EE. Our system architecture is the next generation system for the multimedia indexing application demonstrated by www.speechbot.com. It can process large volumes of audio recordings with minimal support and maintenance, while running on low-cost commodity hardware. The system has been evaluated on a server farm running concurrent content analysis processes.

Assessment of Attentional Workload while Driving by Eye-fixation-related Potentials

NASA Astrophysics Data System (ADS)

Takeda, Yuji; Yoshitsugu, Noritoshi; Itoh, Kazuya; Kanamori, Nobuhiro

How do drivers cope with the attentional workload of in-vehicle information technology? In the present study, we propose a new psychophysiological measure for assessing drivers' attention: eye-fixation-related potential (EFRP). EFRP is a kind of event-related brain potential measurable at the eye-movement situation that reflects how closely observers examine visual information at the eye-fixated position. In the experiment, the effects of verbal working memory load and spatial working memory load during simulated driving were examined by measuring the number of saccadic eye-movements and EFRP as the indices of drivers' attention. The results showed that the spatial working memory load affected both the number of saccadic eye-movements and the amplitude of the P100 component of EFRP, whereas the verbal working memory load affected only the number of saccadic eye-movements. This implies that drivers can perform time-sharing processing between driving and the verbal working memory task, but the decline of accuracy of visual processing during driving is inescapable when the spatial working memory load is given. The present study suggests that EFRP can provide a new index of drivers' attention, other than saccadic eye-movements.

The Effects of Load Carriage and Physical Fatigue on Cognitive Performance

PubMed Central

Eddy, Marianna D.; Hasselquist, Leif; Giles, Grace; Hayes, Jacqueline F.; Howe, Jessica; Rourke, Jennifer; Coyne, Megan; O’Donovan, Meghan; Batty, Jessica; Brunyé, Tad T.; Mahoney, Caroline R.

2015-01-01

In the current study, ten participants walked for two hours while carrying no load or a 40 kg load. During the second hour, treadmill grade was manipulated between a constant downhill or changing between flat, uphill, and downhill grades. Throughout the prolonged walk, participants performed two cognitive tasks, an auditory go no/go task and a visual target detection task. The main findings were that the number of false alarms increased over time in the loaded condition relative to the unloaded condition on the go no/go auditory task. There were also shifts in response criterion towards responding yes and decreased sensitivity in responding in the loaded condition compared to the unloaded condition. In the visual target detection there were no reliable effects of load carriage in the overall analysis however, there were slower reaction times in the loaded compared to unloaded condition during the second hour. PMID:26154515

Development of Evaluation Indicators for Hospice and Palliative Care Professionals Training Programs in Korea.

PubMed

Kang, Jina; Park, Kyoung-Ok

2017-01-01

The importance of training for Hospice and Palliative Care (HPC) professionals has been increasing with the systemization of HPC in Korea. Hence, the need and importance of training quality for HPC professionals are growing. This study evaluated the construct validity and reliability of the Evaluation Indicators for standard Hospice and Palliative Care Training (EIHPCT) program. As a framework to develop evaluation indicators, an invented theoretical model combining Stufflebeam's CIPP (Context-Input-Process-Product) evaluation model with PRECEDE-PROCEED model was used. To verify the construct validity of the EIHPCT program, a structured survey was performed with 169 professionals who were the HPC training program administrators, trainers, and trainees. To examine the validity of the areas of the EIHPCT program, exploratory factor analysis and confirmatory factor analysis were conducted. First, in the exploratory factor analysis, the indicators with factor loadings above 0.4 were chosen as desirable items, and some cross-loaded items that loaded at 0.4 or higher on two or more factors were adjusted as the higher factor. Second, the model fit of the modified EIHPCT program was quite good in the confirmatory factor analysis (Goodness-of-Fit Index > 0.70, Comparative Fit Index > 0.80, Normed Fit Index > 0.80, Root Mean square of Residuals < 0.05). The modified model of the EIHPCT comprised 4 areas, 13 subdomains, and 61 indicators. The evaluation indicators of the modified model will be valuable references for improving the HPC professional training program.

Marital conflict, respiratory sinus arrhythmia, and allostatic load: Interrelations and associations with the development of children’s externalizing behavior

PubMed Central

El-Sheikh, Mona; Hinnant, J. Benjamin

2011-01-01

Allostatic load theory hypothesizes that stress and the body’s responses to stressors contribute to longer term physiological changes in multiple systems over time (allostasis), and that shifts in how these systems function have implications for adjustment and health. We investigated these hypotheses with longitudinal data from two independent samples (n = 413; 219 girls, 194 boys) with repeated measures at ages 8, 9, 10, and 11. Initial parental marital conflict and its change over time indexed children’s exposure to an important familial stressor, which was examined in interaction with children’s respiratory sinus arrhythmia (RSA) reactivity to laboratory tasks (stress response) to predict children’s basal levels of RSA over time. We also investigated children’s sex as an additional possible moderator. Our second research question focused on examining whether initial levels and changes in resting RSA over time predicted children’s externalizing behavior. Boys with a strong RSA suppression response to a frustrating laboratory task who experienced higher initial marital conflict or increasing marital conflict over time showed decreases in their resting RSA over time. In addition, boys’ initial resting RSA (but not changes in resting RSA over time) was negatively related to change over time in externalizing symptoms. Findings for girls were more mixed. Results are discussed in the context of developmental psychobiology, allostatic load, and implications for the development of psychopathology. PMID:21756434

Marital conflict, respiratory sinus arrhythmia, and allostatic load: interrelations and associations with the development of children's externalizing behavior.

PubMed

El-Sheikh, Mona; Hinnant, J Benjamin

2011-08-01

Allostatic load theory hypothesizes that stress and the body's responses to stressors contribute to longer term physiological changes in multiple systems over time (allostasis), and that shifts in how these systems function have implications for adjustment and health. We investigated these hypotheses with longitudinal data from two independent samples (n = 413; 219 girls, 194 boys) with repeated measures at ages 8, 9, 10, and 11. Initial parental marital conflict and its change over time indexed children's exposure to an important familial stressor, which was examined in interaction with children's respiratory sinus arrhythmia (RSA) reactivity to laboratory tasks (stress response) to predict children's basal levels of RSA over time. We also investigated children's sex as an additional possible moderator. Our second research question focused on examining whether initial levels and changes in resting RSA over time predicted children's externalizing behavior. Boys with a strong RSA suppression response to a frustrating laboratory task who experienced higher initial marital conflict or increasing marital conflict over time showed decreases in their resting RSA over time. In addition, boys' initial resting RSA (but not changes in resting RSA over time) was negatively related to change over time in externalizing symptoms. Findings for girls were more mixed. Results are discussed in the context of developmental psychobiology, allostatic load, and implications for the development of psychopathology.

Perceptual load interacts with stimulus processing across sensory modalities.

PubMed

Klemen, J; Büchel, C; Rose, M

2009-06-01

According to perceptual load theory, processing of task-irrelevant stimuli is limited by the perceptual load of a parallel attended task if both the task and the irrelevant stimuli are presented to the same sensory modality. However, it remains a matter of debate whether the same principles apply to cross-sensory perceptual load and, more generally, what form cross-sensory attentional modulation in early perceptual areas takes in humans. Here we addressed these questions using functional magnetic resonance imaging. Participants undertook an auditory one-back working memory task of low or high perceptual load, while concurrently viewing task-irrelevant images at one of three object visibility levels. The processing of the visual and auditory stimuli was measured in the lateral occipital cortex (LOC) and auditory cortex (AC), respectively. Cross-sensory interference with sensory processing was observed in both the LOC and AC, in accordance with previous results of unisensory perceptual load studies. The present neuroimaging results therefore warrant the extension of perceptual load theory from a unisensory to a cross-sensory context: a validation of this cross-sensory interference effect through behavioural measures would consolidate the findings.

Can we "apply" the findings of Forster and Lavie (2008)? On the generalizability of attentional capture effects under varying levels of perceptual load.

PubMed

Lleras, Alejandro; Chu, Hengqing; Buetti, Simona

2017-06-01

Perceptual Load theory states that the degree of perceptual load on a display determines the amount of leftover attentional resources that the system can use to process distracting information. An important corollary of this theory is that the amount of perceptual load determines the vulnerability of the attention system to being captured by completely irrelevant stimuli, predicting larger amounts of capture with low perceptual load than with high perceptual load. This prediction was first confirmed by Forster and Lavie (2008). Here, we report 6 experiments that followed up on those earlier results, where we find that in many cases, the opposite pattern is obtained: attentional capture increased with increasing perceptual load. Given the lack of generalizability of the theory to new experimental contexts with fairly minor methodological differences, we conclude that Perceptual Load may not be a useful framework for understanding attentional capture. The theoretical and applied importance of these findings is discussed. In particular, we caution against using this theory in applied tasks and settings because best-use recommendations stemming from this theory regarding strategies to decrease distractibility may in fact produce the opposite effect: an increase in distractibility (with distractibility being indexed by the magnitude of the capture effect). (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Preparation, characterization, and biodistribution of letrozole loaded PLGA nanoparticles in Ehrlich Ascites tumor bearing mice.

PubMed

Mondal, Nita; Halder, Kamal Krishna; Kamila, Madan Mohan; Debnath, Mita Chatterjee; Pal, Tapan K; Ghosal, Saroj K; Sarkar, Bharat R; Ganguly, Shantanu

2010-09-15

Letrozole (LTZ) incorporated PLGA nanoparticles were prepared by solvent displacement technique and characterized by transmission electron microscopy, poly-dispersity index and zeta potential measurement. Radiolabeling of free LTZ and LTZ-loaded PLGA NPs was performed with technetium-99m with high labeling efficiency. The labeled complex showed good in vitro stability as verified by DTPA challenge test. The labeled complexes also showed significant in vivo stability when incubated in rat serum for 24 h. Biodistribution studies of (99m)Tc-labeled complexes were performed after intravenous administration in normal mice and Ehrlich Ascites tumor bearing mice. Compared to free LTZ, LTZ-loaded PLGA NPs exhibited significantly lower uptake by the organs of RES. The tumor concentration of LTZ-loaded PLGA NPs was 4.65 times higher than that of free LTZ at 4 h post-injection. This study indicates the capability of PLGA nanopartcles in enhancing the tumor uptake of letrozole. Copyright 2010 Elsevier B.V. All rights reserved.

Effects of load position and force direction on back muscle loading in one-wheeled wheelbarrow tasks.

PubMed

Chen, Su-Huang; Lee, Yung-Hui; Lin, Chiuhsiang Joe

2015-01-01

Various parameters related to pushing/pulling tasks have been examined yet the effects of changing the load position in one-wheeled wheelbarrow task has not been examined. To explore the effects of load position and force direction on muscle activity during wheelbarrow tasks. Nine participants were recruited to take part in the experiment. Each participant performed 18 trials consisting of 2 force directions (push and pull) and 9 load positions. The dependent variables were EMG of erector spinae and gripping force. ANOVA was used to identify significant differences between force direction and load position in EMG and gripping force data. Results showed that peak EMG was lowest for the left and right erector spinae when the load was positioned farther from the participant. Peak EMG of the bilateral erector spinae increased when the weight was near the participant and on the ipsilateral hand. Based on the EMG results, we suggest that loads be arranged in the anterior part of the bin in order to reduce muscle activity on the spine during the wheelbarrow task. This finding also provides some directions in the improvement and ergonomic redesign of the one-wheeled wheelbarrow.

Predicting physiological capacity of human load carriage - a review.

PubMed

Drain, Jace; Billing, Daniel; Neesham-Smith, Daniel; Aisbett, Brad

2016-01-01

This review article aims to evaluate a proposed maximum acceptable work duration model for load carriage tasks. It is contended that this concept has particular relevance to physically demanding occupations such as military and firefighting. Personnel in these occupations are often required to perform very physically demanding tasks, over varying time periods, often involving load carriage. Previous research has investigated concepts related to physiological workload limits in occupational settings (e.g. industrial). Evidence suggests however, that existing (unloaded) workload guidelines are not appropriate for load carriage tasks. The utility of this model warrants further work to enable prediction of load carriage durations across a range of functional workloads for physically demanding occupations. If the maximum duration for which personnel can physiologically sustain a load carriage task could be accurately predicted, commanders and supervisors could better plan for and manage tasks to ensure operational imperatives were met whilst minimising health risks for their workers. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Distraction and mind-wandering under load.

PubMed

Forster, Sophie

2013-01-01

Attention research over the last several decades has provided rich insights into the determinants of distraction, including distractor characteristics, task features, and individual differences. Load Theory represented a particularly important breakthrough, highlighting the critical role of the level and nature of task-load in determining both the efficiency of distractor rejection and the stage of processing at which this occurs. However, until recently studies of distraction were restricted to those measuring rather specific forms of distraction by external stimuli which I argue that, although intended to be irrelevant, were in fact task-relevant. In daily life, attention may be distracted by a wide range of stimuli, which may often be entirely unrelated to any task being performed, and may include not only external stimuli but also internally generated stimuli such as task-unrelated thoughts. This review outlines recent research examining these more general, entirely task-irrelevant, forms of distraction within the framework of Load Theory. I discuss the relation between different forms of distraction, and the universality of load effects across different distractor types and individuals.

Measuring perceived mental workload in children.

PubMed

Laurie-Rose, Cynthia; Frey, Meredith; Ennis, Aristi; Zamary, Amanda

2014-01-01

Little is known about the mental workload, or psychological costs, associated with information processing tasks in children. We adapted the highly regarded NASA Task Load Index (NASA-TLX) multidimensional workload scale (Hart & Staveland, 1988) to test its efficacy for use with elementary school children. We developed 2 types of tasks, each with 2 levels of demand, to draw differentially on resources from the separate subscales of workload. In Experiment 1, our participants were both typical and school-labeled gifted children recruited from 4th and 5th grades. Results revealed that task type elicited different workload profiles, and task demand directly affected the children's experience of workload. In general, gifted children experienced less workload than typical children. Objective response time and accuracy measures provide evidence for the criterion validity of the workload ratings. In Experiment 2, we applied the same method with 1st- and 2nd-grade children. Findings from Experiment 2 paralleled those of Experiment 1 and support the use of NASA-TLX with even the youngest elementary school children. These findings contribute to the fledgling field of educational ergonomics and attest to the innovative application of workload research. Such research may optimize instructional techniques and identify children at risk for experiencing overload.

Increasing cognitive load attenuates right arm swing in healthy human walking

NASA Astrophysics Data System (ADS)

Killeen, Tim; Easthope, Christopher S.; Filli, Linard; Lőrincz, Lilla; Schrafl-Altermatt, Miriam; Brugger, Peter; Linnebank, Michael; Curt, Armin; Zörner, Björn; Bolliger, Marc

2017-01-01

Human arm swing looks and feels highly automated, yet it is increasingly apparent that higher centres, including the cortex, are involved in many aspects of locomotor control. The addition of a cognitive task increases arm swing asymmetry during walking, but the characteristics and mechanism of this asymmetry are unclear. We hypothesized that this effect is lateralized and a Stroop word-colour naming task-primarily involving left hemisphere structures-would reduce right arm swing only. We recorded gait in 83 healthy subjects aged 18-80 walking normally on a treadmill and while performing a congruent and incongruent Stroop task. The primary measure of arm swing asymmetry-an index based on both three-dimensional wrist trajectories in which positive values indicate proportionally smaller movements on the right-increased significantly under dual-task conditions in those aged 40-59 and further still in the over-60s, driven by reduced right arm flexion. Right arm swing attenuation appears to be the norm in humans performing a locomotor-cognitive dual-task, confirming a prominent role of the brain in locomotor behaviour. Women under 60 are surprisingly resistant to this effect, revealing unexpected gender differences atop the hierarchical chain of locomotor control.

Age differences in high frequency phasic heart rate variability and performance response to increased executive function load in three executive function tasks

PubMed Central

Byrd, Dana L.; Reuther, Erin T.; McNamara, Joseph P. H.; DeLucca, Teri L.; Berg, William K.

2015-01-01

The current study examines similarity or disparity of a frontally mediated physiological response of mental effort among multiple executive functioning tasks between children and adults. Task performance and phasic heart rate variability (HRV) were recorded in children (6 to 10 years old) and adults in an examination of age differences in executive functioning skills during periods of increased demand. Executive load levels were varied by increasing the difficulty levels of three executive functioning tasks: inhibition (IN), working memory (WM), and planning/problem solving (PL). Behavioral performance decreased in all tasks with increased executive demand in both children and adults. Adults’ phasic high frequency HRV was suppressed during the management of increased IN and WM load. Children’s phasic HRV was suppressed during the management of moderate WM load. HRV was not suppressed during either children’s or adults’ increasing load during the PL task. High frequency phasic HRV may be most sensitive to executive function tasks that have a time-response pressure, and simply requiring performance on a self-paced task requiring frontal lobe activation may not be enough to generate HRV responsitivity to increasing demand. PMID:25798113

Concurrent working memory load can facilitate selective attention: evidence for specialized load.

PubMed

Park, Soojin; Kim, Min-Shik; Chun, Marvin M

2007-10-01

Load theory predicts that concurrent working memory load impairs selective attention and increases distractor interference (N. Lavie, A. Hirst, J. W. de Fockert, & E. Viding). Here, the authors present new evidence that the type of concurrent working memory load determines whether load impairs selective attention or not. Working memory load was paired with a same/different matching task that required focusing on targets while ignoring distractors. When working memory items shared the same limited-capacity processing mechanisms with targets in the matching task, distractor interference increased. However, when working memory items shared processing with distractors in the matching task, distractor interference decreased, facilitating target selection. A specialized load account is proposed to describe the dissociable effects of working memory load on selective processing depending on whether the load overlaps with targets or with distractors. (c) 2007 APA

Effects of Peer-Tutor Competences on Learner Cognitive Load and Learning Performance during Knowledge Sharing

ERIC Educational Resources Information Center

Hsiao, Ya-Ping; Brouns, Francis; van Bruggen, Jan; Sloep, Peter B.

2012-01-01

In Learning Networks, learners need to share knowledge with others to build knowledge. In particular, when working on complex tasks, they often need to acquire extra cognitive resources from others to process a high task load. However, without support high task load and organizing knowledge sharing themselves might easily overload learners'…

Mechanical lifting energy consumption in work activities designed by means of the “revised NIOSH lifting equation”

PubMed Central

RANAVOLO, Alberto; VARRECCHIA, Tiwana; RINALDI, Martina; SILVETTI, Alessio; SERRAO, Mariano; CONFORTO, Silvia; DRAICCHIO, Francesco

2017-01-01

The aims of the present work were: to calculate lifting energy consumption (LEC) in work activities designed to have a growing lifting index (LI) by means of revised NIOSH lifting equation; to evaluate the relationship between LEC and forces at the L5-S1 joint. The kinematic and kinetic data of 20 workers were recorded during the execution of lifting tasks in three conditions. We computed kinetic, potential and mechanical energy and the corresponding LEC by considering three different centers of mass of: 1) the load (CoML); 2) the multi-segment upper body model and load together (CoMUpp+L); 3) the whole body and load together (CoMTot). We also estimated compression and shear forces. Results shows that LEC calculated for CoMUpp+L and CoMTot grew significantly with the LI and that all the lifting condition pairs are discriminated. The correlation analysis highlighted a relationship between LEC and forces that determine injuries at the L5-S1 joint. PMID:28781290

Changes in combat task performance under increasing loads in active duty marines.

PubMed

Jaworski, Rebecca L; Jensen, Andrew; Niederberger, Brenda; Congalton, Robert; Kelly, Karen R

2015-03-01

U.S. Marines perform mission tasks under heavy loads which may compromise performance of combat tasks. However, data supporting this performance decrement are limited. The aim of this study was to determine the effects of load on performance of combat-related tasks. Subjects (N=18) ran a modified Maneuver Under Fire ([MANUF], 300 yards [yd] total: two 25-yd sprints, 25-yd crawl, 75-yd casualty drag, 150-yd ammunition can carry, and grenade toss) portion of the U.S. Marine Corps Combat Fitness Test under 4 trial conditions: neat (no load), 15%, 30%, and 45% of body weight, with a shooting task pre- and post-trial. There was a significant increase in total time to completion as a function of load (p<0.0001) with a relationship between load and time (r=0.592, p<0.0001). Pre- to post-MANUF shot accuracy (p=0.005) and precision (p<0.0001) was reduced. Short aerobic performance is significantly impacted by increasing loads. Marksmanship is compromised as a function of fatigue and load. These data suggest that loads of 45% body weight increase time to cover distance and reduce the ability to precisely hit a target. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.

Response terminated displays unload selective attention

PubMed Central

Roper, Zachary J. J.; Vecera, Shaun P.

2013-01-01

Perceptual load theory successfully replaced the early vs. late selection debate by appealing to adaptive control over the efficiency of selective attention. Early selection is observed unless perceptual load (p-Load) is sufficiently low to grant attentional “spill-over” to task-irrelevant stimuli. Many studies exploring load theory have used limited display durations that perhaps impose artificial limits on encoding processes. We extended the exposure duration in a classic p-Load task to alleviate temporal encoding demands that may otherwise tax mnemonic consolidation processes. If the load effect arises from perceptual demands alone, then freeing-up available mnemonic resources by extending the exposure duration should have little effect. The results of Experiment 1 falsify this prediction. We observed a reliable flanker effect under high p-Load, response-terminated displays. Next, we orthogonally manipulated exposure duration and task-relevance. Counter-intuitively, we found that the likelihood of observing the flanker effect under high p-Load resides with the duration of the task-relevant array, not the flanker itself. We propose that stimulus and encoding demands interact to produce the load effect. Our account clarifies how task parameters differentially impinge upon cognitive processes to produce attentional “spill-over” by appealing to visual short-term memory as an additional processing bottleneck when stimuli are briefly presented. PMID:24399983

Response terminated displays unload selective attention.

PubMed

Roper, Zachary J J; Vecera, Shaun P

2013-01-01

Perceptual load theory successfully replaced the early vs. late selection debate by appealing to adaptive control over the efficiency of selective attention. Early selection is observed unless perceptual load (p-Load) is sufficiently low to grant attentional "spill-over" to task-irrelevant stimuli. Many studies exploring load theory have used limited display durations that perhaps impose artificial limits on encoding processes. We extended the exposure duration in a classic p-Load task to alleviate temporal encoding demands that may otherwise tax mnemonic consolidation processes. If the load effect arises from perceptual demands alone, then freeing-up available mnemonic resources by extending the exposure duration should have little effect. The results of Experiment 1 falsify this prediction. We observed a reliable flanker effect under high p-Load, response-terminated displays. Next, we orthogonally manipulated exposure duration and task-relevance. Counter-intuitively, we found that the likelihood of observing the flanker effect under high p-Load resides with the duration of the task-relevant array, not the flanker itself. We propose that stimulus and encoding demands interact to produce the load effect. Our account clarifies how task parameters differentially impinge upon cognitive processes to produce attentional "spill-over" by appealing to visual short-term memory as an additional processing bottleneck when stimuli are briefly presented.

Processing of task-irrelevant emotional faces impacted by implicit sequence learning.

PubMed

Peng, Ming; Cai, Mengfei; Zhou, Renlai

2015-12-02

Attentional load may be increased by task-relevant attention, such as difficulty of task, or task-irrelevant attention, such as an unexpected light-spot in the screen. Several studies have focused on the influence of task-relevant attentional load on task-irrelevant emotion processing. In this study, we used event-related potentials to examine the impact of task-irrelevant attentional load on task-irrelevant expression processing. Eighteen participants identified the color of a word (i.e. the color Stroop task) while a picture of a fearful or a neutral face was shown in the background. The task-irrelevant attentional load was increased by regularly presented congruence trials (congruence between the color and the meaning of the word) in the regular condition because implicit sequence learning was induced. We compared the task-irrelevant expression processing between the regular condition and the random condition (the congruence and incongruence trials were presented randomly). Behaviorally, reaction times for the fearful face condition were faster than the neutral faces condition in the random condition, whereas no significant difference was found in the regular condition. The event-related potential results indicated enhanced positive amplitudes in P2, N2, and P3 components relative to neutral faces in the random condition. In comparison, only P2 differed significantly for the two types of expressions in the regular condition. The study showed that attentional load increased by implicit sequence learning influenced the late processing of task-irrelevant expression.

Sigh rate and respiratory variability during mental load and sustained attention.

PubMed

Vlemincx, Elke; Taelman, Joachim; De Peuter, Steven; Van Diest, Ilse; Van den Bergh, Omer

2011-01-01

Spontaneous breathing consists of substantial correlated variability: Parameters characterizing a breath are correlated with parameters characterizing previous and future breaths. On the basis of dynamic system theory, negative emotion states are predicted to reduce correlated variability whereas sustained attention is expected to reduce total respiratory variability. Both are predicted to evoke sighing. To test this, respiratory variability and sighing were assessed during a baseline, stressful mental arithmetic task, nonstressful sustained attention task, and recovery in between tasks. For respiration rate (excluding sighs), reduced total variability was found during the attention task, whereas correlated variation was reduced during mental load. Sigh rate increased during mental load and during recovery from the attention task. It is concluded that mental load and task-related attention show specific patterns in respiratory variability and sigh rate. Copyright © 2010 Society for Psychophysiological Research.

Executive Resources and Item-Context Binding: Exploring the Influence of Concurrent Inhibition, Updating, and Shifting Tasks on Context Memory

PubMed Central

Nieznański, Marek; Obidziński, Michał; Zyskowska, Emilia; Niedziałkowska, Daria

2015-01-01

Previous research has demonstrated that context memory performance decreases as a result of cognitive load. However, the role of specific executive resources availability has not been specified yet. In a dual-task experiment, participants performed three kinds of concurrent task engaging: inhibition, updating, or shifting operations. In comparison with a no-load single-task condition, a significant decrease in item and context memory was observed, regardless of the kind of executive task. When executive load conditions were compared with non-specific cognitive load conditions, a significant interference effect was observed in the case of the inhibition task. The inhibition process appears to be an aspect of executive control, which relies on the same resource as item-context binding does, especially when binding refers to associations retrieved from long-term memory. PMID:26435761

Spatial working memory load affects counting but not subitizing in enumeration.

PubMed

Shimomura, Tomonari; Kumada, Takatsune

2011-08-01

The present study investigated whether subitizing reflects capacity limitations associated with two types of working memory tasks. Under a dual-task situation, participants performed an enumeration task in conjunction with either a spatial (Experiment 1) or a nonspatial visual (Experiment 2) working memory task. Experiment 1 showed that spatial working memory load affected the slope of a counting function but did not affect subitizing performance or subitizing range. Experiment 2 showed that nonspatial visual working memory load affected neither enumeration efficiency nor subitizing range. Furthermore, in both spatial and nonspatial memory tasks, neither subitizing efficiency nor subitizing range was affected by amount of imposed memory load. In all the experiments, working memory load failed to influence slope, subitizing range, or overall reaction time. These findings suggest that subitizing is performed without either spatial or nonspatial working memory. A possible mechanism of subitizing with independent capacity of working memory is discussed.

Full Scale Evaluation of How Task-Based Overview Displays Impact Operator Workload and Situation Awareness When in Emergency Procedure Space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spielman, Zachary; Hill, Racheal; LeBlanc, Katya

Control room modernization is critical to extending the life of the 99 operating commercial nuclear power plants (NPP) within the United States. However, due to the lack of evidence demonstrating the efficiency and effectiveness of recent candidate technologies, current NPP control rooms operate without the benefit of various newer technologies now available. As nuclear power plants begin to extend their licenses to continue operating for another 20 years, there is increased interest in modernizing the control room and supplementing the existing control boards with advanced technologies. As part of a series of studies investigating the benefits of advanced control roommore » technologies, the researchers conducted an experimental study to observe the effect of Task-Based Overview Displays (TODs) on operator workload and situation awareness (SA) while completing typical operating scenarios. Researchers employed the Situation Awareness Rating Technique (SART) and the NASA Task Load Index (TLX) as construct measures.« less

Astronaut Bone Medical Standards Derived from Finite Element (FE) Models of QCT Scans from Population Studies

NASA Technical Reports Server (NTRS)

Sibonga, J. D.; Feiveson, A. H.

2014-01-01

This work was accomplished in support of the Finite Element [FE] Strength Task Group, NASA Johnson Space Center [JSC], Houston, TX. This group was charged with the task of developing rules for using finite-element [FE] bone-strength measures to construct operating bands for bone health that are relevant to astronauts following exposure to spaceflight. FE modeling is a computational tool used by engineers to estimate the failure loads of complex structures. Recently, some engineers have used this tool to characterize the failure loads of the hip in population studies that also monitored fracture outcomes. A Directed Research Task was authorized in July, 2012 to investigate FE data from these population studies to derive these proposed standards of bone health as a function of age and gender. The proposed standards make use of an FE-based index that integrates multiple contributors to bone strength, an expanded evaluation that is critical after an astronaut is exposed to spaceflight. The current index of bone health used by NASA is the measurement of areal BMD. There was a concern voiced by a research and clinical advisory panel that the sole use of areal BMD would be insufficient to fully evaluate the effects of spaceflight on the hip. Hence, NASA may not have a full understanding of fracture risk, both during and after a mission, and may be poorly estimating in-flight countermeasure efficacy. The FE Strength Task Group - composed of principal investigators of the aforementioned population studies and of FE modelers -donated some of its population QCT data to estimate of hip bone strength by FE modeling for this specific purpose. Consequently, Human Health Countermeasures [HHC] has compiled a dataset of FE hip strengths, generated by a single FE modeling approach, from human subjects (approx.1060) with ages covering the age range of the astronauts. The dataset has been analyzed to generate a set of FE strength cutoffs for the following scenarios: a) Qualify an applicant for astronaut candidacy, b) Qualify an astronaut for a long-duration (LD) mission, c) Qualify a veteran LD astronaut for a second LD mission, and d) Establish a non-permissible, minimum hip strength following a given mission architecture. This abstract will present the FE-based standards accepted by the FE Strength Task Group for its recommendation to HHC in January 2015.

Rethinking the connection between working memory and language impairment.

PubMed

Archibald, Lisa M D; Harder Griebeling, Katherine

2016-05-01

Working memory deficits have been found for children with specific language impairment (SLI) on tasks imposing increasing short-term memory load with or without additional, consistent (and simple) processing load. To examine the processing function of working memory in children with low language (LL) by employing tasks imposing increasing processing loads with constant storage demands individually adjusted based on each participant's short-term memory capacity. School-age groups with LL (n = 17) and typical language with either average (n = 28) or above-average nonverbal intelligence (n = 15) completed complex working memory-span tasks varying processing load while keeping storage demands constant, varying storage demands while keeping processing load constant, simple storage-span tasks, and measures of language and nonverbal intelligence. Teachers completed questionnaires about cognition and learning. Significantly lower scores were found for the LL than either matched group on storage-based tasks, but no group differences were found on the tasks varying processing load. Teachers' ratings of oral expression and mathematics abilities discriminated those who did or did not complete the most challenging cognitive tasks. The results implicate a deficit in the phonological storage but not in the central executive component of working memory for children with LL. Teacher ratings may reveal personality traits related to perseverance of effort in cognitive research. © 2015 Royal College of Speech and Language Therapists.

The impact of cognitive load on delayed recall.

PubMed

Camos, Valérie; Portrat, Sophie

2015-08-01

Recent studies have suggested that long-term retention of items studied in a working memory span task depends on the refreshing of memory items-more specifically, on the number of refreshing opportunities. However, it was previously shown that refreshing depends on the cognitive load of the concurrent task introduced in the working memory span task. Thus, cognitive load should determine the long-term retention of items assessed in a delayed-recall test if such retention relies on refreshing. In two experiments, while the amount of refreshing opportunities remained constant, we varied the cognitive load of the concurrent task by either introducing tasks differing in their attentional demands or varying the pace of the concurrent task. To verify that this effect was related to refreshing and not to any maintenance mechanism, we also manipulated the availability of subvocal rehearsal. Replicating previous results, increasing cognitive load reduced immediate recall. This increase also had a detrimental effect on delayed recall. Conversely, the addition of concurrent articulation reduced immediate but not delayed recall. This study shows that both working and episodic memory traces depend on the cognitive load of the concurrent task, whereas the use of rehearsal affects only working memory performance. These findings add further evidence of the dissociation between subvocal rehearsal and attentional refreshing.

Nicotinic Receptor Gene CHRNA4 Interacts with Processing Load in Attention

PubMed Central

Espeseth, Thomas; Sneve, Markus Handal; Rootwelt, Helge; Laeng, Bruno

2010-01-01

Background Pharmacological studies suggest that cholinergic neurotransmission mediates increases in attentional effort in response to high processing load during attention demanding tasks [1]. Methodology/Principal Findings In the present study we tested whether individual variation in CHRNA4, a gene coding for a subcomponent in α4β2 nicotinic receptors in the human brain, interacted with processing load in multiple-object tracking (MOT) and visual search (VS). We hypothesized that the impact of genotype would increase with greater processing load in the MOT task. Similarly, we predicted that genotype would influence performance under high but not low load in the VS task. Two hundred and two healthy persons (age range = 39–77, Mean = 57.5, SD = 9.4) performed the MOT task in which twelve identical circular objects moved about the display in an independent and unpredictable manner. Two to six objects were designated as targets and the remaining objects were distracters. The same observers also performed a visual search for a target letter (i.e. X or Z) presented together with five non-targets while ignoring centrally presented distracters (i.e. X, Z, or L). Targets differed from non-targets by a unique feature in the low load condition, whereas they shared features in the high load condition. CHRNA4 genotype interacted with processing load in both tasks. Homozygotes for the T allele (N = 62) had better tracking capacity in the MOT task and identified targets faster in the high load trials of the VS task. Conclusion The results support the hypothesis that the cholinergic system modulates attentional effort, and that common genetic variation can be used to study the molecular biology of cognition. PMID:21203548

On the flexibility of grammatical advance planning during sentence production: Effects of cognitive load on multiple lexical access.

PubMed

Wagner, Valentin; Jescheniak, Jörg D; Schriefers, Herbert

2010-03-01

Three picture-word interference experiments addressed the question of whether the scope of grammatical advance planning in sentence production corresponds to some fixed unit or rather is flexible. Subjects produced sentences of different formats under varying amounts of cognitive load. When speakers described 2-object displays with simple sentences of the form "the frog is next to the mug," the 2 nouns were found to be lexically-semantically activated to similar degrees at speech onset, as indexed by similarly sized interference effects from semantic distractors related to either the first or the second noun. When speakers used more complex sentences (including prenominal color adjectives; e.g., "the blue frog is next to the blue mug") much larger interference effects were observed for the first than the second noun, suggesting that the second noun was lexically-semantically activated before speech onset on only a subset of trials. With increased cognitive load, introduced by an additional conceptual decision task and variable utterance formats, the interference effect for the first noun was increased and the interference effect for second noun disappeared, suggesting that the scope of advance planning had been narrowed. By contrast, if cognitive load was induced by a secondary working memory task to be performed during speech planning, the interference effect for both nouns was increased, suggesting that the scope of advance planning had not been affected. In all, the data suggest that the scope of advance planning during grammatical encoding in sentence production is flexible, rather than structurally fixed.

An estimation of finger-tapping rates and load capacities and the effects of various factors.

PubMed

Ekşioğlu, Mahmut; İşeri, Ali

2015-06-01

The aim of this study was to estimate the finger-tapping rates and finger load capacities of eight fingers (excluding thumbs) for a healthy adult population and investigate the effects of various factors on tapping rate. Finger-tapping rate, the total number of finger taps per unit of time, can be used as a design parameter of various products and also as a psychomotor test for evaluating patients with neurologic problems. A 1-min tapping task was performed by 148 participants with maximum volitional tempo for each of eight fingers. For each of the tapping tasks, the participant with the corresponding finger tapped the associated key in the standard position on the home row of a conventional keyboard for touch typing. The index and middle fingers were the fastest fingers for both hands, and little fingers the slowest. All dominant-hand fingers, except little finger, had higher tapping rates than the fastest finger of the nondominant hand. Tapping rate decreased with age and smokers tapped faster than nonsmokers. Tapping duration and exercise had also significant effect on tapping rate. Normative data of tapping rates and load capacities of eight fingers were estimated for the adult population. In designs of psychomotor tests that require the use of tapping rate or finger load capacity data, the effects of finger, age, smoking, and tapping duration need to be taken into account. The findings can be used for ergonomic designs requiring finger-tapping capacity and also as a reference in psychomotor tests. © 2015, Human Factors and Ergonomics Society.

Effects of Additional Low-Pass-Filtered Speech on Listening Effort for Noise-Band-Vocoded Speech in Quiet and in Noise.

PubMed

Pals, Carina; Sarampalis, Anastasios; van Dijk, Mart; Başkent, Deniz

2018-05-11

Residual acoustic hearing in electric-acoustic stimulation (EAS) can benefit cochlear implant (CI) users in increased sound quality, speech intelligibility, and improved tolerance to noise. The goal of this study was to investigate whether the low-pass-filtered acoustic speech in simulated EAS can provide the additional benefit of reducing listening effort for the spectrotemporally degraded signal of noise-band-vocoded speech. Listening effort was investigated using a dual-task paradigm as a behavioral measure, and the NASA Task Load indeX as a subjective self-report measure. The primary task of the dual-task paradigm was identification of sentences presented in three experiments at three fixed intelligibility levels: at near-ceiling, 50%, and 79% intelligibility, achieved by manipulating the presence and level of speech-shaped noise in the background. Listening effort for the primary intelligibility task was reflected in the performance on the secondary, visual response time task. Experimental speech processing conditions included monaural or binaural vocoder, with added low-pass-filtered speech (to simulate EAS) or without (to simulate CI). In Experiment 1, in quiet with intelligibility near-ceiling, additional low-pass-filtered speech reduced listening effort compared with binaural vocoder, in line with our expectations, although not compared with monaural vocoder. In Experiments 2 and 3, for speech in noise, added low-pass-filtered speech allowed the desired intelligibility levels to be reached at less favorable speech-to-noise ratios, as expected. It is interesting that this came without the cost of increased listening effort usually associated with poor speech-to-noise ratios; at 50% intelligibility, even a reduction in listening effort on top of the increased tolerance to noise was observed. The NASA Task Load indeX did not capture these differences. The dual-task results provide partial evidence for a potential decrease in listening effort as a result of adding low-frequency acoustic speech to noise-band-vocoded speech. Whether these findings translate to CI users with residual acoustic hearing will need to be addressed in future research because the quality and frequency range of low-frequency acoustic sound available to listeners with hearing loss may differ from our idealized simulations, and additional factors, such as advanced age and varying etiology, may also play a role.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

[Ocra Method: development of a new procedure for analysis of multiple tasks subject to infrequent rotation].

PubMed

Occhipinti, E; Colombini, Daniela; Occhipinti, M

2008-01-01

In the Ocra methods (Ocra index and Ocra Checklist), when computing the final indices (Ocra index or checklist score), in the case of more than one repetitive task a "traditional" procedure was already proposed, the results of which could be defined as "time-weighted average". This approach appears to be appropriate when considering rotations among tasks that are performed very frequently, for instance almost once every hour (or for shorter periods). However, when rotation among repetitive tasks is less frequent (i.e. once every 1 1/2 or more hours), the "time-weighted average" approach could result in an underestimation of the exposure level (as it practically flattens peaks of high exposures). For those scenarios an alternative approach based on the "most stressful task as minimum" might be more realistic. This latter approach has already been included in the NIOSH approach for multiple sequential lifting tasks and, given the recent availability in the Ocra method of more detailed duration multipliers (practically one different Du(M) for each different step of one hour of duration of the repetitive task), it is now possible to define a particular procedure to compute the complex Ocra Multitask Index (cOCRA) and the complex Checklist Score (cCHESCO) for the analysis of two or more repetitive tasks when rotations are infrequent (rotations every 1 1/2 hours or more). The result of this approach will be at least equal to the index of the most stressful task considered for its individual daily duration and at the most equal to the index of the most stressful task when it is (only theoretically) considered as lasting for the overall daily duration of all examined repetitive tasks. The procedure is based on the following formula: Complex Ocra Multitask Index = Ocra(1(Dum1) + (Delta ocra1xK) where 1,2,3,...,N = repetitive tasks ordered by ocra index values (1 = highest; N = lowest) computed considering respective real duration multipliers (Dum(i)). ocra1 = ocra index of task, considering Dum(1). Dum(i) = duration multiplier for task(i) real duration. Dum(tot) = duration multiplier for total duration of all repetitive tasks. delta ocra1 = highest ocra index among N tasks considering Dum(tot) (ocra(i max)) - ocra index of task1 considering Dum1. K = (ocra(1 max)*FT1) + (ocra(2 max)*FT2) + ... + (ocra (N)*FT(N)) over (ocra(i max)). ocral,Nm(1,N MAX) = index of tasks 1 to Ncons idering Dum,, (tot)7=Fr(i) c tion of Time (values from 0 to 1) of task; wi(i)h respect to the total repetitive time.

Anterior paracingulate and cingulate cortex mediates the effects of cognitive load on speech sound discrimination.

PubMed

Gennari, Silvia P; Millman, Rebecca E; Hymers, Mark; Mattys, Sven L

2018-06-12

Perceiving speech while performing another task is a common challenge in everyday life. How the brain controls resource allocation during speech perception remains poorly understood. Using functional magnetic resonance imaging (fMRI), we investigated the effect of cognitive load on speech perception by examining brain responses of participants performing a phoneme discrimination task and a visual working memory task simultaneously. The visual task involved holding either a single meaningless image in working memory (low cognitive load) or four different images (high cognitive load). Performing the speech task under high load, compared to low load, resulted in decreased activity in pSTG/pMTG and increased activity in visual occipital cortex and two regions known to contribute to visual attention regulation-the superior parietal lobule (SPL) and the paracingulate and anterior cingulate gyrus (PaCG, ACG). Critically, activity in PaCG/ACG was correlated with performance in the visual task and with activity in pSTG/pMTG: Increased activity in PaCG/ACG was observed for individuals with poorer visual performance and with decreased activity in pSTG/pMTG. Moreover, activity in a pSTG/pMTG seed region showed psychophysiological interactions with areas of the PaCG/ACG, with stronger interaction in the high-load than the low-load condition. These findings show that the acoustic analysis of speech is affected by the demands of a concurrent visual task and that the PaCG/ACG plays a role in allocating cognitive resources to concurrent auditory and visual information. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

A Comprehensive Approach for the Ergonomic Evaluation of 13 Emergency and Transport Ventilators.

PubMed

Marjanovic, Nicolas; L'Her, Erwan

2016-05-01

Mechanical ventilation is an important part of emergency medicine and is frequently used for transportation. Human errors during ventilator settings are frequent and may be associated with high morbidity/mortality. The aim of the study was to provide a complete ergonomic evaluation of emergency and transport ventilators, taking into account objective and subjective human-machine interface assessments and individual mental work load. We performed a prospective bench ergonomic evaluation of 13 emergency and transport ventilators, using standardized conditions and a global methodological approach. The study was performed in an evaluation laboratory dedicated to respiratory care, and 12 emergency physicians unfamiliar with the tested devices were included in the evaluation. The ventilators were classified into 3 categories (simple, sophisticated, and ICU-like). Objective chronometric evaluations were conducted considering 9 tasks, and subjective evaluations were performed (ease of use, willingness to use, and user-friendliness of monitoring) using Likert scales. Mental work load evaluation was performed using the NASA Task Load Index scale. Overall task failure rate represented 4% of all attempts. Setting modifications, ventilation mode changes, and powering down durations were different between simple and other emergency and transport ventilator categories (P < .005). There was no difference between ventilator categories for the ease of use and user-friendliness of the monitoring. In contrast, the willingness to use was lower for simple devices, compared with sophisticated and ICU-like emergency and transport ventilators (2.9 ± 1.4 vs 3.9 ± 1.2, P = .002 and 4.3 ± 1, P < .001). No differences were observed between devices regarding the mental work load, except for several specific devices in the sophisticated category. A comprehensive ergonomic evaluation provides valuable information while investigating operational friendliness in emergency and transport ventilators. The choice of a device not only depends on its technical characteristics but should take into account its clinical operational setting and ergonomics in order to decrease mental work load. Sophisticated emergency and transport ventilators should only be used by clinicians who demonstrate expertise in mechanical ventilation. Copyright © 2016 by Daedalus Enterprises.

Ertl and Non-Ertl amputees exhibit functional biomechanical differences during the sit-to-stand task.

PubMed

Ferris, Abbie E; Christiansen, Cory L; Heise, Gary D; Hahn, David; Smith, Jeremy D

2017-05-01

People with transtibial amputation stand ~50times/day. There are two general approaches to transtibial amputation: 1) distal tibia and fibula union using a "bone-bridge" (Ertl), 2) non-union of the tibia and fibula (Non-Ertl). The Ertl technique may improve functional outcomes by increasing the end-bearing ability of the residual limb. We hypothesized individuals with an Ertl would perform a five-time sit-to-stand task faster through greater involvement/end-bearing of the affected limb. Ertl (n=11) and Non-Ertl (n=7) participants sat on a chair with each foot on separate force plates and performed the five-time sit-to-stand task. A symmetry index (intact vs affected limbs) was calculated using peak ground reaction forces. The Ertl group performed the task significantly faster (9.33s (2.66) vs 13.27 (2.83)s). Symmetry index (23.33 (23.83)% Ertl, 36.53 (13.51)% Non-Ertl) indicated the intact limb for both groups produced more force than the affected limb. Ertl affected limb peak ground reaction forces were significantly larger than the Non-Ertl affected limb. Peak knee power and net work of the affected limb were smaller than their respective intact limb for both groups. The Ertl intact limb produced significantly greater peak knee power and net work than the Non-Ertl intact knee. Although loading asymmetries existed between the intact and affected limb of both groups, the Ertl group performed the task ~30% faster. This was driven by greater power and work production of the Ertl intact limb knee. Our results suggest that functional differences exist between the procedures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Auditory temporal preparation induced by rhythmic cues during concurrent auditory working memory tasks.

PubMed

Cutanda, Diana; Correa, Ángel; Sanabria, Daniel

2015-06-01

The present study investigated whether participants can develop temporal preparation driven by auditory isochronous rhythms when concurrently performing an auditory working memory (WM) task. In Experiment 1, participants had to respond to an auditory target presented after a regular or an irregular sequence of auditory stimuli while concurrently performing a Sternberg-type WM task. Results showed that participants responded faster after regular compared with irregular rhythms and that this effect was not affected by WM load; however, the lack of a significant main effect of WM load made it difficult to draw any conclusion regarding the influence of the dual-task manipulation in Experiment 1. In order to enhance dual-task interference, Experiment 2 combined the auditory rhythm procedure with an auditory N-Back task, which required WM updating (monitoring and coding of the information) and was presumably more demanding than the mere rehearsal of the WM task used in Experiment 1. Results now clearly showed dual-task interference effects (slower reaction times [RTs] in the high- vs. the low-load condition). However, such interference did not affect temporal preparation induced by rhythms, with faster RTs after regular than after irregular sequences in the high-load and low-load conditions. These results revealed that secondary tasks demanding memory updating, relative to tasks just demanding rehearsal, produced larger interference effects on overall RTs in the auditory rhythm task. Nevertheless, rhythm regularity exerted a strong temporal preparation effect that survived the interference of the WM task even when both tasks competed for processing resources within the auditory modality. (c) 2015 APA, all rights reserved).

Cognitive task demands, self-control demands and the mental well-being of office workers.

PubMed

Bridger, Robert S; Brasher, Kate

2011-09-01

The cognitive task demands of office workers and the self-control demands of their work roles were measured in a sample of 196 employees in two different office layouts using a self-report questionnaire, which was circulated electronically. Multiple linear regression analysis revealed that both factors were associated with mental well-being, but not with physical well-being, while controlling for exposure to psychosocial stressors. The interaction between cognitive task demands and self-control demands had the strongest association with mental well-being, suggesting that the deleterious effect of one was greater when the other was present. An exploratory analysis revealed that the association was stronger for employees working in a large open-plan office than for those working in smaller offices with more privacy. Frustration of work goals was the cognitive task demand having the strongest negative impact on mental well-being. Methodological limitations and scale psychometrics (particularly the use of the NASA Task Load Index) are discussed. STATEMENT OF RELEVANCE: Modern office work has high mental demands and low physical demands and there is a need to design offices to prevent adverse psychological reactions. It is shown that cognitive task demands interact with self-control demands to degrade mental well-being. The association was stronger in an open-plan office.

Vocal acoustic analysis as a biometric indicator of information processing: implications for neurological and psychiatric disorders.

PubMed

Cohen, Alex S; Dinzeo, Thomas J; Donovan, Neila J; Brown, Caitlin E; Morrison, Sean C

2015-03-30

Vocal expression reflects an integral component of communication that varies considerably within individuals across contexts and is disrupted in a range of neurological and psychiatric disorders. There is reason to suspect that variability in vocal expression reflects, in part, the availability of "on-line" resources (e.g., working memory, attention). Thus, understanding vocal expression is a potentially important biometric index of information processing, not only across but within individuals over time. A first step in this line of research involves establishing a link between vocal expression and information processing systems in healthy adults. The present study employed a dual attention experimental task where participants provided natural speech while simultaneously engaged in a baseline, medium or high nonverbal processing-load task. Objective, automated, and computerized analysis was employed to measure vocal expression in 226 adults. Increased processing load resulted in longer pauses, fewer utterances, greater silence overall and less variability in frequency and intensity levels. These results provide compelling evidence of a link between information processing resources and vocal expression, and provide important information for the development of an automated, inexpensive and uninvasive biometric measure of information processing. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Comparison of risk assessment procedures used in OCRA and ULRA methods

PubMed Central

Roman-Liu, Danuta; Groborz, Anna; Tokarski, Tomasz

2013-01-01

The aim of this study was to analyse the convergence of two methods by comparing exposure and the assessed risk of developing musculoskeletal disorders at 18 repetitive task workstations. The already established occupational repetitive actions (OCRA) and the recently developed upper limb risk assessment (ULRA) produce correlated results (R = 0.84, p = 0.0001). A discussion of the factors that influence the values of the OCRA index and ULRA's repetitive task indicator shows that both similarities and differences in the results produced by the two methods can arise from the concepts that underlie them. The assessment procedure and mathematical calculations that the basic parameters are subjected to are crucial to the results of risk assessment. The way the basic parameters are defined influences the assessment of exposure and risk assessment to a lesser degree. The analysis also proved that not always do great differences in load indicator values result in differences in risk zones. Practitioner Summary: We focused on comparing methods that, even though based on different concepts, serve the same purpose. The results proved that different methods with different assumptions can produce similar assessment of upper limb load; sharp criteria in risk assessment are not the best solution. PMID:24041375

Age-related decline in bottom-up processing and selective attention in the very old.

PubMed

Zhuravleva, Tatyana Y; Alperin, Brittany R; Haring, Anna E; Rentz, Dorene M; Holcomb, Philip J; Daffner, Kirk R

2014-06-01

Previous research demonstrating age-related deficits in selective attention have not included old-old adults, an increasingly important group to study. The current investigation compared event-related potentials in 15 young-old (65-79 years old) and 23 old-old (80-99 years old) subjects during a color-selective attention task. Subjects responded to target letters in a specified color (Attend) while ignoring letters in a different color (Ignore) under both low and high loads. There were no group differences in visual acuity, accuracy, reaction time, or latency of early event-related potential components. The old-old group showed a disruption in bottom-up processing, indexed by a substantially diminished posterior N1 (smaller amplitude). They also demonstrated markedly decreased modulation of bottom-up processing based on selected visual features, indexed by the posterior selection negativity (SN), with similar attenuation under both loads. In contrast, there were no group differences in frontally mediated attentional selection, measured by the anterior selection positivity (SP). There was a robust inverse relationship between the size of the SN and SP (the smaller the SN, the larger the SP), which may represent an anteriorly supported compensatory mechanism. In the absence of a decline in top-down modulation indexed by the SP, the diminished SN may reflect age-related degradation of early bottom-up visual processing in old-old adults.

The Effect of Testosterone Administration and Digit Ratio (2D:4D) on Implicit Preference for Status Goods in Healthy Males

PubMed Central

Wu, Yin; Zilioli, Samuele; Eisenegger, Christoph; Clark, Luke; Li, Hong

2017-01-01

Testosterone has been linked to social status seeking in humans. The present study investigated the effects of testosterone administration on implicit and explicit preferences for status goods in healthy male participants (n = 64), using a double-blind, placebo-controlled, between-subjects design. We also investigated the interactive effect between second-to-fourth digit ratio (2D:4D; i.e., a proximal index of prenatal testosterone) and testosterone treatment on status preferences. Results showed that testosterone administration has no discernable influence on self-reported willingness-to-pay (i.e., the explicit measure) or implicit attitudes towards status goods. Individuals with lower 2D:4D (i.e., more masculine) had more positive attitudes for high-status goods on an Implicit Association Task, and this association was abolished with testosterone administration. These data suggest interactive effects of acute testosterone administration and prenatal testosterone exposure on human social status seeking, and highlight the utility of implicit methods for measuring status-related behavior. PMID:29085287

A cognitive task analysis of information management strategies in a computerized provider order entry environment.

PubMed

Weir, Charlene R; Nebeker, Jonathan J R; Hicken, Bret L; Campo, Rebecca; Drews, Frank; Lebar, Beth

2007-01-01

Computerized Provider Order Entry (CPOE) with electronic documentation, and computerized decision support dramatically changes the information environment of the practicing clinician. Prior work patterns based on paper, verbal exchange, and manual methods are replaced with automated, computerized, and potentially less flexible systems. The objective of this study is to explore the information management strategies that clinicians use in the process of adapting to a CPOE system using cognitive task analysis techniques. Observation and semi-structured interviews were conducted with 88 primary-care clinicians at 10 Veterans Administration Medical Centers. Interviews were taped, transcribed, and extensively analyzed to identify key information management goals, strategies, and tasks. Tasks were aggregated into groups, common components across tasks were clarified, and underlying goals and strategies identified. Nearly half of the identified tasks were not fully supported by the available technology. Six core components of tasks were identified. Four meta-cognitive information management goals emerged: 1) Relevance Screening; 2) Ensuring Accuracy; 3) Minimizing memory load; and 4) Negotiating Responsibility. Strategies used to support these goals are presented. Users develop a wide array of information management strategies that allow them to successfully adapt to new technology. Supporting the ability of users to develop adaptive strategies to support meta-cognitive goals is a key component of a successful system.

Knowledge-based load leveling and task allocation in human-machine systems

NASA Technical Reports Server (NTRS)

Chignell, M. H.; Hancock, P. A.

1986-01-01

Conventional human-machine systems use task allocation policies which are based on the premise of a flexible human operator. This individual is most often required to compensate for and augment the capabilities of the machine. The development of artificial intelligence and improved technologies have allowed for a wider range of task allocation strategies. In response to these issues a Knowledge Based Adaptive Mechanism (KBAM) is proposed for assigning tasks to human and machine in real time, using a load leveling policy. This mechanism employs an online workload assessment and compensation system which is responsive to variations in load through an intelligent interface. This interface consists of a loading strategy reasoner which has access to information about the current status of the human-machine system as well as a database of admissible human/machine loading strategies. Difficulties standing in the way of successful implementation of the load leveling strategy are examined.

Impaired Attentional Disengagement from Stimuli Matching the Contents of Working Memory in Social Anxiety

PubMed Central

Moriya, Jun; Sugiura, Yoshinori

2012-01-01

Although many cognitive models in anxiety propose that an impaired top-down control enhances the processing of task-irrelevant stimuli, few studies have paid attention to task-irrelevant stimuli under a cognitive load task. In the present study, we investigated the effects of the working memory load on attention to task-irrelevant stimuli in trait social anxiety. The results showed that as trait social anxiety increased, participants were unable to disengage from task-irrelevant stimuli identical to the memory cue under low and high working memory loads. Impaired attentional disengagement was positively correlated with trait social anxiety. This impaired attentional disengagement was related to trait social anxiety, but not state anxiety. Our findings suggest that socially anxious people have difficulty in disengaging attention from a task-irrelevant memory cue owing to an impaired top-down control under a working memory load. PMID:23071765

Effect of load carriage on performance of an explosive, anaerobic military task.

PubMed

Treloar, Alison K Laing; Billing, Daniel C

2011-09-01

This study examined the effects of load carriage on performance of an explosive, anaerobic military task. A task-specific assessment requiring five 30-m timed sprints was developed to address this question. Seventeen soldiers (female = 5, male = 12) volunteered to undergo the test under two experimental conditions: unloaded (combat uniform and boots) and loaded (unloaded plus 21.6 kg fighting load, comprising webbing, weapon, helmet, and combat body armor). When loaded, there was a significant increase in the mean 30-m sprint time compared to unloaded (8.2 +/- 1.4 seconds vs. 6.2 +/- 0.8 seconds; p < 0.01). Of the total increase in mean sprint time, 51.7% occurred within the first 5 m. Female sprint times were affected to a larger extent than male (36% vs. 29%, respectively) as a result of the increased load. Fighting load significantly affected soldier mobility when conducting explosive, anaerobic military tasks, particularly among females, and specific physical conditioning should be considered to minimize this effect.

The Interaction of Surface Hydration and Vocal Loading on Voice Measures.

PubMed

Fujiki, Robert Brinton; Chapleau, Abigail; Sundarrajan, Anusha; McKenna, Victoria; Sivasankar, M Preeti

2017-03-01

Vocal loading tasks provide insight regarding the mechanisms underlying healthy laryngeal function. Determining the manner in which the larynx can most efficiently be loaded is a complex task. The goal of this study was to determine if vocal loading could be achieved in 30 minutes by altering phonatory mode. Owing to the fact that surface hydration facilitates efficient vocal fold oscillation, the effects of environmental humidity on vocal loading were also examined. This study also investigated whether the detrimental effects of vocal loading could be attenuated by increasing environmental humidity. Sixteen vocally healthy adults (8 men, 8 women) completed a 30-minute vocal loading task in low and moderate humidity. The order of humidities was counterbalanced across subjects. The vocal loading task consisted of reading with elevated pitch and pressed vocal quality and low pitch and pressed and/or raspy vocal quality in the presence of 65 dB ambient, multi-talker babble noise. Significant effects were observed for (1) cepstral peak prominence on soft sustained phonation at 10th and 80th pitches, (2) perceived phonatory effort, and (3) perceived tiredness ratings. No loading effects were observed for cepstral peak prominence on the rainbow passage, although fundamental frequency on the rainbow passage increased post loading. No main effect was observed for humidity. Following a 30-minute vocal loading task involving altering laryngeal vibratory mode in combination with increased volume. Also, moderate environmental humidity did not significantly attenuate the negative effects of loading. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Who is prone to wander and when? Examining an integrative effect of working memory capacity and mindfulness trait on mind wandering under different task loads.

PubMed

Ju, Yu-Jeng; Lien, Yunn-Wen

2018-06-13

We proposed an integration hypothesis of mind wandering in which the tendency of mind wandering is only related to working memory capacity (WMC) when a self-regulation process is required (i.e., under a high task load); however, this tendency is related to mindfulness regardless of task load. A within-group experiment with 160 participants was conducted. Task load was manipulated as high or low using modified 0-back and 2-back tasks, during which participants' self-caught mind wanderings and the types of mind wandering (aware vs. unaware; intentional vs. unintentional) were measured. The results supported our hypothesis that WMC was negatively associated with mind wandering only in demanding tasks, and mindfulness scores were negatively associated with mind wandering across tasks. Furthermore, we also determined how WMC and the mindfulness trait were related to different types of mind wandering. Theoretical implications were discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

Compensatory Effort Parallels Midbrain Deactivation during Mental Fatigue: An fMRI Study

PubMed Central

Nakagawa, Seishu; Sugiura, Motoaki; Akitsuki, Yuko; Hosseini, S. M. Hadi; Kotozaki, Yuka; Miyauchi, Carlos Makoto; Yomogida, Yukihito; Yokoyama, Ryoichi; Takeuchi, Hikaru; Kawashima, Ryuta

2013-01-01

Fatigue reflects the functioning of our physiological negative feedback system, which prevents us from overworking. When fatigued, however, we often try to suppress this system in an effort to compensate for the resulting deterioration in performance. Previous studies have suggested that the effect of fatigue on neurovascular demand may be influenced by this compensatory effort. The primary goal of the present study was to isolate the effect of compensatory effort on neurovascular demand. Healthy male volunteers participated in a series of visual and auditory divided attention tasks that steadily increased fatigue levels for 2 hours. Functional magnetic resonance imaging scans were performed during the first and last quarter of the study (Pre and Post sessions, respectively). Tasks with low and high attentional load (Low and High conditions, respectively) were administrated in alternating blocks. We assumed that compensatory effort would be greater under the High-attentional-load condition compared with the Low-load condition. The difference was assessed during the two sessions. The effect of compensatory effort on neurovascular demand was evaluated by examining the interaction between load (High vs. Low) and time (Pre vs. Post). Significant fatigue-induced deactivation (i.e., Pre>Post) was observed in the frontal, temporal, occipital, and parietal cortices, in the cerebellum, and in the midbrain in both the High and Low conditions. The interaction was significantly greater in the High than in the Low condition in the midbrain. Neither significant fatigue-induced activation (i.e., Pre[PreE– PostE]) may reflect suppression of the negative feedback system that normally triggers recuperative rest to maintain homeostasis. PMID:23457592

Team performance in networked supervisory control of unmanned air vehicles: effects of automation, working memory, and communication content.

PubMed

McKendrick, Ryan; Shaw, Tyler; de Visser, Ewart; Saqer, Haneen; Kidwell, Brian; Parasuraman, Raja

2014-05-01

Assess team performance within a net-worked supervisory control setting while manipulating automated decision aids and monitoring team communication and working memory ability. Networked systems such as multi-unmanned air vehicle (UAV) supervision have complex properties that make prediction of human-system performance difficult. Automated decision aid can provide valuable information to operators, individual abilities can limit or facilitate team performance, and team communication patterns can alter how effectively individuals work together. We hypothesized that reliable automation, higher working memory capacity, and increased communication rates of task-relevant information would offset performance decrements attributed to high task load. Two-person teams performed a simulated air defense task with two levels of task load and three levels of automated aid reliability. Teams communicated and received decision aid messages via chat window text messages. Task Load x Automation effects were significant across all performance measures. Reliable automation limited the decline in team performance with increasing task load. Average team spatial working memory was a stronger predictor than other measures of team working memory. Frequency of team rapport and enemy location communications positively related to team performance, and word count was negatively related to team performance. Reliable decision aiding mitigated team performance decline during increased task load during multi-UAV supervisory control. Team spatial working memory, communication of spatial information, and team rapport predicted team success. An automated decision aid can improve team performance under high task load. Assessment of spatial working memory and the communication of task-relevant information can help in operator and team selection in supervisory control systems.

Distraction and Mind-Wandering Under Load

PubMed Central

Forster, Sophie

2013-01-01

Attention research over the last several decades has provided rich insights into the determinants of distraction, including distractor characteristics, task features, and individual differences. Load Theory represented a particularly important breakthrough, highlighting the critical role of the level and nature of task-load in determining both the efficiency of distractor rejection and the stage of processing at which this occurs. However, until recently studies of distraction were restricted to those measuring rather specific forms of distraction by external stimuli which I argue that, although intended to be irrelevant, were in fact task-relevant. In daily life, attention may be distracted by a wide range of stimuli, which may often be entirely unrelated to any task being performed, and may include not only external stimuli but also internally generated stimuli such as task-unrelated thoughts. This review outlines recent research examining these more general, entirely task-irrelevant, forms of distraction within the framework of Load Theory. I discuss the relation between different forms of distraction, and the universality of load effects across different distractor types and individuals. PMID:23734138

Harnessing the Wandering Mind: The Role of Perceptual Load

ERIC Educational Resources Information Center

Forster, Sophie; Lavie, Nilli

2009-01-01

Perceptual load is a key determinant of distraction by task-irrelevant stimuli (e.g., Lavie, N. (2005). "Distracted and confused?: Selective attention under load." "Trends in Cognitive Sciences," 9, 75-82). Here we establish the role of perceptual load in determining an internal form of distraction by task-unrelated thoughts (TUTs or…

Selective Impairment of Auditory Selective Attention under Concurrent Cognitive Load

ERIC Educational Resources Information Center

Dittrich, Kerstin; Stahl, Christoph

2012-01-01

Load theory predicts that concurrent cognitive load impairs selective attention. For visual stimuli, it has been shown that this impairment can be selective: Distraction was specifically increased when the stimulus material used in the cognitive load task matches that of the selective attention task. Here, we report four experiments that…

High working memory load impairs the effect of cognitive reappraisal on emotional response: Evidence from an event-related potential study.

PubMed

Gan, Shuzhen; Yang, Jianfeng; Chen, Xuhai; Zhang, Xiuping; Yang, Yufang

2017-02-03

This study investigates how the working memory (WM) load influenced the efficacy of cognitive reappraisal, a frequently used strategy for emotion regulation. In a dual-task paradigm, the participants were required to perform a high-load or a low-load memory task and simultaneously reappraise aversive pictures with a negative or a neutral meaning. In the low-load condition, we found that the amplitude of emotion-enhanced late positive potential (LPP) was significantly decreased by neutral reappraisal compared to negative reappraisal. In the high-load condition, this regulatory effect of reappraisal disappeared. These results suggest that successful reappraisal relies on cognitive resources and WM processes. If the necessary resources involved in reappraisal are over-depleted by a concurrent memory task, the reappraisal effect will be impaired. Moreover, we found that emotion-enhanced LPP was significant in both of the high-load and low-load tasks, which suggests that emotional electrocortical response may not be susceptible to the available resources. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Daily morphine administration increases impulsivity in rats responding under a 5‐choice serial reaction time task

PubMed Central

Maguire, DR; Henson, C

2016-01-01

Background and Purpose Repeated administration of a μ opioid receptor agonist can enhance some forms of impulsivity, such as delay discounting. However, it is unclear whether repeated administration alters motor impulsivity. Experimental Approach We examined the effects of acute administration of morphine and amphetamine prior to and during daily morphine administration in rats responding under a five‐choice serial reaction time task. Rats (n = 5) were trained to detect a brief flash of light presented randomly in one of five response holes; responding in the target hole delivered food, whereas responding in the wrong hole or responding prior to illumination of the target stimulus (premature response) initiated a timeout. Premature responding served as an index of motor impulsivity. Key Results Administered acutely, morphine (0.1–10 mg·kg−1, i.p.) increased omissions and modestly, although not significantly, premature responding without affecting response accuracy; amphetamine (0.1–1.78 mg·kg−1, i.p.) increased premature responding without changing omissions or response accuracy. After 3 weeks of 10 mg·kg−1·day−1 morphine, tolerance developed to its effects on omissions whereas premature responding increased approximately fourfold, compared with baseline. Effects of amphetamine were not significantly affected by daily morphine administration. Conclusions and Implications These data suggest that repeated administration of morphine increased effects of morphine on motor impulsivity, although tolerance developed to other effects, such as omissions. To the extent that impulsivity is a risk factor for drug abuse, repeated administration of μ opioid receptor agonists, for recreational or therapeutic purposes, might increase impulsivity and thus the risk for drug abuse. PMID:26776751

Characteristics of Interruptions During Medication Administration:An Integrative Review of Direct Observational Studies.

PubMed

Schroers, Ginger

2018-06-26

The purpose of this review was to synthesize and summarize data gathered by direct observation of the characteristics of interruptions in the context of nursing medication administration in hospital settings. Interruptions are prevalent during the medication administration process performed by nurses in hospital settings and have been found to be associated with an increase in frequency and severity of nursing medication administration errors. In addition, interruptions decrease task efficiency, leading to longer medication administration completion times. Integrative review. The electronic databases Cumulative Index of Nursing and Allied Health Literature (CINAHL), PubMED, PsyARTICLES, and Google Scholar were searched using the terms "interruptions" AND "medication administration" AND "direct observation". Nine articles met the inclusion criteria. Interruptions are likely to occur at least once during nursing medication administration processes in hospital settings. This finding applies to medication administered to one patient, termed a medication pass, and medication administered to multiple patients, termed a mediation round. Interruptions are most commonly caused by another nurse, staff member, or are self-initiated, and last approximately one minute in length. A raised awareness among staff of the most common sources of interruptions may encourage changes that lead to a decrease in the occurrence of interruptions. In addition, nurse leaders can apply an understanding of the common characteristics of interruptions to guide research, policies, and educational methods aimed at interruption management strategies. The findings from this review can be used to guide the identification and development of targeted interventions and strategies that would have the most substantial impact to reduce and manage interruptions during medication administration. Interruption management strategies have the potential to lead to a decrease in medication errors and an increase in task efficiency. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Load Balancing in Cloud Computing Environment Using Improved Weighted Round Robin Algorithm for Nonpreemptive Dependent Tasks.

PubMed

Devi, D Chitra; Uthariaraj, V Rhymend

2016-01-01

Cloud computing uses the concepts of scheduling and load balancing to migrate tasks to underutilized VMs for effectively sharing the resources. The scheduling of the nonpreemptive tasks in the cloud computing environment is an irrecoverable restraint and hence it has to be assigned to the most appropriate VMs at the initial placement itself. Practically, the arrived jobs consist of multiple interdependent tasks and they may execute the independent tasks in multiple VMs or in the same VM's multiple cores. Also, the jobs arrive during the run time of the server in varying random intervals under various load conditions. The participating heterogeneous resources are managed by allocating the tasks to appropriate resources by static or dynamic scheduling to make the cloud computing more efficient and thus it improves the user satisfaction. Objective of this work is to introduce and evaluate the proposed scheduling and load balancing algorithm by considering the capabilities of each virtual machine (VM), the task length of each requested job, and the interdependency of multiple tasks. Performance of the proposed algorithm is studied by comparing with the existing methods.

Load Balancing in Cloud Computing Environment Using Improved Weighted Round Robin Algorithm for Nonpreemptive Dependent Tasks

PubMed Central

Devi, D. Chitra; Uthariaraj, V. Rhymend

2016-01-01

Cloud computing uses the concepts of scheduling and load balancing to migrate tasks to underutilized VMs for effectively sharing the resources. The scheduling of the nonpreemptive tasks in the cloud computing environment is an irrecoverable restraint and hence it has to be assigned to the most appropriate VMs at the initial placement itself. Practically, the arrived jobs consist of multiple interdependent tasks and they may execute the independent tasks in multiple VMs or in the same VM's multiple cores. Also, the jobs arrive during the run time of the server in varying random intervals under various load conditions. The participating heterogeneous resources are managed by allocating the tasks to appropriate resources by static or dynamic scheduling to make the cloud computing more efficient and thus it improves the user satisfaction. Objective of this work is to introduce and evaluate the proposed scheduling and load balancing algorithm by considering the capabilities of each virtual machine (VM), the task length of each requested job, and the interdependency of multiple tasks. Performance of the proposed algorithm is studied by comparing with the existing methods. PMID:26955656

The effect of auditory memory load on intensity resolution in individuals with Parkinson's disease

NASA Astrophysics Data System (ADS)

Richardson, Kelly C.

Purpose: The purpose of the current study was to investigate the effect of auditory memory load on intensity resolution in individuals with Parkinson's disease (PD) as compared to two groups of listeners without PD. Methods: Nineteen individuals with Parkinson's disease, ten healthy age- and hearing-matched adults, and ten healthy young adults were studied. All listeners participated in two intensity discrimination tasks differing in auditory memory load; a lower memory load, 4IAX task and a higher memory load, ABX task. Intensity discrimination performance was assessed using a bias-free measurement of signal detectability known as d' (d-prime). Listeners further participated in a continuous loudness scaling task where they were instructed to rate the loudness level of each signal intensity using a computerized 150mm visual analogue scale. Results: Group discrimination functions indicated significantly lower intensity discrimination sensitivity (d') across tasks for the individuals with PD, as compared to the older and younger controls. No significant effect of aging on intensity discrimination was observed for either task. All three listeners groups demonstrated significantly lower intensity discrimination sensitivity for the higher auditory memory load, ABX task, compared to the lower auditory memory load, 4IAX task. Furthermore, a significant effect of aging was identified for the loudness scaling condition. The younger controls were found to rate most stimuli along the continuum as significantly louder than the older controls and the individuals with PD. Conclusions: The persons with PD showed evidence of impaired auditory perception for intensity information, as compared to the older and younger controls. The significant effect of aging on loudness perception may indicate peripheral and/or central auditory involvement.

The effects of eye movements on emotional memories: using an objective measure of cognitive load

PubMed Central

van Veen, Suzanne C.; Engelhard, Iris M.; van den Hout, Marcel A.

2016-01-01

Background Eye movement desensitization and reprocessing (EMDR) is an effective treatment for posttraumatic stress disorder. The working memory (WM) theory explains its efficacy: recall of an aversive memory and making eye movements (EM) both produce cognitive load, and competition for the limited WM resources reduces the memory's vividness and emotionality. The present study tested several predictions from WM theory. Objective We hypothesized that 1) recall of an aversive autobiographical memory loads WM compared to no recall, and 2) recall with EM reduces the vividness, emotionality, and cognitive load of recalling the memory more than only recall or only cognitive effort (i.e., recall of an irrelevant memory with EM). Method Undergraduates (N=108) were randomly assigned to one of three conditions: 1) recall relevant memory with EM, 2) recall relevant memory without EM, and 3) recall irrelevant memory with EM. We used a random interval repetition task to measure the cognitive load of recalling the memory. Participants responded to randomly administered beeps, with or without recalling the memory. The degree to which participants slow down during recall provides an index of cognitive load. We measured the cognitive load and self-reported vividness and emotionality before, halfway through (8×24 s), and after (16×24 s) the intervention. Results Reaction times slowed down during memory recall compared to no recall. The recall relevant with EM condition showed a larger decrease in self-reported vividness and emotionality than the control conditions. The cognitive load of recalling the memory also decreased in this condition but not consistently more than in the control conditions. Conclusions Recall of an aversive memory loads WM, but drops in vividness and emotionality do not immediately reduce the cognitive load of recalling the memory. More research is needed to find objective measures that could capture changes in the quality of the memory. Highlights of the article Recall of an aversive autobiographical memory is a cognitive demanding task. The vividness and emotionality of an aversive memory decrease more after recall with eye movements than after only recall or only cognitive effort (i.e., recall of an irrelevant memory with eye movements). The cognitive load of recalling the memory does not immediately reduce after recall with eye movements compared to only recall or only cognitive effort. Intervention duration is positively related to memory effects. PMID:27387845

Attentional capture under high perceptual load.

PubMed

Cosman, Joshua D; Vecera, Shaun P

2010-12-01

Attentional capture by abrupt onsets can be modulated by several factors, including the complexity, or perceptual load, of a scene. We have recently demonstrated that observers are less likely to be captured by abruptly appearing, task-irrelevant stimuli when they perform a search that is high, as opposed to low, in perceptual load (Cosman & Vecera, 2009), consistent with perceptual load theory. However, recent results indicate that onset frequency can influence stimulus-driven capture, with infrequent onsets capturing attention more often than did frequent onsets. Importantly, in our previous task, an abrupt onset was present on every trial, and consequently, attentional capture might have been affected by both onset frequency and perceptual load. In the present experiment, we examined whether onset frequency influences attentional capture under conditions of high perceptual load. When onsets were presented frequently, we replicated our earlier results; attentional capture by onsets was modulated under conditions of high perceptual load. Importantly, however, when onsets were presented infrequently, we observed robust capture effects. These results conflict with a strong form of load theory and, instead, suggest that exposure to the elements of a task (e.g., abrupt onsets) combines with high perceptual load to modulate attentional capture by task-irrelevant information.

Dilution: atheoretical burden or just load? A reply to Tsal and Benoni (2010).

PubMed

Lavie, Nilli; Torralbo, Ana

2010-12-01

Load theory of attention proposes that distractor processing is reduced in tasks with high perceptual load that exhaust attentional capacity within task-relevant processing. In contrast, tasks of low perceptual load leave spare capacity that spills over, resulting in the perception of task-irrelevant, potentially distracting stimuli. Tsal and Benoni (2010) find that distractor response competition effects can be reduced under conditions with a high search set size but low perceptual load (due to a singleton color target). They claim that the usual effect of search set size on distractor processing is not due to attentional load but instead attribute this to lower level visual interference. Here, we propose an account for their findings within load theory. We argue that in tasks of low perceptual load but high set size, an irrelevant distractor competes with the search nontargets for remaining capacity. Thus, distractor processing is reduced under conditions in which the search nontargets receive the spillover of capacity instead of the irrelevant distractor. We report a new experiment testing this prediction. Our new results demonstrate that, when peripheral distractor processing is reduced, it is the search nontargets nearest to the target that are perceived instead. Our findings provide new evidence for the spare capacity spillover hypothesis made by load theory and rule out accounts in terms of lower level visual interference (or mere "dilution") for cases of reduced distractor processing under low load in displays of high set size. We also discuss additional evidence that discounts the viability of Tsal and Benoni's dilution account as an alternative to perceptual load.

Does task-irrelevant colour information create extraneous cognitive load? Evidence from a learning task.

PubMed

Miller, Paul; Hazan-Liran, Batel; Cohen, Danielle

2018-06-01

Previous studies have shown that task-irrelevant information impedes learning by creating extraneous cognitive load. But still open is whether such intrusion reflects a purely semantic phenomenon or whether it also stands for sheer perceptual interference. Using Cognitive Load Theory as a framework, this study aimed to answer this question by examining whether and how task-irrelevant colour information modifies extraneous cognitive load in relation to a new code-learning paradigm. For this purpose, university students were asked to learn, based on an example, associations between colour-related and colour-unrelated words and digits presented in black or in a mismatched ink colour. Evident costs in learning efficacy were found in learning the associations between words and digits for colour-related, but not for colour-unrelated, word stimuli. This suggests that interference by task-irrelevant information in learning stands for a mere semantic conflict. Implications of the findings for extraneous cognitive load on learning efficacy are discussed.

Effects of Task Index Variations On Transfer of Training Criteria. Final Report.

ERIC Educational Resources Information Center

Mirabella, Angelo; Wheaton, George R.

The concluding series of a research program designed to validate a battery of task indexes for use in forecasting the effectiveness of training devices is described. Phase I collated 17 task indexes and applied them to sonar training devices, while in Phase II the 17 index battery was validated, using skill acquisition measures as criteria.…

Concurrent Memory Load Can Make RSVP Search More Efficient

ERIC Educational Resources Information Center

Gil-Gomez de Liano, Beatriz; Botella, Juan

2011-01-01

The detrimental effect of increased memory load on selective attention has been demonstrated in many situations. However, in search tasks over time using RSVP methods, it is not clear how memory load affects attentional processes; no effects as well as beneficial and detrimental effects of memory load have been found in these types of tasks. The…

Stroop proactive control and task conflict are modulated by concurrent working memory load.

PubMed

Kalanthroff, Eyal; Avnit, Amir; Henik, Avishai; Davelaar, Eddy J; Usher, Marius

2015-06-01

Performance on the Stroop task reflects two types of conflict-informational (between the incongruent word and font color) and task (between the contextually relevant color-naming task and the irrelevant, but automatic, word-reading task). According to the dual mechanisms of control theory (DMC; Braver, 2012), variability in Stroop performance can result from variability in the deployment of a proactive task-demand control mechanism. Previous research has shown that when proactive control (PC) is diminished, both increased Stroop interference and a reversed Stroop facilitation (RF) are observed. Although the current DMC model accounts for the former effect, it does not predict the observed RF, which is considered to be behavioral evidence for task conflict in the Stroop task. Here we expanded the DMC model to account for Stroop RF. Assuming that a concurrent working memory (WM) task reduces PC, we predicted both increased interference and an RF. Nineteen participants performed a standard Stroop task combined with a concurrent n-back task, which was aimed at reducing available WM resources, and thus overloading PC. Although the results indicated common Stroop interference and facilitation in the low-load condition (zero-back), in the high-load condition (two-back), both increased Stroop interference and RF were observed, consistent with the model's prediction. These findings indicate that PC is modulated by concurrent WM load and serves as a common control mechanism for both informational and task Stroop conflicts.

Combination of PLGA nanoparticles with mucoadhesive guar-gum films for buccal delivery of antihypertensive peptide.

PubMed

Castro, Pedro M; Baptista, Patrícia; Madureira, Ana Raquel; Sarmento, Bruno; Pintado, Manuela E

2018-05-22

Oral administration of proteins and peptides still is a challenging task to overcome due to low permeability through absorptive epithelia, degradation and metabolism that lead to poor bioavailability. Attempting to overcome such limitations, an antihypertensive peptide derived from whey protein, with KGYGGVSLPEW sequence, was incorporated for the first time into polymeric nanoparticles. An experimental design was followed in order to optimize drug-loading, association efficiency, mean particle size, zeta-potential and polydispersity index of a formulation of poly(lactic-co-glycolic acid) (PLGA) nanoparticles as carriers for bioactive peptides. In sequence, peptide-loaded PLGA nanoparticles were incorporated in a guar-gum film matrix, resulting in a combined delivery system aiming to promote slow release and permeation across buccal epithelium. Neither PLGA nanoparticles, guar-gum films nor the conjugation of PLGA nanoparticles and guar-gum films (GfNp) significantly compromised in vitro TR146 human buccal carcinoma cell line viability after 12 h contact, as assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide reduction assay (MTT). In vitro release assay for developed formulations allowed to conclude that the combination of orodispersible film and nanoparticles granted a slower release of AhP when compared with PLGA or guar-gum films alone or with control. GfNp offered more effective, synergistic, in vitro permeation of TR146 cell multilayer in comparison with guar-gum films or PLGA nanoparticles alone. The combination of PLGA nanoparticles with guar-gum films represent a suitable alternative to conventional per os delivery systems, leading to an increased buccal permeability of carried antihypertensive peptide. Copyright © 2018 Elsevier B.V. All rights reserved.

Affective attention under cognitive load: reduced emotional biases but emergent anxiety-related costs to inhibitory control

PubMed Central

Berggren, Nick; Richards, Anne; Taylor, Joseph; Derakshan, Nazanin

2013-01-01

Trait anxiety is associated with deficits in attentional control, particularly in the ability to inhibit prepotent responses. Here, we investigated this effect while varying the level of cognitive load in a modified antisaccade task that employed emotional facial expressions (neutral, happy, and angry) as targets. Load was manipulated using a secondary auditory task requiring recognition of tones (low load), or recognition of specific tone pitch (high load). Results showed that load increased antisaccade latencies on trials where gaze toward face stimuli should be inhibited. This effect was exacerbated for high anxious individuals. Emotional expression also modulated task performance on antisaccade trials for both high and low anxious participants under low cognitive load, but did not influence performance under high load. Collectively, results (1) suggest that individuals reporting high levels of anxiety are particularly vulnerable to the effects of cognitive load on inhibition, and (2) support recent evidence that loading cognitive processes can reduce emotional influences on attention and cognition. PMID:23717273

Impact of seductive details on the acquisition and transfer of laparoscopic suturing skills: Emotionally interesting or cognitively taxing?

PubMed

Gardner, Aimee K; Clanton, Jesse; Jabbour, Ibrahim I; Scott, Lauren; Scott, Daniel J; Russo, Michael A

2016-09-01

A common strategy to increase learner engagement is to interweave educational material with interesting but slightly tangential tidbits of information (eg, "war stories" and funny anecdotes), known as seductive details. Our objective was to examine the impact of seductive details on initial acquisition and transfer of basic laparoscopic surgical skills. Novices (first- to fourth-year medical students) were randomized into control (N = 47) or seductive details (N = 42) groups. Curricula consisted of a baseline skills assessment (Fundamentals of Laparoscopic Surgery Task 1), instructional video on intracorporeal laparoscopic suturing (Fundamentals of Laparoscopic Surgery Task 5), multiple choice quiz, practice, and assessment on both primary and transfer tasks. Two separate instructional videos were used for Task 5; 20% of the seductive details group's instructional video consisted of seductive details, whereas the control group's video included no seductive details. Participants completed questionnaires of mental workload and task engagement after training. We also conducted a mediation analysis, which is a statistical approach to identify causal paths among a group of variables. Baseline skill scores (control: 112 ± 52; standard deviation: 118 ± 56; 0 = lowest possible score; 600 = highest possible score) and knowledge scores (control: 76 ± 19; standard deviation: 74 ± 16; 0 = lowest possible score; 100 = highest possible score) were similar for both groups. The control group demonstrated better (higher) performance on both the primary (434 ± 193 vs 399 ± 133, P < .05) and transfer (184 ± 74 vs 149 ± 91, P < .05) suturing tasks. Mental workload, as measured by the National Aeronautics and Space Administration-Task Load Index, was more demanding (higher) for the seductive details group (3.8 ± 0.5 vs 3.4 ± 0.7, P < .01; 1 = low workload; 5 = high workload) and was investigated as the possible mechanism by which group assignment impacted performance. Mediational paths using hierarchical regression were significant (P < .05), suggesting that trainees in the seductive details group performed worse because of their increased workload. Our findings suggest that the inclusion of seductive details may be detrimental to the acquisition and transfer of laparoscopic surgical skills due to increased mental workload for trainees. Copyright © 2016 Elsevier Inc. All rights reserved.

Attentional load and sensory competition in human vision: modulation of fMRI responses by load at fixation during task-irrelevant stimulation in the peripheral visual field.

PubMed

Schwartz, Sophie; Vuilleumier, Patrik; Hutton, Chloe; Maravita, Angelo; Dolan, Raymond J; Driver, Jon

2005-06-01

Perceptual suppression of distractors may depend on both endogenous and exogenous factors, such as attentional load of the current task and sensory competition among simultaneous stimuli, respectively. We used functional magnetic resonance imaging (fMRI) to compare these two types of attentional effects and examine how they may interact in the human brain. We varied the attentional load of a visual monitoring task performed on a rapid stream at central fixation without altering the central stimuli themselves, while measuring the impact on fMRI responses to task-irrelevant peripheral checkerboards presented either unilaterally or bilaterally. Activations in visual cortex for irrelevant peripheral stimulation decreased with increasing attentional load at fixation. This relative decrease was present even in V1, but became larger for successive visual areas through to V4. Decreases in activation for contralateral peripheral checkerboards due to higher central load were more pronounced within retinotopic cortex corresponding to 'inner' peripheral locations relatively near the central targets than for more eccentric 'outer' locations, demonstrating a predominant suppression of nearby surround rather than strict 'tunnel vision' during higher task load at central fixation. Contralateral activations for peripheral stimulation in one hemifield were reduced by competition with concurrent stimulation in the other hemifield only in inferior parietal cortex, not in retinotopic areas of occipital visual cortex. In addition, central attentional load interacted with competition due to bilateral versus unilateral peripheral stimuli specifically in posterior parietal and fusiform regions. These results reveal that task-dependent attentional load, and interhemifield stimulus-competition, can produce distinct influences on the neural responses to peripheral visual stimuli within the human visual system. These distinct mechanisms in selective visual processing may be integrated within posterior parietal areas, rather than earlier occipital cortex.

Development of a lumbar EMG-based coactivation index for the assessment of complex dynamic tasks.

PubMed

Le, Peter; Aurand, Alexander; Walter, Benjamin A; Best, Thomas M; Khan, Safdar N; Mendel, Ehud; Marras, William S

2018-03-01

The objective of this study was to develop and test an EMG-based coactivation index and compare it to a coactivation index defined by a biologically assisted lumbar spine model to differentiate between tasks. The purpose was to provide a universal approach to assess coactivation of a multi-muscle system when a computational model is not accessible. The EMG-based index developed utilised anthropometric-defined muscle characteristics driven by torso kinematics and EMG. Muscles were classified as agonists/antagonists based upon 'simulated' moments of the muscles relative to the total 'simulated' moment. Different tasks were used to test the range of the index including lifting, pushing and Valsalva. Results showed that the EMG-based index was comparable to the index defined by a biologically assisted model (r 2  = 0.78). Overall, the EMG-based index provides a universal, usable method to assess the neuromuscular effort associated with coactivation for complex dynamic tasks when the benefit of a biomechanical model is not available. Practitioner Summary: A universal coactivation index for the lumbar spine was developed to assess complex dynamic tasks. This method was validated relative to a model-based index for use when a high-end computational model is not available. Its simplicity allows for fewer inputs and usability for assessment of task ergonomics and rehabilitation.

Thrive or overload? The effect of task complexity on novices' simulation-based learning.

PubMed

Haji, Faizal A; Cheung, Jeffrey J H; Woods, Nicole; Regehr, Glenn; de Ribaupierre, Sandrine; Dubrowski, Adam

2016-09-01

Fidelity is widely viewed as an important element of simulation instructional design based on its purported relationship with transfer of learning. However, higher levels of fidelity may increase task complexity to a point at which novices' cognitive resources become overloaded. In this experiment, we investigate the effects of variations in task complexity on novices' cognitive load and learning during simulation-based procedural skills training. Thirty-eight medical students were randomly assigned to simulation training on a simple or complex lumbar puncture (LP) task. Participants completed four practice trials on this task (skill acquisition). After 10 days of rest, all participants completed one additional trial on their assigned task (retention) and one trial on a 'very complex' simulation designed to be similar to the complex task (transfer). We assessed LP performance and cognitive load on each trial using multiple measures. In both groups, LP performance improved significantly during skill acquisition (p ≤ 0.047, f = 0.29-0.96) and was maintained at retention. The simple task group demonstrated superior performance compared with the complex task group throughout these phases (p ≤ 0.002, d = 1.13-2.31). Cognitive load declined significantly in the simple task group (p < 0.009, f = 0.48-0.76), but not in the complex task group during skill acquisition, and remained lower at retention (p ≤ 0.024, d = 0.78-1.39). Between retention and transfer, LP performance declined and cognitive load increased in the simple task group, whereas both remained stable in the complex task group. At transfer, no group differences were observed in LP performance and cognitive load, except that the simple task group made significantly fewer breaches of sterility (p = 0.023, d = 0.80). Reduced task complexity was associated with superior LP performance and lower cognitive load during skill acquisition and retention, but mixed results on transfer to a more complex task. These results indicate that task complexity is an important factor that may mediate (via cognitive overload) the relationship between instructional design elements (e.g. fidelity) and simulation-based learning outcomes. © 2016 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

Effect of perceptual load on semantic access by speech in children

PubMed Central

Jerger, Susan; Damian, Markus F.; Mills, Candice; Bartlett, James; Tye-Murray, Nancy; Abdi, Hervè

2013-01-01

Purpose To examine whether semantic access by speech requires attention in children. Method Children (N=200) named pictures and ignored distractors on a cross-modal (distractors: auditory-no face) or multi-modal (distractors: auditory-static face and audiovisual-dynamic face) picture word task. The cross-modal had a low load, and the multi-modal had a high load [i.e., respectively naming pictures displayed 1) on a blank screen vs 2) below the talker’s face on his T-shirt]. Semantic content of distractors was manipulated to be related vs unrelated to picture (e.g., picture dog with distractors bear vs cheese). Lavie's (2005) perceptual load model proposes that semantic access is independent of capacity limited attentional resources if irrelevant semantic-content manipulation influences naming times on both tasks despite variations in loads but dependent on attentional resources exhausted by higher load task if irrelevant content influences naming only on cross-modal (low load). Results Irrelevant semantic content affected performance for both tasks in 6- to 9-year-olds, but only on cross-modal in 4–5-year-olds. The addition of visual speech did not influence results on the multi-modal task. Conclusion Younger and older children differ in dependence on attentional resources for semantic access by speech. PMID:22896045

Safety Identifying of Integral Abutment Bridges under Seismic and Thermal Loads

PubMed Central

Easazadeh Far, Narges; Barghian, Majid

2014-01-01

Integral abutment bridges (IABs) have many advantages over conventional bridges in terms of strength and maintenance cost. Due to the integrity of these structures uniform thermal and seismic loads are known important ones on the structure performance. Although all bridge design codes consider temperature and earthquake loads separately in their load combinations for conventional bridges, the thermal load is an “always on” load and, during the occurrence of an earthquake, these two important loads act on bridge simultaneously. Evaluating the safety level of IABs under combination of these loads becomes important. In this paper, the safety of IABs—designed by AASHTO LRFD bridge design code—under combination of thermal and seismic loads is studied. To fulfill this aim, first the target reliability indexes under seismic load have been calculated. Then, these analyses for the same bridge under combination of thermal and seismic loads have been repeated and the obtained reliability indexes are compared with target indexes. It is shown that, for an IAB designed by AASHTO LRFD, the indexes have been reduced under combined effects. So, the target level of safety during its design life is not provided and the code's load combination should be changed. PMID:25405232

Decreased Efficiency of Task-Positive and Task-Negative Networks During Working Memory in Schizophrenia

PubMed Central

Metzak, Paul D.; Riley, Jennifer D.; Wang, Liang; Whitman, Jennifer C.; Ngan, Elton T. C.; Woodward, Todd S.

2012-01-01

Working memory (WM) is one of the most impaired cognitive processes in schizophrenia. Functional magnetic resonance imaging (fMRI) studies in this area have typically found a reduction in information processing efficiency but have focused on the dorsolateral prefrontal cortex. In the current study using the Sternberg Item Recognition Test, we consider networks of regions supporting WM and measure the activation of functionally connected neural networks over different WM load conditions. We used constrained principal component analysis with a finite impulse response basis set to compare the estimated hemodynamic response associated with different WM load condition for 15 healthy control subjects and 15 schizophrenia patients. Three components emerged, reflecting activated (task-positive) and deactivated (task-negative or default-mode) neural networks. Two of the components (with both task-positive and task-negative aspects) were load dependent, were involved in encoding and delay phases (one exclusively encoding and the other both encoding and delay), and both showed evidence for decreased efficiency in patients. The results suggest that WM capacity is reached sooner for schizophrenia patients as the overt levels of WM load increase, to the point that further increases in overt memory load do not increase fMRI activation, and lead to performance impairments. These results are consistent with an account holding that patients show reduced efficiency in task-positive and task-negative networks during WM and also partially support the shifted inverted-U-shaped curve theory of the relationship between WM load and fMRI activation in schizophrenia. PMID:21224491

Dynamic Multiple Work Stealing Strategy for Flexible Load Balancing

NASA Astrophysics Data System (ADS)

Adnan; Sato, Mitsuhisa

Lazy-task creation is an efficient method of overcoming the overhead of the grain-size problem in parallel computing. Work stealing is an effective load balancing strategy for parallel computing. In this paper, we present dynamic work stealing strategies in a lazy-task creation technique for efficient fine-grain task scheduling. The basic idea is to control load balancing granularity depending on the number of task parents in a stack. The dynamic-length strategy of work stealing uses run-time information, which is information on the load of the victim, to determine the number of tasks that a thief is allowed to steal. We compare it with the bottommost first work stealing strategy used in StackThread/MP, and the fixed-length strategy of work stealing, where a thief requests to steal a fixed number of tasks, as well as other multithreaded frameworks such as Cilk and OpenMP task implementations. The experiments show that the dynamic-length strategy of work stealing performs well in irregular workloads such as in UTS benchmarks, as well as in regular workloads such as Fibonacci, Strassen's matrix multiplication, FFT, and Sparse-LU factorization. The dynamic-length strategy works better than the fixed-length strategy because it is more flexible than the latter; this strategy can avoid load imbalance due to overstealing.

Working Memory Load and Reminder Effect on Event-Based Prospective Memory of High- and Low-Achieving Students in Math.

PubMed

Chen, Youzhen; Lian, Rong; Yang, Lixian; Liu, Jianrong; Meng, Yingfang

The effects of working memory (WM) demand and reminders on an event-based prospective memory (PM) task were compared between students with low and high achievement in math. WM load (1- and 2-back tasks) was manipulated as a within-subject factor and reminder (with or without reminder) as a between-subject factor. Results showed that high-achieving students outperformed low-achieving students on all PM and n-back tasks. Use of a reminder improved PM performance and thus reduced prospective interference; the performance of ongoing tasks also improved for all students. Both PM and n-back performances in low WM load were better than in high WM load. High WM load had more influence on low-achieving students than on high-achieving students. Results suggest that low-achieving students in math were weak at PM and influenced more by high WM load. Thus, it is important to train these students to set up an obvious reminder for their PM and improve their WM.

Breakfast high in whey protein or carbohydrates improves coping with workload in healthy subjects.

PubMed

Sihvola, Nora; Korpela, Riitta; Henelius, Andreas; Holm, Anu; Huotilainen, Minna; Müller, Kiti; Poussa, Tuija; Pettersson, Kati; Turpeinen, Anu; Peuhkuri, Katri

2013-11-14

Dietary components may affect brain function and influence behaviour by inducing the synthesis of neurotransmitters. The aim of the present study was to examine the influence of consumption of a whey protein-containing breakfast drink v. a carbohydrate drink v. control on subjective and physiological responses to mental workload in simulated work. In a randomised cross-over design, ten healthy subjects (seven women, median age 26 years, median BMI 23 kg/m(2)) participated in a single-blinded, placebo-controlled study. The subjects performed demanding work-like tasks after having a breakfast drink high in protein (HP) or high in carbohydrate (HC) or a control drink on separate sessions. Subjective states were assessed using the NASA Task Load Index (NASA-TLX), the Karolinska sleepiness scale (KSS) and the modified Profile of Mood States. Heart rate was recorded during task performance. The ratio of plasma tryptophan (Trp) to the sum of the other large neutral amino acids (LNAA) and salivary cortisol were also analysed. The plasma Trp:LNAA ratio was 30 % higher after the test drinks HP (median 0·13 (μmol/l)/(μmol/l)) and HC (median 0·13 (μmol/l)/(μmol/l)) than after the control drink (median 0·10 (μmol/l)/(μmol/l)). The increase in heart rate was smaller after the HP (median 2·7 beats/min) and HC (median 1·9 beats/min) drinks when compared with the control drink (median 7·2 beats/min) during task performance. Subjective sleepiness was reduced more after the HC drink (median KSS - 1·5) than after the control drink (median KSS - 0·5). There were no significant differences between the breakfast types in the NASA-TLX index, cortisol levels or task performance. We conclude that a breakfast drink high in whey protein or carbohydrates may improve coping with mental tasks in healthy subjects.

Effects of working memory contents and perceptual load on distractor processing: When a response-related distractor is held in working memory.

PubMed

Koshino, Hideya

2017-01-01

Working memory and attention are closely related. Recent research has shown that working memory can be viewed as internally directed attention. Working memory can affect attention in at least two ways. One is the effect of working memory load on attention, and the other is the effect of working memory contents on attention. In the present study, an interaction between working memory contents and perceptual load in distractor processing was investigated. Participants performed a perceptual load task in a standard form in one condition (Single task). In the other condition, a response-related distractor was maintained in working memory, rather than presented in the same stimulus display as a target (Dual task). For the Dual task condition, a significant compatibility effect was found under high perceptual load; however, there was no compatibility effect under low perceptual load. These results suggest that the way the contents of working memory affect visual search depends on perceptual load. Copyright © 2016 Elsevier B.V. All rights reserved.

Cognitive load, stress, and disinhibited eating.

PubMed

Lattimore, Paul; Maxwell, Linda

2004-11-01

The impact of cognitive distraction on eating behaviour was examined in restrained and unrestrained eaters. It was predicted that restrained eaters would eat more than unrestrained eaters following high cognitive load when it involves processing of ego-threat information independent of self-reported anxiety. There were 119 female participants randomly allocated to one of four experimental conditions whereby cognitive load and ego threat were manipulated using modified colour-naming Stroop (CNS) tasks. Anxiety ratings were made prior to and following experimental tasks. After performing Stroop tasks, participants consumed snack foods ad libitum. Restrained eaters consumed significantly more food when high cognitive load was ego threatening than when it involved processing and memorisation of colour nouns and consumed significantly more than unrestrained eaters in a high cognitive load ego-threat condition. Posttask anxiety was greater than baseline across all conditions. Task difficulty was greater under high cognitive load than low cognitive load as indicated by Stroop response times. These results indicated that the escape theory of disinhibited eating is conceptually subsumed by a more generalisable limited cognitive capacity model.

Consumption of a high glycemic load but not a high glycemic index diet is marginally associated with oxidative stress in young women.

PubMed

Arikawa, Andrea Y; Jakits, Holly E; Flood, Andrew; Thomas, William; Gross, Myron; Schmitz, Kathryn H; Kurzer, Mindy S

2015-01-01

Research studies have suggested that chronic consumption of high glycemic index foods may lead to chronically high oxidative stress. This is important because oxidative stress is suspected to be an early event in the etiology of many disease processes. We hypothesized that dietary glycemic index and glycemic load were positively associated with oxidative stress assessed by plasma F2-isoprostanes in healthy, premenopausal women (body mass index [BMI] = 24.7 ± 4.8 kg/m(2) and age 25.3 ± 3.5 years, mean ± SD). We measured plasma F2-isoprostanes in 306 healthy premenopausal women at the baseline visit for the Women In Steady Exercise Research study, using gas chromatography-mass spectrometry. Dietary glycemic index and load were calculated from the National Cancer Institute Diet History Questionnaire, and participants were divided into quartiles of dietary glycemic index and of glycemic load. Plasma F2-isoprostanes were compared across quartile groups of dietary glycemic index and glycemic load using linear regression models. Plasma F2-isoprostanes (pg/mL) increased with quartile of glycemic load (test for linear trend, P = .033), and also increased with quartile of glycemic index in participants with BMI ≥ 25 (P = .035) but not in those with BMI <25 (P = .924). After adjustment for BMI, alcohol consumption and total energy intake, both these positive trends remained marginally significant (P = .123 for quartiles of glycemic index and P = .065 for quartiles of glycemic load). Copyright © 2015 Elsevier Inc. All rights reserved.

Brain targeted nanoparticulate drug delivery system of rasagiline via intranasal route.

PubMed

Mittal, Deepti; Md, Shadab; Hasan, Quamrul; Fazil, Mohammad; Ali, Asgar; Baboota, Sanjula; Ali, Javed

2016-01-01

The aim of the present study was to prepare and evaluate a rasagiline-loaded chitosan glutamate nanoparticles (RAS-CG-NPs) by ionic gelation of CG with tripolyphosphate anions (TPP). RAS-loaded CG-NPs were characterized for particle size, size distribution, encapsulation efficiency and in vitro drug release. The mean particles size, polydispersity index (PDI) and encapsulation efficiency was found to be 151.1 ± 10.31, 0.380 ± 0.01 and 96.43 ± 4.23, respectively. Biodistribution of RAS formulations in the brain and blood of mice following intranasal (i.n.) and intravenous (i.v.) administration was performed using HPLC analytical method. The drug concentrations in brain following the i.n. of CG-NPs were found to be significantly higher at all the time points compared to both drug (i.n.) and drug CG-NPs (i.v.). The Cmax (999.25 ng/ml) and AUC (2086.60 ng h/ml) of formulation CG-NPs (i.n) were found to be significantly higher than CG-NPs (i.v.) and RAS solution (i.n.). The direct transport percentage (DTP%) values of RAS-loaded CG-NPs (i.n.) as compared to drug solution (i.n.) increased from 66.27 ± 1.8 to 69.27 ± 2.1%. The results showed significant enhancement of bioavailability in brain, after administration of the RAS-loaded CG-NPs which could be a substantial achievement of direct nose to brain targeting in Parkinson's disease therapy.

Dilution

PubMed Central

Lavie, Nilli; Torralbo, Ana

2010-01-01

Load theory of attention proposes that distractor processing is reduced in tasks with high perceptual load that exhaust attentional capacity within task-relevant processing. In contrast, tasks of low perceptual load leave spare capacity that spills over, resulting in the perception of task-irrelevant, potentially distracting stimuli. Tsal and Benoni (2010) find that distractor response competition effects can be reduced under conditions with a high search set size but low perceptual load (due to a singleton color target). They claim that the usual effect of search set size on distractor processing is not due to attentional load but instead attribute this to lower level visual interference. Here, we propose an account for their findings within load theory. We argue that in tasks of low perceptual load but high set size, an irrelevant distractor competes with the search nontargets for remaining capacity. Thus, distractor processing is reduced under conditions in which the search nontargets receive the spillover of capacity instead of the irrelevant distractor. We report a new experiment testing this prediction. Our new results demonstrate that, when peripheral distractor processing is reduced, it is the search nontargets nearest to the target that are perceived instead. Our findings provide new evidence for the spare capacity spillover hypothesis made by load theory and rule out accounts in terms of lower level visual interference (or mere “dilution”) for cases of reduced distractor processing under low load in displays of high set size. We also discuss additional evidence that discounts the viability of Tsal and Benoni's dilution account as an alternative to perceptual load. PMID:21133554

Cognitive load and task condition in event- and time-based prospective memory: an experimental investigation.

PubMed

Khan, Azizuddin; Sharma, Narendra K; Dixit, Shikha

2008-09-01

Prospective memory is memory for the realization of delayed intention. Researchers distinguish 2 kinds of prospective memory: event- and time-based (G. O. Einstein & M. A. McDaniel, 1990). Taking that distinction into account, the present authors explored participants' comparative performance under event- and time-based tasks. In an experimental study of 80 participants, the authors investigated the roles of cognitive load and task condition in prospective memory. Cognitive load (low vs. high) and task condition (event- vs. time-based task) were the independent variables. Accuracy in prospective memory was the dependent variable. Results showed significant differential effects under event- and time-based tasks. However, the effect of cognitive load was more detrimental in time-based prospective memory. Results also revealed that time monitoring is critical in successful performance of time estimation and so in time-based prospective memory. Similarly, participants' better performance on the event-based prospective memory task showed that they acted on the basis of environment cues. Event-based prospective memory was environmentally cued; time-based prospective memory required self-initiation.

The psychometrics of mental workload: multiple measures are sensitive but divergent.

PubMed

Matthews, Gerald; Reinerman-Jones, Lauren E; Barber, Daniel J; Abich, Julian

2015-02-01

A study was run to test the sensitivity of multiple workload indices to the differing cognitive demands of four military monitoring task scenarios and to investigate relationships between indices. Various psychophysiological indices of mental workload exhibit sensitivity to task factors. However, the psychometric properties of multiple indices, including the extent to which they intercorrelate, have not been adequately investigated. One hundred fifty participants performed in four task scenarios based on a simulation of unmanned ground vehicle operation. Scenarios required threat detection and/or change detection. Both single- and dual-task scenarios were used. Workload metrics for each scenario were derived from the electroencephalogram (EEG), electrocardiogram, transcranial Doppler sonography, functional near infrared, and eye tracking. Subjective workload was also assessed. Several metrics showed sensitivity to the differing demands of the four scenarios. Eye fixation duration and the Task Load Index metric derived from EEG were diagnostic of single-versus dual-task performance. Several other metrics differentiated the two single tasks but were less effective in differentiating single- from dual-task performance. Psychometric analyses confirmed the reliability of individual metrics but failed to identify any general workload factor. An analysis of difference scores between low- and high-workload conditions suggested an effort factor defined by heart rate variability and frontal cortex oxygenation. General workload is not well defined psychometrically, although various individual metrics may satisfy conventional criteria for workload assessment. Practitioners should exercise caution in using multiple metrics that may not correspond well, especially at the level of the individual operator.

What is the relationship between mental workload factors and cognitive load types?

PubMed

Galy, Edith; Cariou, Magali; Mélan, Claudine

2012-03-01

The present study tested the hypothesis of an additive interaction between intrinsic, extraneous and germane cognitive load, by manipulating factors of mental workload assumed to have a specific effect on either type of cognitive load. The study of cognitive load factors and their interaction is essential if we are to improve workers' wellbeing and safety at work. High cognitive load requires the individual to allocate extra resources to entering information. It is thought that this demand for extra resources may reduce processing efficiency and performance. The present study tested the effects of three factors thought to act on either cognitive load type, i.e. task difficulty, time pressure and alertness in a working memory task. Results revealed additive effects of task difficulty and time pressure, and a modulation by alertness on behavioral, subjective and psychophysiological workload measures. Mental overload can be the result of a combination of task-related components, but its occurrence may also depend on subject-related characteristics, including alertness. Solutions designed to reduce incidents and accidents at work should consider work organization in addition to task constraints in so far that both these factors may interfere with mental workload. Copyright © 2011 Elsevier B.V. All rights reserved.

Missing a trick: Auditory load modulates conscious awareness in audition.

PubMed

Fairnie, Jake; Moore, Brian C J; Remington, Anna

2016-07-01

In the visual domain there is considerable evidence supporting the Load Theory of Attention and Cognitive Control, which holds that conscious perception of background stimuli depends on the level of perceptual load involved in a primary task. However, literature on the applicability of this theory to the auditory domain is limited and, in many cases, inconsistent. Here we present a novel "auditory search task" that allows systematic investigation of the impact of auditory load on auditory conscious perception. An array of simultaneous, spatially separated sounds was presented to participants. On half the trials, a critical stimulus was presented concurrently with the array. Participants were asked to detect which of 2 possible targets was present in the array (primary task), and whether the critical stimulus was present or absent (secondary task). Increasing the auditory load of the primary task (raising the number of sounds in the array) consistently reduced the ability to detect the critical stimulus. This indicates that, at least in certain situations, load theory applies in the auditory domain. The implications of this finding are discussed both with respect to our understanding of typical audition and for populations with altered auditory processing. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Worst case estimation of homology design by convex analysis

NASA Technical Reports Server (NTRS)

Yoshikawa, N.; Elishakoff, Isaac; Nakagiri, S.

1998-01-01

The methodology of homology design is investigated for optimum design of advanced structures. for which the achievement of delicate tasks by the aid of active control system is demanded. The proposed formulation of homology design, based on the finite element sensitivity analysis, necessarily requires the specification of external loadings. The formulation to evaluate the worst case for homology design caused by uncertain fluctuation of loadings is presented by means of the convex model of uncertainty, in which uncertainty variables are assigned to discretized nodal forces and are confined within a conceivable convex hull given as a hyperellipse. The worst case of the distortion from objective homologous deformation is estimated by the Lagrange multiplier method searching the point to maximize the error index on the boundary of the convex hull. The validity of the proposed method is demonstrated in a numerical example using the eleven-bar truss structure.

[Effects of the verbal loading on laterality difference in visual field (author's transl)].

PubMed

Kawai, M

1980-02-01

In connection with the Kinsbourne's attention-model, the relation between the level of hemisphere sharing of loading task and the visual-laterality difference was examined under verbal loading conditions. The subjects were 13 (8 male and 5 female) right-handed college students. The loading tasks in Exp. I were the "same-different" judgment of Japanese hiragana alphabets and of triliteral hiragana words, and "true-false" judgment of short statements. In Exp. II, a procedure to eliminate configurational matching of the letters was followed. The results of the two experiments suggest that the visual-laterality effect occurs only when the level of hemisphere sharing of the loading task exceeds a certain lower bound.

Task allocation in a distributed computing system

NASA Technical Reports Server (NTRS)

Seward, Walter D.

1987-01-01

A conceptual framework is examined for task allocation in distributed systems. Application and computing system parameters critical to task allocation decision processes are discussed. Task allocation techniques are addressed which focus on achieving a balance in the load distribution among the system's processors. Equalization of computing load among the processing elements is the goal. Examples of system performance are presented for specific applications. Both static and dynamic allocation of tasks are considered and system performance is evaluated using different task allocation methodologies.

Describing the interplay between anxiety and cognition: From impaired performance under low cognitive load to reduced anxiety under high load

PubMed Central

Vytal, Katherine; Cornwell, Brian; Arkin, Nicole; Grillon, Christian

2012-01-01

Anxiety impairs the ability to think and concentrate, suggesting that the interaction between emotion and cognition may elucidate the debilitating nature of pathological anxiety. Using a verbal n-back task that parametrically modulated cognitive load, we explored the effect of experimentally-induced anxiety on task performance and the startle reflex. Findings suggest there is a crucial inflection point between moderate and high cognitive load, where resources shift from anxious apprehension to focus on task demands. Specifically, we demonstrate that anxiety impairs performance under low-load, but is reduced when subjects engage in a difficult task that occupies executive resources. We propose a two-component model of anxiety that describes a cognitive mechanism behind performance impairment and an automatic response that supports sustained anxiety-potentiated startle. Implications for therapeutic interventions and emotional pathology are discussed. PMID:22332819

The own-age bias in face memory is unrelated to differences in attention--evidence from event-related potentials.

PubMed

Neumann, Markus F; End, Albert; Luttmann, Stefanie; Schweinberger, Stefan R; Wiese, Holger

2015-03-01

Participants are more accurate at remembering faces from their own relative to a different age group (the own-age bias, or OAB). A recent socio-cognitive account has suggested that differential allocation of attention to old versus young faces underlies this phenomenon. Critically, empirical evidence for a direct relationship between attention to own- versus other-age faces and the OAB in memory is lacking. To fill this gap, we tested the roles of attention in three different experimental paradigms, and additionally analyzed event-related brain potentials (ERPs). In Experiment 1, we compared the learning of old and young faces during focused versus divided attention, but revealed similar OABs in subsequent memory for both attention conditions. Similarly, manipulating attention during learning did not differentially affect the ERPs elicited by young versus old faces. In Experiment 2, we examined the repetition effects from task-irrelevant old and young faces presented under varying attentional loads on the N250r ERP component as an index of face recognition. Independent of load, the N250r effects were comparable for both age categories. Finally, in Experiment 3 we measured the N2pc as an index of attentional selection of old versus young target faces in a visual search task. The N2pc was not significantly different for the young versus the old target search conditions, suggesting similar orientations of attention to either face age group. Overall, we propose that the OAB in memory is largely unrelated to early attentional processes. Our findings therefore contrast with the predictions from socio-cognitive accounts on own-group biases in recognition memory, and are more easily reconciled with expertise-based models.

Effects of Planning on Task Load, Knowledge, and Tool Preference: A Comparison of Two Tools

ERIC Educational Resources Information Center

Bonestroo, Wilco J.; de Jong, Ton

2012-01-01

Self-regulated learners are expected to plan their own learning. Because planning is a complex task, it is not self-evident that all learners can perform this task successfully. In this study, we examined the effects of two planning support tools on the quality of created plans, planning behavior, task load, and acquired knowledge. Sixty-five…

Embedded interruptions and task complexity influence schema-related cognitive load progression in an abstract learning task.

PubMed

Wirzberger, Maria; Esmaeili Bijarsari, Shirin; Rey, Günter Daniel

2017-09-01

Cognitive processes related to schema acquisition comprise an essential source of demands in learning situations. Since the related amount of cognitive load is supposed to change over time, plausible temporal models of load progression based on different theoretical backgrounds are inspected in this study. A total of 116 student participants completed a basal symbol sequence learning task, which provided insights into underlying cognitive dynamics. Two levels of task complexity were determined by the amount of elements within the symbol sequence. In addition, interruptions due to an embedded secondary task occurred at five predefined stages over the task. Within the resulting 2x5-factorial mixed between-within design, the continuous monitoring of efficiency in learning performance enabled assumptions on relevant resource investment. From the obtained results, a nonlinear change of learning efficiency over time seems most plausible in terms of cognitive load progression. Moreover, different effects of the induced interruptions show up in conditions of task complexity, which indicate the activation of distinct cognitive mechanisms related to structural aspects of the task. Findings are discussed in the light of evidence from research on memory and information processing. Copyright © 2017 Elsevier B.V. All rights reserved.

Racial differences in knee osteoarthritis pain: potential contribution of occupational and household tasks.

PubMed

Allen, Kelli D; Chen, Jiu-Chiuan; Callahan, Leigh F; Golightly, Yvonne M; Helmick, Charles G; Renner, Jordan B; Schwartz, Todd A; Jordan, Joanne M

2012-02-01

We examined whether occupational and household tasks contributed to differences in pain between African Americans and whites with radiographic knee osteoarthritis (OA). Participants from the Johnston County Osteoarthritis Project self-reported the frequency (often/always vs never/seldom/sometimes) of performing 9 occupational tasks involving lower extremity joint loading at their longest job (N = 868) and current job (N = 273), as well as 8 household tasks ever performed (N = 811) and currently being performed (N = 767). The associations of the numbers of occupational or household tasks with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale were first examined in simple linear regression models. If significantly associated with greater pain, each of these was included in adjusted linear regression models to examine whether the association of race with pain remained statistically significant. African Americans reported significantly greater WOMAC pain scores than whites. Exposures to more occupational tasks at the longest job and the current job were associated with greater WOMAC pain scores (p < 0.01). The association of race with greater pain scores remained statistically significant when controlling for occupational tasks at the longest job, but was reduced by 26% and no longer significant when controlling for the number of current occupational tasks. Exposures to an increasing number of household tasks were associated with lower pain scores and were not further analyzed. Current performance of physically demanding occupational tasks contributed to racial differences in pain severity among individuals with knee OA. Better workplace policies to accommodate OA-related limitations may help to reduce racial differences in pain.

Retrospective attention enhances visual working memory in the young but not the old: an ERP study

PubMed Central

Duarte, Audrey; Hearons, Patricia; Jiang, Yashu; Delvin, Mary Courtney; Newsome, Rachel N.; Verhaeghen, Paul

2013-01-01

Behavioral evidence from the young suggests spatial cues that orient attention toward task relevant items in visual working memory (VWM) enhance memory capacity. Whether older adults can also use retrospective cues (“retro-cues”) to enhance VWM capacity is unknown. In the current event-related potential (ERP) study, young and old adults performed a VWM task in which spatially informative retro-cues were presented during maintenance. Young but not older adults’ VWM capacity benefitted from retro-cueing. The contralateral delay activity (CDA) ERP index of VWM maintenance was attenuated after the retro-cue, which effectively reduced the impact of memory load. CDA amplitudes were reduced prior to retro-cue onset in the old only. Despite a preserved ability to delete items from VWM, older adults may be less able to use retrospective attention to enhance memory capacity when expectancy of impending spatial cues disrupts effective VWM maintenance. PMID:23445536

Individual differences in working memory and reasoning-remembering relationships in solving class-inclusion problems.

PubMed

Howe, M L; Rabinowitz, F M; Powell, T L

1998-09-01

In the present experiment, we evaluated the effects of individual differences in reading span and variation in memory demands on class-inclusion performance. One hundred twenty college students whose reading spans ranged from low to medium to high (as indexed by a computerized version of the Daneman and Carpenter [1980] reading-span task) solved 48 class-inclusion problems. Half of the subjects had the solution information available when the problems were presented; the other half performed a detection task between solution information and problem presentation. The results from both standard statistical analyses and from a mathematical model indicated that differences in reading span and memory load had predictable, similar effects. Specifically, the sophistication of reasoning strategies declined when memory demands increased or when reading spans decreased. Surprisingly, these effects were primarily additive. The results were interpreted in terms of global resource models and findings from the developmental literature.

The effects of individual differences, prior experience and cognitive load on the transfer of dynamic decision-making performance.

PubMed

Nicholson, Brad; O'Hare, David

2014-01-01

Situational awareness is recognised as an important factor in the performance of individuals and teams in dynamic decision-making (DDM) environments (Salmon et al. 2014 ). The present study was designed to investigate whether the scores on the WOMBAT™ Situational Awareness and Stress Tolerance Test (Roscoe and North 1980 ) would predict the transfer of DDM performance from training under different levels of cognitive load to a novel situation. Participants practised a simulated firefighting task under either low or high conditions of cognitive load and then performed a (transfer) test in an alternative firefighting environment under an intermediate level of cognitive load. WOMBAT™ test scores were a better predictor of DDM performance than scores on the Raven Matrices. Participants with high WOMBAT™ scores performed better regardless of their training condition. Participants with recent gaming experience who practised under low cognitive load showed better practice phase performance but worse transfer performance than those who practised under high cognitive load. The relationship between task experience, situational awareness ability, cognitive load and the transfer of dynamic decision-making (DDM) performance was investigated. Results showed that the WOMBAT™ test predicted transfer of DDM performance regardless of task cognitive load. The effects of cognitive load on performance varied according to previous task-relevant experience.

Stimulus recognition occurs under high perceptual load: Evidence from correlated flankers.

PubMed

Cosman, Joshua D; Mordkoff, J Toby; Vecera, Shaun P

2016-12-01

A dominant account of selective attention, perceptual load theory, proposes that when attentional resources are exhausted, task-irrelevant information receives little attention and goes unrecognized. However, the flanker effect-typically used to assay stimulus identification-requires an arbitrary mapping between a stimulus and a response. We looked for failures of flanker identification by using a more-sensitive measure that does not require arbitrary stimulus-response mappings: the correlated flankers effect. We found that flanking items that were task-irrelevant but that correlated with target identity produced a correlated flanker effect. Participants were faster on trials in which the irrelevant flanker had previously correlated with the target than when it did not. Of importance, this correlated flanker effect appeared regardless of perceptual load, occurring even in high-load displays that should have abolished flanker identification. Findings from a standard flanker task replicated the basic perceptual load effect, with flankers not affecting response times under high perceptual load. Our results indicate that task-irrelevant information can be processed to a high level (identification), even under high perceptual load. This challenges a strong account of high perceptual load effects that hypothesizes complete failures of stimulus identification under high perceptual load. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

The Influence of Load and Speed on Individuals' Movement Behavior.

PubMed

Frost, David M; Beach, Tyson A C; Callaghan, Jack P; McGill, Stuart M

2015-09-01

Because individuals' movement patterns have been linked to their risk of future injury, movement evaluations have become a topic of interest. However, if individuals adapt their movement behavior in response to the demands of a task, the utility of evaluations comprising only low-demand activities could have limited application with regard to the prediction of future injury. This investigation examined the impact of load and speed on individuals' movement behavior. Fifty-two firefighters performed 5 low-demand (i.e., light load, low movement speed) whole-body tasks (i.e., lift, squat, lunge, push, and pull). Each task was then modified by increasing the speed, external load, or speed and load. Select measures of motion were used to characterize the performance of each task, and comparisons were made between conditions. The participants adapted their movement behavior in response to the external demands of a task (64 and 70% of all the variables were influenced [p ≤ 0.05] by changing the load and speed, respectively), but in a manner unique to the task and type of demand. The participants exhibited greater spine and frontal plane knee motion in response to an increase in speed when compared with increasing loads. However, there were a large number of movement strategies exhibited by individual firefighters that differed from the group's response. The data obtained here imply that individuals may not be physically prepared to perform safely or effectively when a task's demands are elevated simply because they exhibit the ability to perform a low-demand activity with competence. Therefore, movement screens comprising only low-demand activities may not adequately reflect an individual's capacity, or their risk of injury, and could adversely affect any recommendations that are made for training or job performance.

Voluntary task switching under load: contribution of top-down and bottom-up factors in goal-directed behavior.

PubMed

Demanet, Jelle; Verbruggen, Frederick; Liefooghe, Baptist; Vandierendonck, André

2010-06-01

The present study investigated the relative contribution of bottom-up and top-down control to task selection in the voluntary task-switching (VTS) procedure. In order to manipulate the efficiency of top-down control, a concurrent working memory load was imposed during VTS. In three experiments, bottom-up factors, such as stimulus repetitions, repetition of irrelevant information, and stimulus-task associations, were introduced in order to investigate their influence on task selection. We observed that the tendency to repeat tasks was stronger under load, suggesting that top-down control counteracts the automatic tendency to repeat tasks. The results also indicated that task selection can be guided by several elements in the environment, but that only the influence of stimulus repetitions depends on the efficiency of top-down control. The theoretical implications of these findings are discussed within the interplay between top-down and bottom-up control that underlies the voluntary selection of tasks.

Load-related brain activation predicts spatial working memory performance in youth aged 9–12 and is associated with executive function at earlier ages

PubMed Central

Huang, Anna S.; Klein, Daniel N.; Leung, Hoi-Chung

2015-01-01

Spatial working memory is a central cognitive process that matures through adolescence in conjunction with major changes in brain function and anatomy. Here we focused on late childhood and early adolescence to more closely examine the neural correlates of performance variability during this important transition period. Using a modified spatial 1-back task with two memory load conditions in an fMRI study, we examined the relationship between load-dependent neural responses and task performance in a sample of 39 youth aged 9–12 years. Our data revealed that between-subject differences in task performance was predicted by load-dependent deactivation in default network regions, including the ventral anterior cingulate cortex (vACC) and posterior cingulate cortex (PCC). Although load-dependent increases in activation in prefrontal and posterior parietal regions were only weakly correlated with performance, increased prefrontal-parietal coupling was associated with better performance. Furthermore, behavioral measures of executive function from as early as age 3 predicted current load-dependent deactivation in vACC and PCC. These findings suggest that both task positive and task negative brain activation during spatial working memory contributed to successful task performance in late childhood/early adolescence. This may serve as a good model for studying executive control deficits in developmental disorders. PMID:26562059

Load-related brain activation predicts spatial working memory performance in youth aged 9-12 and is associated with executive function at earlier ages.

PubMed

Huang, Anna S; Klein, Daniel N; Leung, Hoi-Chung

2016-02-01

Spatial working memory is a central cognitive process that matures through adolescence in conjunction with major changes in brain function and anatomy. Here we focused on late childhood and early adolescence to more closely examine the neural correlates of performance variability during this important transition period. Using a modified spatial 1-back task with two memory load conditions in an fMRI study, we examined the relationship between load-dependent neural responses and task performance in a sample of 39 youth aged 9-12 years. Our data revealed that between-subject differences in task performance was predicted by load-dependent deactivation in default network regions, including the ventral anterior cingulate cortex (vACC) and posterior cingulate cortex (PCC). Although load-dependent increases in activation in prefrontal and posterior parietal regions were only weakly correlated with performance, increased prefrontal-parietal coupling was associated with better performance. Furthermore, behavioral measures of executive function from as early as age 3 predicted current load-dependent deactivation in vACC and PCC. These findings suggest that both task positive and task negative brain activation during spatial working memory contributed to successful task performance in late childhood/early adolescence. This may serve as a good model for studying executive control deficits in developmental disorders. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Measuring cognitive load: performance, mental effort and simulation task complexity.

PubMed

Haji, Faizal A; Rojas, David; Childs, Ruth; de Ribaupierre, Sandrine; Dubrowski, Adam

2015-08-01

Interest in applying cognitive load theory in health care simulation is growing. This line of inquiry requires measures that are sensitive to changes in cognitive load arising from different instructional designs. Recently, mental effort ratings and secondary task performance have shown promise as measures of cognitive load in health care simulation. We investigate the sensitivity of these measures to predicted differences in intrinsic load arising from variations in task complexity and learner expertise during simulation-based surgical skills training. We randomly assigned 28 novice medical students to simulation training on a simple or complex surgical knot-tying task. Participants completed 13 practice trials, interspersed with computer-based video instruction. On trials 1, 5, 9 and 13, knot-tying performance was assessed using time and movement efficiency measures, and cognitive load was assessed using subjective rating of mental effort (SRME) and simple reaction time (SRT) on a vibrotactile stimulus-monitoring secondary task. Significant improvements in knot-tying performance (F(1.04,24.95)  = 41.1, p < 0.001 for movements; F(1.04,25.90)  = 49.9, p < 0.001 for time) and reduced cognitive load (F(2.3,58.5)  = 57.7, p < 0.001 for SRME; F(1.8,47.3)  = 10.5, p < 0.001 for SRT) were observed in both groups during training. The simple-task group demonstrated superior knot tying (F(1,24)  = 5.2, p = 0.031 for movements; F(1,24)  = 6.5, p = 0.017 for time) and a faster decline in SRME over the first five trials (F(1,26)  = 6.45, p = 0.017) compared with their peers. Although SRT followed a similar pattern, group differences were not statistically significant. Both secondary task performance and mental effort ratings are sensitive to changes in intrinsic load among novices engaged in simulation-based learning. These measures can be used to track cognitive load during skills training. Mental effort ratings are also sensitive to small differences in intrinsic load arising from variations in the physical complexity of a simulation task. The complementary nature of these subjective and objective measures suggests their combined use is advantageous in simulation instructional design research. © 2015 John Wiley & Sons Ltd.

Effects of automation and task load on task switching during human supervision of multiple semi-autonomous robots in a dynamic environment.

PubMed

Squire, P N; Parasuraman, R

2010-08-01

The present study assessed the impact of task load and level of automation (LOA) on task switching in participants supervising a team of four or eight semi-autonomous robots in a simulated 'capture the flag' game. Participants were faster to perform the same task than when they chose to switch between different task actions. They also took longer to switch between different tasks when supervising the robots at a high compared to a low LOA. Task load, as manipulated by the number of robots to be supervised, did not influence switch costs. The results suggest that the design of future unmanned vehicle (UV) systems should take into account not simply how many UVs an operator can supervise, but also the impact of LOA and task operations on task switching during supervision of multiple UVs. The findings of this study are relevant for the ergonomics practice of UV systems. This research extends the cognitive theory of task switching to inform the design of UV systems and results show that switching between UVs is an important factor to consider.

[Information value of "additional tasks" method to evaluate pilot's work load].

PubMed

Gorbunov, V V

2005-01-01

"Additional task" method was used to evaluate pilot's work load in prolonged flight. Calculated through durations of latent periods of motor responses, quantitative criterion of work load is more informative for objective evaluation of pilot's involvement in his piloting functions rather than of other registered parameters.

The Role of Perceptual Load in Inattentional Blindness

ERIC Educational Resources Information Center

Cartwright-Finch, Ula; Lavie, Nilli

2007-01-01

Perceptual load theory offers a resolution to the long-standing early vs. late selection debate over whether task-irrelevant stimuli are perceived, suggesting that irrelevant perception depends upon the perceptual load of task-relevant processing. However, previous evidence for this theory has relied on RTs and neuroimaging. Here we tested the…

Studying the effects of dietary body weight-adjusted acute tryptophan depletion on punishment-related behavioral inhibition.

PubMed

Gaber, Tilman J; Dingerkus, Vita L S; Crockett, Molly J; Bubenzer-Busch, Sarah; Helmbold, Katrin; Sánchez, Cristina L; Dahmen, Brigitte; Herpertz-Dahlmann, Beate; Zepf, Florian D

2015-01-01

Alterations in serotonergic (5-HT) neurotransmission are thought to play a decisive role in affective disorders and impulse control. This study aims to reproduce and extend previous findings on the effects of acute tryptophan depletion (ATD) and subsequently diminished central 5-HT synthesis in a reinforced categorization task using a refined body weight-adjusted depletion protocol. Twenty-four young healthy adults (12 females, mean age [SD]=25.3 [2.1] years) were subjected to a double-blind within-subject crossover design. Each subject was administered both an ATD challenge and a balanced amino acid load (BAL) in two separate sessions in randomized order. Punishment-related behavioral inhibition was assessed using a forced choice go/no-go task that incorporated a variable payoff schedule. Administration of ATD resulted in significant reductions in TRP measured in peripheral blood samples, indicating reductions of TRP influx across the blood-brain barrier and related brain 5-HT synthesis. Overall accuracy and response time performance were improved after ATD administration. The ability to adjust behavioral responses to aversive outcome magnitudes and behavioral adjustments following error contingent punishment remained intact after decreased brain 5-HT synthesis. A previously observed dissociation effect of ATD on punishment-induced inhibition was not observed. Our results suggest that neurodietary challenges with ATD Moja-De have no detrimental effects on task performance and punishment-related inhibition in healthy adults.

Quantification of baseline pupillary response and task-evoked pupillary response during constant and incremental task load.

PubMed

Mosaly, Prithima R; Mazur, Lukasz M; Marks, Lawrence B

2017-10-01

The methods employed to quantify the baseline pupil size and task-evoked pupillary response (TEPR) may affect the overall study results. To test this hypothesis, the objective of this study was to assess variability in baseline pupil size and TEPR during two basic working memory tasks: constant load of 3-letters memorisation-recall (10 trials), and incremental load memorisation-recall (two trials of each load level), using two commonly used methods (1) change from trail/load specific baseline, (2) change from constant baseline. Results indicated that there was a significant shift in baseline between the trails for constant load, and between the load levels for incremental load. The TEPR was independent of shifts in baseline using method 1 only for constant load, and method 2 only for higher levels of incremental load condition. These important findings suggest that the assessment of both the baseline and methods to quantify TEPR are critical in ergonomics application, especially in studies with small number of trials per subject per condition. Practitioner Summary: Quantification of TEPR can be affected by shifts in baseline pupil size that are most likely affected by non-cognitive factors when other external factors are kept constant. Therefore, quantification methods employed to compute both baseline and TEPR are critical in understanding the information processing of humans in practical ergonomics settings.

Mechanical lifting energy consumption in work activities designed by means of the "revised NIOSH lifting equation".

PubMed

Ranavolo, Alberto; Varrecchia, Tiwana; Rinaldi, Martina; Silvetti, Alessio; Serrao, Mariano; Conforto, Silvia; Draicchio, Francesco

2017-10-07

The aims of the present work were: to calculate lifting energy consumption (LEC) in work activities designed to have a growing lifting index (LI) by means of revised NIOSH lifting equation; to evaluate the relationship between LEC and forces at the L 5 -S 1 joint. The kinematic and kinetic data of 20 workers were recorded during the execution of lifting tasks in three conditions. We computed kinetic, potential and mechanical energy and the corresponding LEC by considering three different centers of mass of: 1) the load (CoM L ); 2) the multi-segment upper body model and load together (CoM Upp+L ); 3) the whole body and load together (CoM Tot ). We also estimated compression and shear forces. Results shows that LEC calculated for CoM Upp+L and CoM Tot grew significantly with the LI and that all the lifting condition pairs are discriminated. The correlation analysis highlighted a relationship between LEC and forces that determine injuries at the L 5 -S 1 joint.

A Cognitive Task Analysis of Information Management Strategies in a Computerized Provider Order Entry Environment

PubMed Central

Weir, Charlene R.; Nebeker, Jonathan J.R.; Hicken, Bret L.; Campo, Rebecca; Drews, Frank; LeBar, Beth

2007-01-01

Objective Computerized Provider Order Entry (CPOE) with electronic documentation, and computerized decision support dramatically changes the information environment of the practicing clinician. Prior work patterns based on paper, verbal exchange, and manual methods are replaced with automated, computerized, and potentially less flexible systems. The objective of this study is to explore the information management strategies that clinicians use in the process of adapting to a CPOE system using cognitive task analysis techniques. Design Observation and semi-structured interviews were conducted with 88 primary-care clinicians at 10 Veterans Administration Medical Centers. Measurements Interviews were taped, transcribed, and extensively analyzed to identify key information management goals, strategies, and tasks. Tasks were aggregated into groups, common components across tasks were clarified, and underlying goals and strategies identified. Results Nearly half of the identified tasks were not fully supported by the available technology. Six core components of tasks were identified. Four meta-cognitive information management goals emerged: 1) Relevance Screening; 2) Ensuring Accuracy; 3) Minimizing memory load; and 4) Negotiating Responsibility. Strategies used to support these goals are presented. Conclusion Users develop a wide array of information management strategies that allow them to successfully adapt to new technology. Supporting the ability of users to develop adaptive strategies to support meta-cognitive goals is a key component of a successful system. PMID:17068345

Visual scanning behavior and mental workload in aircraft pilots

NASA Technical Reports Server (NTRS)

Tole, J. R.; Harris, R. L., Sr.; Stephens, A. T.; Ephrath, A. R.

1982-01-01

This paper describes an experimental paradigm and a set of preliminary results which demonstrate a relationship between the level of performance on a skilled man-machine control task, the skill of the operator, the level of mental difficulty induced by an additional task imposed on the basic control task, and visual scanning performance. During a constant, simulated piloting task, visual scanning of instruments was found to vary as a function of the level of difficulty of a verbal loading task. The average dwell time of each fixation on the pilot's primary instrument increased as a function of the loading. The scanning behavior was also a function of the estimated skill level of the pilots, with novices being affected by the loading task much more than experts. The results suggest that visual scanning of instruments in a controlled task may be an indicator of both workload and skill.

Accurate expectancies diminish perceptual distraction during visual search

PubMed Central

Sy, Jocelyn L.; Guerin, Scott A.; Stegman, Anna; Giesbrecht, Barry

2014-01-01

The load theory of visual attention proposes that efficient selective perceptual processing of task-relevant information during search is determined automatically by the perceptual demands of the display. If the perceptual demands required to process task-relevant information are not enough to consume all available capacity, then the remaining capacity automatically and exhaustively “spills-over” to task-irrelevant information. The spill-over of perceptual processing capacity increases the likelihood that task-irrelevant information will impair performance. In two visual search experiments, we tested the automaticity of the allocation of perceptual processing resources by measuring the extent to which the processing of task-irrelevant distracting stimuli was modulated by both perceptual load and top-down expectations using behavior, functional magnetic resonance imaging, and electrophysiology. Expectations were generated using a trial-by-trial cue that provided information about the likely load of the upcoming visual search task. When the cues were valid, behavioral interference was eliminated and the influence of load on frontoparietal and visual cortical responses was attenuated relative to when the cues were invalid. In conditions in which task-irrelevant information interfered with performance and modulated visual activity, individual differences in mean blood oxygenation level dependent responses measured from the left intraparietal sulcus were negatively correlated with individual differences in the severity of distraction. These results are consistent with the interpretation that a top-down biasing mechanism interacts with perceptual load to support filtering of task-irrelevant information. PMID:24904374

Proximal arm kinematics affect grip force-load force coordination

PubMed Central

Vermillion, Billy C.; Lum, Peter S.

2015-01-01

During object manipulation, grip force is coordinated with load force, which is primarily determined by object kinematics. Proximal arm kinematics may affect grip force control, as proximal segment motion could affect control of distal hand muscles via biomechanical and/or neural pathways. The aim of this study was to investigate the impact of proximal kinematics on grip force modulation during object manipulation. Fifteen subjects performed three vertical lifting tasks that involved distinct proximal kinematics (elbow/shoulder), but resulted in similar end-point (hand) trajectories. While temporal coordination of grip and load forces remained similar across the tasks, proximal kinematics significantly affected the grip force-to-load force ratio (P = 0.042), intrinsic finger muscle activation (P = 0.045), and flexor-extensor ratio (P < 0.001). Biomechanical coupling between extrinsic hand muscles and the elbow joint cannot fully explain the observed changes, as task-related changes in intrinsic hand muscle activation were greater than in extrinsic hand muscles. Rather, between-task variation in grip force (highest during task 3) appears to contrast to that in shoulder joint velocity/acceleration (lowest during task 3). These results suggest that complex neural coupling between the distal and proximal upper extremity musculature may affect grip force control during movements, also indicated by task-related changes in intermuscular coherence of muscle pairs, including intrinsic finger muscles. Furthermore, examination of the fingertip force showed that the human motor system may attempt to reduce variability in task-relevant motor output (grip force-to-load force ratio), while allowing larger fluctuations in output less relevant to task goal (shear force-to-grip force ratio). PMID:26289460

Eye Gaze and Aging: Selective and Combined Effects of Working Memory and Inhibitory Control.

PubMed

Crawford, Trevor J; Smith, Eleanor S; Berry, Donna M

2017-01-01

Eye-tracking is increasingly studied as a cognitive and biological marker for the early signs of neuropsychological and psychiatric disorders. However, in order to make further progress, a more comprehensive understanding of the age-related effects on eye-tracking is essential. The antisaccade task requires participants to make saccadic eye movements away from a prepotent stimulus. Speculation on the cause of the observed age-related differences in the antisaccade task largely centers around two sources of cognitive dysfunction: inhibitory control (IC) and working memory (WM). The IC account views cognitive slowing and task errors as a direct result of the decline of inhibitory cognitive mechanisms. An alternative theory considers that a deterioration of WM is the cause of these age-related effects on behavior. The current study assessed IC and WM processes underpinning saccadic eye movements in young and older participants. This was achieved with three experimental conditions that systematically varied the extent to which WM and IC were taxed in the antisaccade task: a memory-guided task was used to explore the effect of increasing the WM load; a Go/No-Go task was used to explore the effect of increasing the inhibitory load; a 'standard' antisaccade task retained the standard WM and inhibitory loads. Saccadic eye movements were also examined in a control condition: the standard prosaccade task where the load of WM and IC were minimal or absent. Saccade latencies, error rates and the spatial accuracy of saccades of older participants were compared to the same measures in healthy young controls across the conditions. The results revealed that aging is associated with changes in both IC and WM. Increasing the inhibitory load was associated with increased reaction times in the older group, while the increased WM load and the inhibitory load contributed to an increase in the antisaccade errors. These results reveal that aging is associated with changes in both IC and WM.

A multidisciplinary approach of workload assessment in real-job situations: investigation in the field of aerospace activities.

PubMed

Mélan, Claudine; Cascino, Nadine

2014-01-01

The present contribution presents two field studies combining tools and methods from cognitive psychology and from occupational psychology in order to perform a thorough investigation of workload in employees. Cognitive load theory proposes to distinguish different load categories of working memory, in a context of instruction. Intrinsic load is inherent to the task, extraneous load refers to components of a learning environment that may be modified to reduce total load, and germane load enables schemas construction and thus efficient learning. We showed previously that this theoretical framework may be successfully extended to working memory tasks in non-instructional designs. Other theoretical models, issued from the field of occupational psychology, account for an individual's perception of work demands or requirements in the context of different psychosocial features of the (work) environment. Combining these approaches is difficult as workload assessment by job-perception questionnaires explore an individual's overall job-perception over a large time-period, whereas cognitive load investigations in working memory tasks are typically performed within short time-periods. We proposed an original methodology enabling investigation of workload and load factors in a comparable time-frame. We report two field studies investigating workload on different shift-phases and between work-shifts, with two custom-made tools. The first one enabled workload assessment by manipulating intrinsic load (task difficulty) and extraneous load (time pressure) in a working-memory task. The second tool was a questionnaire based on the theoretical concepts of work-demands, control, and psychosocial support. Two additional dimensions suspected to contribute to job-perception, i.e., work-family conflicts and availability of human and technical resources were also explored. Results of workload assessments were discussed in light of operators' alertness and job-performance.

Involuntary autobiographical memories are relatively more often reported during high cognitive load tasks.

PubMed

Barzykowski, Krystian; Niedźwieńska, Agnieszka

2018-01-01

Recent studies on involuntary autobiographical memories (IAMs) in daily life have shown that they are most frequently reported during daily routines (e.g. while ironing). Such studies have suggested that reporting IAMs may be influenced by the level of the ongoing task demands and availability of cognitive resources. In two studies, we investigated the effects of cognitive load on reporting IAMs. To examine the presumed cognitive load dependency of IAMs, we utilised an often-employed experimental paradigm (Schlagman & Kvavilashvili, 2008) to elicit IAMs under conditions that differed in cognitive load. When performing a vigilance task, participants had to interrupt the task each time they experienced any spontaneous mental contents and write them down. We manipulated the level of cognitive load by either instructing (cognitive load group) or not instructing (control group) participants to perform an additional demanding task. We compared the groups on the number of IAMs and other mental contents (non-IAM contents) recorded, as well as on the frequency of IAMs that was calculated as a proportion of IAMs in all mental contents reported by the participant. We expected that if reporting IAMs depends on the level of cognitive demands, then we should observe lower frequency of IAMs in the cognitive load group compared to the control group. Consistently across studies, we observed a lower number of IAMs and non-IAM contents in the cognitive load group. However, IAMs unexpectedly constituted a higher percentage of all mental contents when participants were cognitively loaded. Further implications of the cognitive load effects for IAMs research and experimental methodology are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

A multidisciplinary approach of workload assessment in real-job situations: investigation in the field of aerospace activities

PubMed Central

Mélan, Claudine; Cascino, Nadine

2014-01-01

The present contribution presents two field studies combining tools and methods from cognitive psychology and from occupational psychology in order to perform a thorough investigation of workload in employees. Cognitive load theory proposes to distinguish different load categories of working memory, in a context of instruction. Intrinsic load is inherent to the task, extraneous load refers to components of a learning environment that may be modified to reduce total load, and germane load enables schemas construction and thus efficient learning. We showed previously that this theoretical framework may be successfully extended to working memory tasks in non-instructional designs. Other theoretical models, issued from the field of occupational psychology, account for an individual’s perception of work demands or requirements in the context of different psychosocial features of the (work) environment. Combining these approaches is difficult as workload assessment by job-perception questionnaires explore an individual’s overall job-perception over a large time-period, whereas cognitive load investigations in working memory tasks are typically performed within short time-periods. We proposed an original methodology enabling investigation of workload and load factors in a comparable time-frame. We report two field studies investigating workload on different shift-phases and between work-shifts, with two custom-made tools. The first one enabled workload assessment by manipulating intrinsic load (task difficulty) and extraneous load (time pressure) in a working-memory task. The second tool was a questionnaire based on the theoretical concepts of work-demands, control, and psychosocial support. Two additional dimensions suspected to contribute to job-perception, i.e., work–family conflicts and availability of human and technical resources were also explored. Results of workload assessments were discussed in light of operators’ alertness and job-performance. PMID:25232346

Working memory load and distraction: dissociable effects of visual maintenance and cognitive control.

PubMed

Konstantinou, Nikos; Beal, Eleanor; King, Jean-Remi; Lavie, Nilli

2014-10-01

We establish a new dissociation between the roles of working memory (WM) cognitive control and visual maintenance in selective attention as measured by the efficiency of distractor rejection. The extent to which focused selective attention can prevent distraction has been shown to critically depend on the level and type of load involved in the task. High perceptual load that consumes perceptual capacity leads to reduced distractor processing, whereas high WM load that reduces WM ability to exert priority-based executive cognitive control over the task results in increased distractor processing (e.g., Lavie, Trends in Cognitive Sciences, 9(2), 75-82, 2005). WM also serves to maintain task-relevant visual representations, and such visual maintenance is known to recruit the same sensory cortices as those involved in perception (e.g., Pasternak & Greenlee, Nature Reviews Neuroscience, 6(2), 97-107, 2005). These findings led us to hypothesize that loading WM with visual maintenance would reduce visual capacity involved in perception, thus resulting in reduced distractor processing-similar to perceptual load and opposite to WM cognitive control load. Distractor processing was assessed in a response competition task, presented during the memory interval (or during encoding; Experiment 1a) of a WM task. Loading visual maintenance or encoding by increased set size for a memory sample of shapes, colors, and locations led to reduced distractor response competition effects. In contrast, loading WM cognitive control with verbal rehearsal of a random letter set led to increased distractor effects. These findings confirm load theory predictions and provide a novel functional distinction between the roles of WM maintenance and cognitive control in selective attention.

Visual short-term memory load reduces retinotopic cortex response to contrast.

PubMed

Konstantinou, Nikos; Bahrami, Bahador; Rees, Geraint; Lavie, Nilli

2012-11-01

Load Theory of attention suggests that high perceptual load in a task leads to reduced sensory visual cortex response to task-unrelated stimuli resulting in "load-induced blindness" [e.g., Lavie, N. Attention, distraction and cognitive control under load. Current Directions in Psychological Science, 19, 143-148, 2010; Lavie, N. Distracted and confused?: Selective attention under load. Trends in Cognitive Sciences, 9, 75-82, 2005]. Consideration of the findings that visual STM (VSTM) involves sensory recruitment [e.g., Pasternak, T., & Greenlee, M. Working memory in primate sensory systems. Nature Reviews Neuroscience, 6, 97-107, 2005] within Load Theory led us to a new hypothesis regarding the effects of VSTM load on visual processing. If VSTM load draws on sensory visual capacity, then similar to perceptual load, high VSTM load should also reduce visual cortex response to incoming stimuli leading to a failure to detect them. We tested this hypothesis with fMRI and behavioral measures of visual detection sensitivity. Participants detected the presence of a contrast increment during the maintenance delay in a VSTM task requiring maintenance of color and position. Increased VSTM load (manipulated by increased set size) led to reduced retinotopic visual cortex (V1-V3) responses to contrast as well as reduced detection sensitivity, as we predicted. Additional visual detection experiments established a clear tradeoff between the amount of information maintained in VSTM and detection sensitivity, while ruling out alternative accounts for the effects of VSTM load in terms of differential spatial allocation strategies or task difficulty. These findings extend Load Theory to demonstrate a new form of competitive interactions between early visual cortex processing and visual representations held in memory under load and provide a novel line of support for the sensory recruitment hypothesis of VSTM.

Application of the central composite design to optimize the preparation of novel micelles of harmine.

PubMed

Bei, Yong-Yan; Zhou, Xiao-Feng; You, Ben-Gang; Yuan, Zhi-Qiang; Chen, Wei-Liang; Xia, Peng; Liu, Yang; Jin, Yong; Hu, Xiao-Juan; Zhu, Qiao-Ling; Zhang, Chun-Ge; Zhang, Xue-Nong; Zhang, Liang

2013-01-01

Lactose-palmitoyl-trimethyl-chitosan (Lac-TPCS), a novel amphipathic self-assembled polymer, was synthesized for administration of insoluble drugs to reduce their adverse effects. The central composite design was used to study the preparation technique of harmine (HM)-loaded self-assembled micelles based on Lac-TPCS (Lac-TPCS/HM). Three preparation methods and single factors were screened, including solvent type, HM amount, hydration volume, and temperature. The optimal preparation technique was identified after investigating the influence of two independent factors, namely, HM amount and hydration volume, on four indexes, ie, encapsulation efficiency (EE), drug-loading amount (LD), particle size, and polydispersity index (PDI). Analysis of variance showed a high coefficient of determination of 0.916 to 0.994, thus ensuring a satisfactory adjustment of the predicted prescription. The maximum predicted values of the optimal prescription were 91.62%, 14.20%, 183.3 nm, and 0.214 for EE, LD, size, and PDI, respectively, when HM amount was 1.8 mg and hydration volume was 9.6 mL. HM-loaded micelles were successfully characterized by Fourier-transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and a fluorescence-quenching experiment. Sustained release of Lac-TPCS/HM reached 65.3% in 72 hours at pH 7.4, while free HM released about 99.7% under the same conditions.

A functional MRI study of working memory task in euthymic bipolar disorder: evidence for task-specific dysfunction.

PubMed

Monks, Paul J; Thompson, Jill M; Bullmore, Edward T; Suckling, John; Brammer, Michael J; Williams, Steve C R; Simmons, Andrew; Giles, Nicola; Lloyd, Adrian J; Harrison, C Louise; Seal, Marc; Murray, Robin M; Ferrier, I Nicol; Young, Allan H; Curtis, Vivienne A

2004-12-01

Even when euthymic bipolar disorder patients can have persistent deficits in working memory, but the neural basis of this deficit remains unclear. We undertook an functional magnetic resonance imaging investigation of euthymic bipolar disorder patients performing two working memory paradigms; the two-back and Sternberg tasks, selected to examine the central executive and the phonological loop respectively. We hypothesized that neuronal dysfunction would be specific to the network underlying the executive rather than the phonological loop component of working memory. Twelve right-handed euthymic bipolar I males receiving lithium carbonate monotherapy were matched with 12 controls. The two-back task comprised a single working memory load contrasted with baseline vigilance condition. The Sternberg paradigm used a parametric design incorporating variable working memory load with fixed delay between presentation of an array of items to be remembered and a target item. Functional activation data were acquired during performance of the tasks and were analysed to produce brain activation maps representing significant group differences in activation (ANOVA). Load-response curves were derived from the Sternberg task data set. There were no significant between-group differences (t-test) in performance of the two-back task, or in 2 x 5 group by memory load ANOVA for the performance data from Sternberg task. In the two-back task, compared with controls bipolar disorder patients showed reductions in bilateral frontal, temporal and parietal activation, and increased activations with the left precentral, right medial frontal and left supramarginal gyri. No between-group differences were observed in the Sternberg task at any working memory load. Our findings support the notion that, in euthymic bipolar disorder, failure to engage fronto-executive function underpins the core neuropsychological deficits. Blackwell Munksgaard, 2004

The Independence and Interdependence of Coacting Observers in Regard to Performance Efficiency, Workload, and Stress in a Vigilance Task.

PubMed

Funke, Gregory J; Warm, Joel S; Baldwin, Carryl L; Garcia, Andre; Funke, Matthew E; Dillard, Michael B; Finomore, Victor S; Matthews, Gerald; Greenlee, Eric T

2016-09-01

We investigated performance, workload, and stress in groups of paired observers who performed a vigilance task in a coactive (independent) manner. Previous studies have demonstrated that groups of coactive observers detect more signals in a vigilance task than observers working alone. Therefore, the use of such groups might be effective in enhancing signal detection in operational situations. However, concern over appearing less competent than one's cohort might induce elevated levels of workload and stress in coactive group members and thereby undermine group performance benefits. Accordingly, we performed the initial experiment comparing workload and stress in observers who performed a vigilance task coactively with those of observers who performed the vigilance task alone. Observers monitored a video display for collision flight paths in a simulated unmanned aerial vehicle control task. Self-reports of workload and stress were secured via the NASA-Task Load Index and the Dundee Stress State Questionnaire, respectively. Groups of coactive observers detected significantly more signals than did single observers. Coacting observers did not differ significantly from those operating by themselves in terms of workload but did in regard to stress; posttask distress was significantly lower for coacting than for single observers. Performing a visual vigilance task in a coactive manner with another observer does not elevate workload above that of observers working alone and serves to attenuate the stress associated with vigilance task performance. The use of coacting observers could be an effective vehicle for enhancing performance efficiency in operational vigilance. © 2016, Human Factors and Ergonomics Society.

Comparison of the Working Memory Load in N-Back and Working Memory Span Tasks by Means of EEG Frequency Band Power and P300 Amplitude

PubMed Central

Scharinger, Christian; Soutschek, Alexander; Schubert, Torsten; Gerjets, Peter

2017-01-01

According to theoretical accounts, both, N-back and complex span tasks mainly require working memory (WM) processing. In contrast, simple span tasks conceptually mainly require WM storage. Thus, conceptually, an N-back task and a complex span task share more commonalities as compared to a simple span task. In the current study, we compared an N-back task, a complex operation span task (Ospan), and a simple digit span task (Dspan) by means of typical WM load-related measures of the Electroencephalogram (EEG) like the parietal alpha and beta frequency band power, the frontal theta frequency band power, and the P300 amplitude, to examine whether these tasks would show commonalities or differences in WM processing-load. We expected that increasing WM-load would generally lead to a decreased alpha and beta frequency band power, an increased theta frequency band power, and a decreased P300 amplitude. Yet, based on the conceptual considerations, we hypothesized that the outcomes of these measures would be more comparable between the N-back and the Ospan as compared to the Dspan. Our hypotheses were partly confirmed. The N-back and the Ospan showed timely more prolonged alpha frequency band power effects as compared to the Dspan. This might indicate higher demands on WM processing in the former two tasks. The theta frequency band power and the P300 amplitude were most pronounced in the N-back task as compared to both span tasks. This might indicate specific demands on cognitive control in the N-back task. Additionally, we observed that behavioral performance measures correlated with changes in EEG alpha power of the N-back and the Ospan, yet not of the Dspan. Taken together, the hypothesized conceptual commonalities between the N-back task and the Ospan (and, for the Dspan, differences) were only partly confirmed by the electrophysiological WM load-related measures, indicating a potential need for reconsidering the theoretical accounts on WM tasks and the value of a closer link to electrophysiological research herein. PMID:28179880

Comparison of the Working Memory Load in N-Back and Working Memory Span Tasks by Means of EEG Frequency Band Power and P300 Amplitude.

PubMed

Scharinger, Christian; Soutschek, Alexander; Schubert, Torsten; Gerjets, Peter

2017-01-01

According to theoretical accounts, both, N -back and complex span tasks mainly require working memory (WM) processing. In contrast, simple span tasks conceptually mainly require WM storage. Thus, conceptually, an N -back task and a complex span task share more commonalities as compared to a simple span task. In the current study, we compared an N -back task, a complex operation span task (Ospan), and a simple digit span task (Dspan) by means of typical WM load-related measures of the Electroencephalogram (EEG) like the parietal alpha and beta frequency band power, the frontal theta frequency band power, and the P300 amplitude, to examine whether these tasks would show commonalities or differences in WM processing-load. We expected that increasing WM-load would generally lead to a decreased alpha and beta frequency band power, an increased theta frequency band power, and a decreased P300 amplitude. Yet, based on the conceptual considerations, we hypothesized that the outcomes of these measures would be more comparable between the N -back and the Ospan as compared to the Dspan. Our hypotheses were partly confirmed. The N -back and the Ospan showed timely more prolonged alpha frequency band power effects as compared to the Dspan. This might indicate higher demands on WM processing in the former two tasks. The theta frequency band power and the P300 amplitude were most pronounced in the N -back task as compared to both span tasks. This might indicate specific demands on cognitive control in the N -back task. Additionally, we observed that behavioral performance measures correlated with changes in EEG alpha power of the N -back and the Ospan, yet not of the Dspan. Taken together, the hypothesized conceptual commonalities between the N -back task and the Ospan (and, for the Dspan, differences) were only partly confirmed by the electrophysiological WM load-related measures, indicating a potential need for reconsidering the theoretical accounts on WM tasks and the value of a closer link to electrophysiological research herein.

Content Validity Index and Intra- and Inter-Rater Reliability of a New Muscle Strength/Endurance Test Battery for Swedish Soldiers

PubMed Central

Larsson, Helena; Tegern, Matthias; Monnier, Andreas; Skoglund, Jörgen; Helander, Charlotte; Persson, Emelie; Malm, Christer; Broman, Lisbet; Aasa, Ulrika

2015-01-01

The objective of this study was to examine the content validity of commonly used muscle performance tests in military personnel and to investigate the reliability of a proposed test battery. For the content validity investigation, thirty selected tests were those described in the literature and/or commonly used in the Nordic and North Atlantic Treaty Organization (NATO) countries. Nine selected experts rated, on a four-point Likert scale, the relevance of these tests in relation to five different work tasks: lifting, carrying equipment on the body or in the hands, climbing, and digging. Thereafter, a content validity index (CVI) was calculated for each work task. The result showed excellent CVI (≥0.78) for sixteen tests, which comprised of one or more of the military work tasks. Three of the tests; the functional lower-limb loading test (the Ranger test), dead-lift with kettlebells, and back extension, showed excellent content validity for four of the work tasks. For the development of a new muscle strength/endurance test battery, these three tests were further supplemented with two other tests, namely, the chins and side-bridge test. The inter-rater reliability was high (intraclass correlation coefficient, ICC2,1 0.99) for all five tests. The intra-rater reliability was good to high (ICC3,1 0.82–0.96) with an acceptable standard error of mean (SEM), except for the side-bridge test (SEM%>15). Thus, the final suggested test battery for a valid and reliable evaluation of soldiers’ muscle performance comprised the following four tests; the Ranger test, dead-lift with kettlebells, chins, and back extension test. The criterion-related validity of the test battery should be further evaluated for soldiers exposed to varying physical workload. PMID:26177030

Effects of working memory load on processing of sounds and meanings of words in aphasia

PubMed Central

Martin, Nadine; Kohen, Francine; Kalinyak-Fliszar, Michelene; Soveri, Anna; Laine, Matti

2011-01-01

Background Language performance in aphasia can vary depending on several variables such as stimulus characteristics and task demands. This study focuses on the degree of verbal working memory (WM) load inherent in the language task and how this variable affects language performance by individuals with aphasia. Aims The first aim was to identify the effects of increased verbal WM load on the performance of judgments of semantic similarity (synonymy) and phonological similarity (rhyming). The second aim was to determine if any of the following abilities could modulate the verbal WM load effect: semantic or phonological access, semantic or phonological short-term memory (STM) and any of the following executive processing abilities: inhibition, verbal WM updating, and set shifting. Method and Procedures Thirty-one individuals with aphasia and 11 controls participated in this study. They were administered a synonymy judgment task and a rhyming judgment task under high and low verbal WM load conditions that were compared to each other. In a second set of analyses, multiple regression was used to identify which factors (as noted above) modulated the verbal WM load effect. Outcome and Results For participants with aphasia, increased verbal WM load significantly reduced accuracy of performance on synonymy and rhyming judgments. Better performance in the low verbal WM load conditions was evident even after correcting for chance. The synonymy task included concrete and abstract word triplets. When these were examined separately, the verbal WM load effect was significant for the abstract words, but not the concrete words. The same pattern was observed in the performance of the control participants. Additionally, the second set of analyses revealed that semantic STM and one executive function, inhibition ability, emerged as the strongest predictors of the verbal WM load effect in these judgment tasks for individuals with aphasia. Conclusions The results of this study have important implications for diagnosis and treatment of aphasia. As the roles of verbal STM capacity, executive functions and verbal WM load in language processing are better understood, measurements of these variables can be incorporated into our diagnostic protocols. Moreover, if cognitive abilities such as STM and executive functions support language processing and their impairment adversely affects language function, treating them directly in the context of language tasks should translate into improved language function. PMID:22544993

A Framework for Load Balancing of Tensor Contraction Expressions via Dynamic Task Partitioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Pai-Wei; Stock, Kevin; Rajbhandari, Samyam

In this paper, we introduce the Dynamic Load-balanced Tensor Contractions (DLTC), a domain-specific library for efficient task parallel execution of tensor contraction expressions, a class of computation encountered in quantum chemistry and physics. Our framework decomposes each contraction into smaller unit of tasks, represented by an abstraction referred to as iterators. We exploit an extra level of parallelism by having tasks across independent contractions executed concurrently through a dynamic load balancing run- time. We demonstrate the improved performance, scalability, and flexibility for the computation of tensor contraction expressions on parallel computers using examples from coupled cluster methods.

Attentional load modulates responses of human primary visual cortex to invisible stimuli.

PubMed

Bahrami, Bahador; Lavie, Nilli; Rees, Geraint

2007-03-20

Visual neuroscience has long sought to determine the extent to which stimulus-evoked activity in visual cortex depends on attention and awareness. Some influential theories of consciousness maintain that the allocation of attention is restricted to conscious representations [1, 2]. However, in the load theory of attention [3], competition between task-relevant and task-irrelevant stimuli for limited-capacity attention does not depend on conscious perception of the irrelevant stimuli. The critical test is whether the level of attentional load in a relevant task would determine unconscious neural processing of invisible stimuli. Human participants were scanned with high-field fMRI while they performed a foveal task of low or high attentional load. Irrelevant, invisible monocular stimuli were simultaneously presented peripherally and were continuously suppressed by a flashing mask in the other eye [4]. Attentional load in the foveal task strongly modulated retinotopic activity evoked in primary visual cortex (V1) by the invisible stimuli. Contrary to traditional views [1, 2, 5, 6], we found that availability of attentional capacity determines neural representations related to unconscious processing of continuously suppressed stimuli in human primary visual cortex. Spillover of attention to cortical representations of invisible stimuli (under low load) cannot be a sufficient condition for their awareness.

Multitasking during social interactions in adolescence and early adulthood

PubMed Central

Mills, Kathryn L.; Dumontheil, Iroise; Speekenbrink, Maarten; Blakemore, Sarah-Jayne

2015-01-01

Multitasking is part of the everyday lives of both adolescents and adults. We often multitask during social interactions by simultaneously keeping track of other non-social information. Here, we examined how keeping track of non-social information impacts the ability to navigate social interactions in adolescents and adults. Participants aged 11–17 and 22–30 years old were instructed to carry out two tasks, one social and one non-social, within each trial. The social task involved referential communication, requiring participants to use social cues to guide their decisions, which sometimes required taking a different perspective. The non-social task manipulated cognitive load by requiring participants to remember non-social information in the form of one two-digit number (low load) or three two-digit numbers (high load) presented before each social task stimulus. Participants showed performance deficits when under high cognitive load and when the social task involved taking a different perspective, and individual differences in both trait perspective taking and working memory capacity predicted performance. Overall, adolescents were less adept at multitasking than adults when under high cognitive load. These results suggest that multitasking during social interactions incurs performance deficits, and that adolescents are more sensitive than adults to the effects of cognitive load while multitasking. PMID:26715991

Multitasking during social interactions in adolescence and early adulthood.

PubMed

Mills, Kathryn L; Dumontheil, Iroise; Speekenbrink, Maarten; Blakemore, Sarah-Jayne

2015-11-01

Multitasking is part of the everyday lives of both adolescents and adults. We often multitask during social interactions by simultaneously keeping track of other non-social information. Here, we examined how keeping track of non-social information impacts the ability to navigate social interactions in adolescents and adults. Participants aged 11-17 and 22-30 years old were instructed to carry out two tasks, one social and one non-social, within each trial. The social task involved referential communication, requiring participants to use social cues to guide their decisions, which sometimes required taking a different perspective. The non-social task manipulated cognitive load by requiring participants to remember non-social information in the form of one two-digit number (low load) or three two-digit numbers (high load) presented before each social task stimulus. Participants showed performance deficits when under high cognitive load and when the social task involved taking a different perspective, and individual differences in both trait perspective taking and working memory capacity predicted performance. Overall, adolescents were less adept at multitasking than adults when under high cognitive load. These results suggest that multitasking during social interactions incurs performance deficits, and that adolescents are more sensitive than adults to the effects of cognitive load while multitasking.

Superordinate Level Processing Has Priority Over Basic-Level Processing in Scene Gist Recognition

PubMed Central

Sun, Qi; Zheng, Yang; Sun, Mingxia; Zheng, Yuanjie

2016-01-01

By combining a perceptual discrimination task and a visuospatial working memory task, the present study examined the effects of visuospatial working memory load on the hierarchical processing of scene gist. In the perceptual discrimination task, two scene images from the same (manmade–manmade pairing or natural–natural pairing) or different superordinate level categories (manmade–natural pairing) were presented simultaneously, and participants were asked to judge whether these two images belonged to the same basic-level category (e.g., street–street pairing) or not (e.g., street–highway pairing). In the concurrent working memory task, spatial load (position-based load in Experiment 1) and object load (figure-based load in Experiment 2) were manipulated. The results were as follows: (a) spatial load and object load have stronger effects on discrimination of same basic-level scene pairing than same superordinate level scene pairing; (b) spatial load has a larger impact on the discrimination of scene pairings at early stages than at later stages; on the contrary, object information has a larger influence on at later stages than at early stages. It followed that superordinate level processing has priority over basic-level processing in scene gist recognition and spatial information contributes to the earlier and object information to the later stages in scene gist recognition. PMID:28382195

The roles of sensory function and cognitive load in age differences in inhibition: Evidence from the Stroop task.

PubMed

Peng, Huamao; Gao, Yue; Mao, Xiaofei

2017-02-01

To explore the roles of visual function and cognitive load in aging of inhibition, the present study adopted a 2 (visual perceptual stress: noise, nonnoise) × 2 (cognitive load: low, high) × 2 (age: young, old) mixed design. The Stroop task was adopted to measure inhibition. The task presentation was masked with Gaussian noise according to the visual function of each individual in order to match visual perceptual stress between age groups. The results indicated that age differences in the Stroop effect were influenced by visual function and cognitive load. When the cognitive load was low, older adults exhibited a larger Stroop effect than did younger adults in the nonnoise condition, and this age difference disappeared when the visual noise of the 2 age groups was matched. Conversely, in the high cognitive load condition, we observed significant age differences in the Stroop effect in both the nonnoise and noise conditions. The additional cognitive load made the age differences in the Stroop task reappear even when visual perceptual stress was equivalent. These results demonstrate that visual function plays an important role in the aging of inhibition and its role is moderated by cognitive load. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Spatial release of cognitive load measured in a dual-task paradigm in normal-hearing and hearing-impaired listeners.

PubMed

Xia, Jing; Nooraei, Nazanin; Kalluri, Sridhar; Edwards, Brent

2015-04-01

This study investigated whether spatial separation between talkers helps reduce cognitive processing load, and how hearing impairment interacts with the cognitive load of individuals listening in multi-talker environments. A dual-task paradigm was used in which performance on a secondary task (visual tracking) served as a measure of the cognitive load imposed by a speech recognition task. Visual tracking performance was measured under four conditions in which the target and the interferers were distinguished by (1) gender and spatial location, (2) gender only, (3) spatial location only, and (4) neither gender nor spatial location. Results showed that when gender cues were available, a 15° spatial separation between talkers reduced the cognitive load of listening even though it did not provide further improvement in speech recognition (Experiment I). Compared to normal-hearing listeners, large individual variability in spatial release of cognitive load was observed among hearing-impaired listeners. Cognitive load was lower when talkers were spatially separated by 60° than when talkers were of different genders, even though speech recognition was comparable in these two conditions (Experiment II). These results suggest that a measure of cognitive load might provide valuable insight into the benefit of spatial cues in multi-talker environments.

An analysis of the suitability of a low-cost eye tracker for assessing the cognitive load of drivers.

PubMed

Čegovnik, Tomaž; Stojmenova, Kristina; Jakus, Grega; Sodnik, Jaka

2018-04-01

This paper presents a driving simulator study in which we investigated whether the Eye Tribe eye tracker (ET) is capable of assessing changes in the cognitive load of drivers through oculography and pupillometry. In the study, participants were asked to drive a simulated vehicle and simultaneously perform a set of secondary tasks with different cognitive complexity levels. We measured changes in eye properties, such as the pupil size, blink rate and fixation time. We also performed a measurement with a Detection Response Task (DRT) to validate the results and to prove a steady increase of cognitive load with increasing secondary task difficulty. The results showed that the ET precisely recognizes an increasing pupil diameter with increasing secondary task difficulty. In addition, the ET shows increasing blink rates, decreasing fixation time and narrowing of the attention field with increasing secondary task difficulty. The results were validated with the DRT method and the secondary task performance. We conclude that the Eye Tribe ET is a suitable device for assessing a driver's cognitive load. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cost Efficiency of Sea Freight and Lowering Cost of Consumption Goods

NASA Astrophysics Data System (ADS)

Rum, Muh

2018-05-01

The subject of this research are administrative processes related to loading and unloading costin term of a ship’s arrival and departure to seaports,typically attributed to elevated levels of cost of labor, handling cost, dwelling time, and port fee which required to complete the related administrative tasks. Research design by comparative method in administrative way, which compare with many way implemented of previous practitioner export and import. In the previous phases of the research, an average expected cost of the administrative labor cost in traditional seaport clusters in eastern Indonesia was identified and quantified on an hourly basis. This research continues in its aim by using the results of the previous research as a starting point, and Find that enterprise resource planning and improvement, transactional due diligence and merger integration, positively affect and not associated with cost reduction. Moreover variable of reducing inventory cost affect and associated with reducing cost. The main hypothesis is that the usage of such a new model will result in a measurable decrease of the required freight cost in sea port, which indirectly reduce the consumption goods.

The Composite Strain Index (COSI) and Cumulative Strain Index (CUSI): methodologies for quantifying biomechanical stressors for complex tasks and job rotation using the Revised Strain Index.

PubMed

Garg, Arun; Moore, J Steven; Kapellusch, Jay M

2017-08-01

The Composite Strain Index (COSI) quantifies biomechanical stressors for complex tasks consisting of exertions at different force levels and/or with different exertion times. The Cumulative Strain Index (CUSI) further integrates biomechanical stressors from different tasks to quantify exposure for the entire work shift. The paper provides methodologies to compute COSI and CUSI along with examples. Complex task simulation produced 169,214 distinct tasks. Use of average, time-weighted average (TWA) and peak force and COSI classified 66.9, 28.2, 100 and 38.9% of tasks as hazardous, respectively. For job rotation the simulation produced 10,920 distinct jobs. TWA COSI, peak task COSI and CUSI classified 36.5, 78.1 and 66.6% jobs as hazardous, respectively. The results suggest that the TWA approach systematically underestimates the biomechanical stressors and peak approach overestimates biomechanical stressors, both at the task and job level. It is believed that the COSI and CUSI partially address these underestimations and overestimations of biomechanical stressors. Practitioner Summary: COSI quantifies exposure when applied hand force and/or duration of that force changes during a task cycle. CUSI integrates physical exposures from job rotation. These should be valuable tools for designing and analysing tasks and job rotation to determine risk of musculoskeletal injuries.

Modulating Arm Swing Symmetry with Cognitive Load: A Window on Rhythmic Spinal Locomotor Networks in Humans?

PubMed

Killeen, Tim; Easthope, Christopher S; Filli, Linard; Linnebank, Michael; Curt, Armin; Bolliger, Marc; Zörner, Björn

2017-05-15

In healthy subjects, changes in arm swing symmetry while walking are observed when a cognitive dual task is added, with a tendency toward left-dominant arm swing as cognitive load increases. We applied a modified Stroop word/color naming paradigm to investigate this effect in spinal cord injured (SCI) patients. Six patients with cervical SCI (cSCI), 6 with thoracic injuries (tSCI; all 12 patients American Spinal Injury Association [ASIA] Injury Score [AIS]D), and 12 healthy, matched controls underwent three-dimensional 3D gait analysis while walking normally at a comfortable speed (NW) and when performing an additional congruent (CS) and incongruent (IS) Stroop task. An arm swing symmetry index (ASI)-in which positive values indicate proportionally more movement on the left and vice versa-was calculated. Even in the baseline NW condition, all three subject groups showed larger arm movements on the left. In controls, ASI increased (NW, 13.7 ± 6.3; CS, 16.6 ± 6.4; IS, 19.6 ± 7.8) as the task became more demanding. A larger shift in tSCI patients (NW, 15.8 ± 6.0; CS, 23.4 ± 3.8; IS, 30.7 ± 4.4) was driven by a significant reduction in right wrist trajectory (p = 0.014), whereas cSCI patients showed a small reduction in mean ASI with high variability (NW, 14.2 ± 10.7; CS, 9.3 ± 13.5; IS, 6.0 ± 12.9). The effect of the IS task on ASI compared to baseline (NW) was significantly different between tSCI (+12.5 ± 6.3) and cSCI (-8.2 ± 6.0) patients (p = 0.011). Disruption of the long propriospinal connections coordinating arm and leg movements during walking may explain the heightened sensitivity to manipulation of cognitive load in tSCI, whereas the more robust automaticity in cSCI may be attributed to impaired supraspinal inputs in the context of preserved intraspinal pathways.

Dissociable Roles of Different Types of Working Memory Load in Visual Detection

PubMed Central

Konstantinou, Nikos; Lavie, Nilli

2013-01-01

We contrasted the effects of different types of working memory (WM) load on detection. Considering the sensory-recruitment hypothesis of visual short-term memory (VSTM) within load theory (e.g., Lavie, 2010) led us to predict that VSTM load would reduce visual-representation capacity, thus leading to reduced detection sensitivity during maintenance, whereas load on WM cognitive control processes would reduce priority-based control, thus leading to enhanced detection sensitivity for a low-priority stimulus. During the retention interval of a WM task, participants performed a visual-search task while also asked to detect a masked stimulus in the periphery. Loading WM cognitive control processes (with the demand to maintain a random digit order [vs. fixed in conditions of low load]) led to enhanced detection sensitivity. In contrast, loading VSTM (with the demand to maintain the color and positions of six squares [vs. one in conditions of low load]) reduced detection sensitivity, an effect comparable with that found for manipulating perceptual load in the search task. The results confirmed our predictions and established a new functional dissociation between the roles of different types of WM load in the fundamental visual perception process of detection. PMID:23713796

Gender differences in plantar loading during three soccer-specific tasks.

PubMed

Sims, E L; Hardaker, W M; Queen, R M

2008-04-01

Examine the effect of gender on plantar loading during three football-specific tasks. Thirty-four athletes (17 men, 17 women) ran an agility course five times while wearing the Nike Vitoria hard ground cleat. Plantar loading data were recorded during a side cut, a cross-over cut and a forward acceleration task using Pedar-X insoles. Controlled laboratory study. No history of lower extremity injury in the past 6 months, no previous foot or ankle surgery, not currently wearing foot orthotics and play a cleated sport at least two times per week. Contact area, maximum force and the force-time integral (FTI) in the medial and lateral midfoot, medial, middle and lateral forefoot as well as the hallux. A univariate ANCOVA (alpha = 0.05) was performed on each dependent variable (covariate was course speed). Significant gender differences existed in the force and force-time integral beneath the lateral midfoot and forefoot during the cross-over cut task as well as in the middle forefoot during the side cut task with the men demonstrating an increased force. No significant differences existed in the loading on the medial side of the foot during any tasks. The results of this study indicate that the increase in plantar loading on the lateral portion of the midfoot and forefoot in men could be one possible explanation for the increased incidence of fifth metatarsal stress fractures in men. Gender differences in loading patterns need to be considered when comparing different movements as well as different footwear conditions.

Attention and Working Memory in Adolescents with Autism Spectrum Disorder: A Functional MRI Study.

PubMed

Rahko, Jukka S; Vuontela, Virve A; Carlson, Synnöve; Nikkinen, Juha; Hurtig, Tuula M; Kuusikko-Gauffin, Sanna; Mattila, Marja-Leena; Jussila, Katja K; Remes, Jukka J; Jansson-Verkasalo, Eira M; Aronen, Eeva T; Pauls, David L; Ebeling, Hanna E; Tervonen, Osmo; Moilanen, Irma K; Kiviniemi, Vesa J

2016-06-01

The present study examined attention and memory load-dependent differences in the brain activation and deactivation patterns between adolescents with autism spectrum disorders (ASDs) and typically developing (TD) controls using functional magnetic resonance imaging. Attentional (0-back) and working memory (WM; 2-back) processing and load differences (0 vs. 2-back) were analysed. WM-related areas activated and default mode network deactivated normally in ASDs as a function of task load. ASDs performed the attentional 0-back task similarly to TD controls but showed increased deactivation in cerebellum and right temporal cortical areas and weaker activation in other cerebellar areas. Increasing task load resulted in multiple responses in ASDs compared to TD and in inadequate modulation of brain activity in right insula, primary somatosensory, motor and auditory cortices. The changes during attentional task may reflect compensatory mechanisms enabling normal behavioral performance. The inadequate memory load-dependent modulation of activity suggests diminished compensatory potential in ASD.

Pupillary response to complex interdependent tasks: A cognitive-load theory perspective.

PubMed

Mitra, Ritayan; McNeal, Karen S; Bondell, Howard D

2017-10-01

Pupil dilation is known to indicate cognitive load. In this study, we looked at the average pupillary responses of a cohort of 29 undergraduate students during graphical problem solving. Three questions were asked, based on the same graphical input. The questions were interdependent and comprised multiple steps. We propose a novel way of analyzing pupillometry data for such tasks on the basis of eye fixations, a commonly used eyetracking parameter. We found that pupil diameter increased during the solution process. However, pupil diameter did not always reflect the expected cognitive load. This result was studied within a cognitive-load theory model. Higher-performing students showed evidence of germane load and schema creation, indicating use of the interdependent nature of the tasks to inform their problem-solving process. However, lower-performing students did not recognize the interdependent nature of the tasks and solved each problem independently, which was expressed in a markedly different pupillary response pattern. We discuss the import of our findings for instructional design.

Is masked priming modulated by memory load? A test of the automaticity of masked identity priming in lexical decision.

PubMed

Perea, Manuel; Marcet, Ana; Lozano, Mario; Gomez, Pablo

2018-05-29

One of the key assumptions of the masked priming lexical decision task (LDT) is that primes are processed without requiring attentional resources. Here, we tested this assumption by presenting a dual-task manipulation to increase memory load and measure the change in masked identity priming on the targets in the LDT. If masked priming does not require attentional resources, increased memory load should have no influence on the magnitude of the observed identity priming effects. We conducted two LDT experiments, using a within-subjects design, to investigate the effect of memory load (via a concurrent matching task Experiment 1 and a concurrent search task in Experiment 2) on masked identity priming. Results showed that the magnitude of masked identity priming on word targets was remarkably similar under high and low memory load. Thus, these experiments provide empirical evidence for the automaticity assumption of masked identity priming in the LDT.

28 CFR 542.19 - Access to indexes and responses.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Access to indexes and responses. 542.19... ADMINISTRATIVE REMEDY Administrative Remedy Program § 542.19 Access to indexes and responses. Inmates and members of the public may request access to Administrative Remedy indexes and responses, for which inmate...

Cognitive load effects on early visual perceptual processing.

PubMed

Liu, Ping; Forte, Jason; Sewell, David; Carter, Olivia

2018-05-01

Contrast-based early visual processing has largely been considered to involve autonomous processes that do not need the support of cognitive resources. However, as spatial attention is known to modulate early visual perceptual processing, we explored whether cognitive load could similarly impact contrast-based perception. We used a dual-task paradigm to assess the impact of a concurrent working memory task on the performance of three different early visual tasks. The results from Experiment 1 suggest that cognitive load can modulate early visual processing. No effects of cognitive load were seen in Experiments 2 or 3. Together, the findings provide evidence that under some circumstances cognitive load effects can penetrate the early stages of visual processing and that higher cognitive function and early perceptual processing may not be as independent as was once thought.

Asymmetric Spatial Processing Under Cognitive Load.

PubMed

Naert, Lien; Bonato, Mario; Fias, Wim

2018-01-01

Spatial attention allows us to selectively process information within a certain location in space. Despite the vast literature on spatial attention, the effect of cognitive load on spatial processing is still not fully understood. In this study we added cognitive load to a spatial processing task, so as to see whether it would differentially impact upon the processing of visual information in the left versus the right hemispace. The main paradigm consisted of a detection task that was performed during the maintenance interval of a verbal working memory task. We found that increasing cognitive working memory load had a more negative impact on detecting targets presented on the left side compared to those on the right side. The strength of the load effect correlated with the strength of the interaction on an individual level. The implications of an asymmetric attentional bias with a relative disadvantage for the left (vs the right) hemispace under high verbal working memory (WM) load are discussed.

Observing prioritization effects on cognition and gait: The effect of increased cognitive load on cognitively healthy older adults' dual-task performance.

PubMed

Maclean, Linda M; Brown, Laura J E; Khadra, H; Astell, Arlene J

2017-03-01

Previous studies exploring the effects of attention-prioritization on cognitively healthy older adults' gait and cognitive dual task (DT) performance have shown DT cost in gait outcomes but inconsistent effects on cognitive performance, which may reflect task difficulty (the cognitive load). This study aimed to identify whether changing the cognitive load during a walking and counting DT improved the challenge/sensitivity of the cognitive task to observe prioritization effects on concurrent gait and cognitive performance outcomes. Seventy-two cognitively healthy older adults (Mean=73years) walked 15m, counted backwards in 3s and 7s as single tasks (ST), and concurrently walked and counted backwards as DTs. Attention-prioritization was examined in Prioritizing Walking (PW) and Prioritizing Counting (PC) DT conditions. Dual-task performance costs (DTC) were calculated for number of correct cognitive responses (CCR) in the counting tasks, and step-time variability and velocity in the gait task. All DT conditions showed a benefit (DTB) for cognitive outcomes with trade-off cost to gait. In the Serial 3s task, the cognitive DTBs increased in PC over the PW condition (p<0.05), with a greater cost to walking velocity (p<0.05). DT effects were more pronounced in the Serial 7s with a lower cognitive DTB when PC than when PW, (p<0.05) with no trade-off increase in cost to gait outcomes (p<0.05). The findings suggest that increased cognitive load during a gait and cognitive DT produces more pronounced gait measures of attention-prioritization in cognitively healthy older adults. A cognitive load effect was also observed in the cognitive outcomes, with unexpected results. Copyright © 2017 Elsevier B.V. All rights reserved.

Visual Task Demands and the Auditory Mismatch Negativity: An Empirical Study and a Meta-Analysis

PubMed Central

Wiens, Stefan; Szychowska, Malina; Nilsson, Mats E.

2016-01-01

Because the auditory system is particularly useful in monitoring the environment, previous research has examined whether task-irrelevant, auditory distracters are processed even if subjects focus their attention on visual stimuli. This research suggests that attentionally demanding visual tasks decrease the auditory mismatch negativity (MMN) to simultaneously presented auditory distractors. Because a recent behavioral study found that high visual perceptual load decreased detection sensitivity of simultaneous tones, we used a similar task (n = 28) to determine if high visual perceptual load would reduce the auditory MMN. Results suggested that perceptual load did not decrease the MMN. At face value, these nonsignificant findings may suggest that effects of perceptual load on the MMN are smaller than those of other demanding visual tasks. If so, effect sizes should differ systematically between the present and previous studies. We conducted a selective meta-analysis of published studies in which the MMN was derived from the EEG, the visual task demands were continuous and varied between high and low within the same task, and the task-irrelevant tones were presented in a typical oddball paradigm simultaneously with the visual stimuli. Because the meta-analysis suggested that the present (null) findings did not differ systematically from previous findings, the available evidence was combined. Results of this meta-analysis confirmed that demanding visual tasks reduce the MMN to auditory distracters. However, because the meta-analysis was based on small studies and because of the risk for publication biases, future studies should be preregistered with large samples (n > 150) to provide confirmatory evidence for the results of the present meta-analysis. These future studies should also use control conditions that reduce confounding effects of neural adaptation, and use load manipulations that are defined independently from their effects on the MMN. PMID:26741815

Robust Multimodal Cognitive Load Measurement

DTIC Science & Technology

2014-03-26

dimension, Hurst exponent ) of electroencephalogram (EEG) signals to evaluate changes in working memory load during the performance of a cognitive task...dimension, Hurst exponent ) of electroencephalogram (EEG) signals to evaluate changes in working memory load during the performance of a cognitive task with...approximate entropies, wavelet-based complexity measures, correlation dimension, Hurst exponent ) of electroencephalogram (EEG) signals to evaluate changes

Indexing Learning Objects: Vocabularies and Empirical Investigation of Consistency

ERIC Educational Resources Information Center

Kabel, Suzanne; De Hoog, Robert; Wielinga, Bob; Anjewierden, Anjo

2004-01-01

In addition to the LOM standard and instructional design specifications, as well as domain specific indexing vocabularies, a structured indexing vocabulary for the more elementary learning objects is advisable in order to support retrieval tasks of developers. Furthermore, because semantic indexing is seen as a difficult task, three issues…

Divergent Effects of Cognitive Load on Quiet Stance and Task-Linked Postural Coordination

ERIC Educational Resources Information Center

Mitra, Suvobrata; Knight, Alec; Munn, Alexandra

2013-01-01

Performing a cognitive task while maintaining upright stance can lead to increased or reduced body sway depending on tasks and experimental conditions. Because greater sway is commonly taken to indicate loosened postural control, and vice versa, the precise impact of cognitive load on postural stability has remained unclear. In much of the large…

Toward a better understanding of task demands, workload, and performance during physician-computer interactions.

PubMed

Mazur, Lukasz M; Mosaly, Prithima R; Moore, Carlton; Comitz, Elizabeth; Yu, Fei; Falchook, Aaron D; Eblan, Michael J; Hoyle, Lesley M; Tracton, Gregg; Chera, Bhishamjit S; Marks, Lawrence B

2016-11-01

To assess the relationship between (1) task demands and workload, (2) task demands and performance, and (3) workload and performance, all during physician-computer interactions in a simulated environment. Two experiments were performed in 2 different electronic medical record (EMR) environments: WebCIS (n = 12) and Epic (n = 17). Each participant was instructed to complete a set of prespecified tasks on 3 routine clinical EMR-based scenarios: urinary tract infection (UTI), pneumonia (PN), and heart failure (HF). Task demands were quantified using behavioral responses (click and time analysis). At the end of each scenario, subjective workload was measured using the NASA-Task-Load Index (NASA-TLX). Physiological workload was measured using pupillary dilation and electroencephalography (EEG) data collected throughout the scenarios. Performance was quantified based on the maximum severity of omission errors. Data analysis indicated that the PN and HF scenarios were significantly more demanding than the UTI scenario for participants using WebCIS (P < .01), and that the PN scenario was significantly more demanding than the UTI and HF scenarios for participants using Epic (P < .01). In both experiments, the regression analysis indicated a significant relationship only between task demands and performance (P < .01). Results suggest that task demands as experienced by participants are related to participants' performance. Future work may support the notion that task demands could be used as a quality metric that is likely representative of performance, and perhaps patient outcomes. The present study is a reasonable next step in a systematic assessment of how task demands and workload are related to performance in EMR-evolving environments. © The Author 2016. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The Chronic Detrimental Impact of Interruptions in a Simulated Submarine Track Management Task.

PubMed

Loft, Shayne; Sadler, Andreas; Braithwaite, Janelle; Huf, Samuel

2015-12-01

The objective of this article is to examine the extent to which interruptions negatively impact situation awareness and long-term performance in a submarine track management task where pre- and postinterruption display scenes remained essentially identical. Interruptions in command and control task environments can degrade performance well beyond the first postinterruption action typically measured for sequential static tasks, because individuals need to recover their situation awareness for multiple unfolding display events. Participants in the current study returned to an unchanged display scene following interruption and therefore could be more immune to such long-term performance deficits. The task required participants to monitor a display to detect contact heading changes and to make enemy engagement decisions. Situation awareness (Situation Present Assessment Method) and subjective workload (NASA-Task Load Index) were measured. The interruption replaced the display for 20 s with a blank screen, during which participants completed a classification task. Situation awareness after returning from interruption was degraded. Participants were slower to make correct engagement decisions and slower and less accurate in detecting heading changes, despite these task decisions being made at least 40 s following the interruption. Interruptions negatively impacted situation awareness and long-term performance because participants needed to redetermine the location and spatial relationship between the displayed contacts when returning from interruption, either because their situation awareness for the preinterruption scene decayed or because they did not encode the preinterruption scene. Interruption in work contexts such as submarines is unavoidable, and further understanding of how operators are affected is required to improve work design and training. © 2015, Human Factors and Ergonomics Society.

High Working Memory Load Impairs Language Processing during a Simulated Piloting Task: An ERP and Pupillometry Study

PubMed Central

Causse, Mickaël; Peysakhovich, Vsevolod; Fabre, Eve F.

2016-01-01

Given the important amount of visual and auditory linguistic information that pilots have to process, operating an aircraft generates a high working-memory load (WML). In this context, the ability to focus attention on relevant information and to remain responsive to concurrent stimuli might be altered. Consequently, understanding the effects of WML on the processing of both linguistic targets and distractors is of particular interest in the study of pilot performance. In the present work, participants performed a simplified piloting task in which they had to follow one of three colored aircraft, according to specific written instructions (i.e., the written word for the color corresponding to the color of one of the aircraft) and to ignore either congruent or incongruent concurrent auditory distractors (i.e., a spoken name of color). The WML was manipulated with an n-back sub-task. Participants were instructed to apply the current written instruction in the low WML condition, and the 2-back written instruction in the high WML condition. Electrophysiological results revealed a major effect of WML at behavioral (i.e., decline of piloting performance), electrophysiological, and autonomic levels (i.e., greater pupil diameter). Increased WML consumed resources that could not be allocated to the processing of the linguistic stimuli, as indexed by lower P300/P600 amplitudes. Also, significantly, lower P600 responses were measured in incongruent vs. congruent trials in the low WML condition, showing a higher difficulty reorienting attention toward the written instruction, but this effect was canceled in the high WML condition. This suppression of interference in the high load condition is in line with the engagement/distraction trade-off model. We propose that P300/P600 components could be reliable indicators of WML and that they allow an estimation of its impact on the processing of linguistic stimuli. PMID:27252639

High Working Memory Load Impairs Language Processing during a Simulated Piloting Task: An ERP and Pupillometry Study.

PubMed

Causse, Mickaël; Peysakhovich, Vsevolod; Fabre, Eve F

2016-01-01

Given the important amount of visual and auditory linguistic information that pilots have to process, operating an aircraft generates a high working-memory load (WML). In this context, the ability to focus attention on relevant information and to remain responsive to concurrent stimuli might be altered. Consequently, understanding the effects of WML on the processing of both linguistic targets and distractors is of particular interest in the study of pilot performance. In the present work, participants performed a simplified piloting task in which they had to follow one of three colored aircraft, according to specific written instructions (i.e., the written word for the color corresponding to the color of one of the aircraft) and to ignore either congruent or incongruent concurrent auditory distractors (i.e., a spoken name of color). The WML was manipulated with an n-back sub-task. Participants were instructed to apply the current written instruction in the low WML condition, and the 2-back written instruction in the high WML condition. Electrophysiological results revealed a major effect of WML at behavioral (i.e., decline of piloting performance), electrophysiological, and autonomic levels (i.e., greater pupil diameter). Increased WML consumed resources that could not be allocated to the processing of the linguistic stimuli, as indexed by lower P300/P600 amplitudes. Also, significantly, lower P600 responses were measured in incongruent vs. congruent trials in the low WML condition, showing a higher difficulty reorienting attention toward the written instruction, but this effect was canceled in the high WML condition. This suppression of interference in the high load condition is in line with the engagement/distraction trade-off model. We propose that P300/P600 components could be reliable indicators of WML and that they allow an estimation of its impact on the processing of linguistic stimuli.

Measuring achievement goal motivation, mindsets and cognitive load: validation of three instruments' scores.

PubMed

Cook, David A; Castillo, Richmond M; Gas, Becca; Artino, Anthony R

2017-10-01

Measurement of motivation and cognitive load has potential value in health professions education. Our objective was to evaluate the validity of scores from Dweck's Implicit Theories of Intelligence Scale (ITIS), Elliot's Achievement Goal Questionnaire-Revised (AGQ-R) and Leppink's cognitive load index (CLI). This was a validity study evaluating internal structure using reliability and factor analysis, and relationships with other variables using the multitrait-multimethod matrix. Two hundred and thirty-two secondary school students participated in a medical simulation-based training activity at an academic medical center. Pre-activity ITIS (implicit theory [mindset] domains: incremental, entity) and AGQ-R (achievement goal domains: mastery-approach, mastery-avoidance, performance-approach, performance-avoidance), post-activity CLI (cognitive load domains: intrinsic, extrinsic, germane) and task persistence (self-directed repetitions on a laparoscopic surgery task) were measured. Internal consistency reliability (Cronbach's alpha) was > 0.70 for all domain scores except AGQ-R performance-avoidance (alpha 0.68) and CLI extrinsic load (alpha 0.64). Confirmatory factor analysis of ITIS and CLI scores demonstrated acceptable model fit. Confirmatory factor analysis of AGQ-R scores demonstrated borderline fit, and exploratory factor analysis suggested a three-domain model for achievement goals (mastery-approach, performance and avoidance). Correlations among scores from conceptually-related domains generally aligned with expectations, as follows: ITIS incremental and entity, r = -0.52; AGQ-R mastery-avoidance and performance-avoidance, r = 0.71; mastery-approach and performance-approach, r = 0.55; performance-approach and performance-avoidance, r = 0.43; mastery-approach and mastery-avoidance, r = 0.36; CLI germane and extrinsic, r = -0.35; ITIS incremental and AGQ-R mastery-approach, r = 0.34; ITIS incremental and CLI germane, r = 0.44; AGQ-R mastery-approach and CLI germane, r = 0.48 (all p < 0.001). We found no correlation between the number of task repetitions (i.e. persistence) and mastery-approach scores, r = -0.01. ITIS and CLI scores had appropriate internal structures and relationships with other variables. AGQ-R scores fit a three-factor (not four-factor) model that collapsed avoidance into one domain, although relationships of other variables with the original four domain scores generally aligned with expectations. Mastery goals are positively correlated with germane cognitive load. © 2017 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

Stroop-like effects in a new-code learning task: A cognitive load theory perspective.

PubMed

Hazan-Liran, Batel; Miller, Paul

2017-09-01

To determine whether and how learning is biased by competing task-irrelevant information that creates extraneous cognitive load, we assessed the efficiency of university students with a learning paradigm in two experiments. The paradigm asked participants to learn associations between eight words and eight digits. We manipulated congruity of the digits' ink colour with the words' semantics. In Experiment 1 word stimuli were colour words (e.g., blue, yellow) and in Experiment 2 colour-related word concepts (e.g., sky, banana). Marked benefits and costs on learning due to variation in extraneous cognitive load originating from processing task-irrelevant information were evident. Implications for cognitive load theory and schooling are discussed.

Selling Health to the Distracted: Consumer Responses to Source Credibility and Ad Appeal Type in a Direct-to-Consumer Advertisement.

PubMed

Lemanski, Jennifer L; Villegas, Jorge

2015-01-01

Since 1997, when the U.S. Food and Drug Administration first allowed prescription drug companies to release ads directly targeting the public, direct-to-consumer (DTC) advertising has become an integral part of the pharmaceutical industry marketing toolkit, reaching over $4 billion in 2005. In an experiment where cognitive load, a task that requires the investment of a subject's memory in an unrelated task; source credibility; and advertising appeal type (affective or cognitive) were manipulated, attitude toward the ad was measured for a print DTC meningitis vaccine ad. Main effect results for source credibility and advertising appeal type on attitude toward the ad were found, and interactions between manipulated variables were apparent when the individual difference variables related to a specific illness (vaccination history, living in a dorm, family members or friends who had suffered the illness) were taken into account.

Cloud computing task scheduling strategy based on differential evolution and ant colony optimization

NASA Astrophysics Data System (ADS)

Ge, Junwei; Cai, Yu; Fang, Yiqiu

2018-05-01

This paper proposes a task scheduling strategy DEACO based on the combination of Differential Evolution (DE) and Ant Colony Optimization (ACO), aiming at the single problem of optimization objective in cloud computing task scheduling, this paper combines the shortest task completion time, cost and load balancing. DEACO uses the solution of the DE to initialize the initial pheromone of ACO, reduces the time of collecting the pheromone in ACO in the early, and improves the pheromone updating rule through the load factor. The proposed algorithm is simulated on cloudsim, and compared with the min-min and ACO. The experimental results show that DEACO is more superior in terms of time, cost, and load.

Professional or administrative value patterns? Clinical pathways in medical problem-solving processes.

PubMed

Holmberg, Leif

2007-11-01

A health-care organization simultaneously belongs to two different institutional value patterns: a professional and an administrative value pattern. At the administrative level, medical problem-solving processes are generally perceived as the efficient application of familiar chains of activities to well-defined problems; and a low task uncertainty is therefore assumed at the work-floor level. This assumption is further reinforced through clinical pathways and other administrative guidelines. However, studies have shown that in clinical practice such administrative guidelines are often considered inadequate and difficult to implement mainly because physicians generally perceive task uncertainty to be high and that the guidelines do not cover the scope of encountered deviations. The current administrative level guidelines impose uniform structural features that meet the requirement for low task uncertainty. Within these structural constraints, physicians must organize medical problem-solving processes to meet any task uncertainty that may be encountered. Medical problem-solving processes with low task uncertainty need to be organized independently of processes with high task uncertainty. Each process must be evaluated according to different performance standards and needs to have autonomous administrative guideline models. Although clinical pathways seem appropriate when there is low task uncertainty, other kinds of guidelines are required when the task uncertainty is high.

Changes in biomechanics and muscle activation in injured ballet dancers during a jump-land task with turnout (Sissonne Fermée).

PubMed

Lee, Hsing-Hsan; Lin, Chia-Wei; Wu, Hong-Wen; Wu, Tzu-Chuan; Lin, Cheng-Feng

2012-01-01

Large impact loading with abnormal muscle activity and motion patterns may contribute to lower extremity injuries in ballet dancers. Yet, few studies investigated the influence of injury on the ballet movement. The purpose of this study was to find the neuromuscular and biomechanical characteristics in dancers with and without ankle injury during a jump-landing Sissonne Fermée task. Twenty-two ballet dancers were recruited and divided into the injured group (n = 11) and the uninjured group (n = 11). They performed a ballet movement called "Sissonne Fermée" with reflective markers and electrodes attached to their lower extremities. Ground reaction force, joint kinematics, and muscle activity were measured. The injured dancers had greater peak ankle eversion but smaller hindfoot-to-tibial eversion angles. Also, the injured dancers had greater activity of the hamstring of the dominant leg and tibialis anterior of the non-dominant leg during the pre-landing phase. The injured dancers had greater tibialis anterior activity of the dominant leg but less muscle activity in the medial gastrocnemius of the non-dominant leg during the post-landing phase. The injured dancers had a greater co-contraction index in the non-dominant ankle and a lower loading rate. The higher co-contraction indices showed that the injured dancers required more muscle effort to control ankle stability. Furthermore, the injured dancers used a "load avoidance strategy" to protect themselves from re-injury. Neuromuscular control training of the ankle joint for ballet dancers to prevent injury is necessary.

Neural correlates of dual-task effect on belief-bias syllogistic reasoning: a near-infrared spectroscopy study.

PubMed

Tsujii, Takeo; Watanabe, Shigeru

2009-09-01

Recent dual-process reasoning theories have explained the belief-bias effect, the tendency for human reasoning to be erroneously biased when logical conclusions are incongruent with beliefs about the world, by proposing a belief-based automatic heuristic system and logic-based demanding analytic system. Although these claims are supported by the behavioral finding that high-load secondary tasks enhance the belief-bias effect, the neural correlates of dual-task reasoning remain unknown. The present study therefore examined the relationship between dual-task effect and activity in the inferior frontal cortex (IFC) during belief-bias reasoning by near-infrared spectroscopy (NIRS). Forty-eight subjects participated in this study (MA=23.46 years). They were required to perform congruent and incongruent reasoning trials while responding to high- and low-load secondary tasks. Behavioral analysis showed that the high-load secondary task impaired only incongruent reasoning performance. NIRS analysis found that the high-load secondary task decreased right IFC activity during incongruent trials. Correlation analysis showed that subjects with enhanced right IFC activity could perform better in the incongruent reasoning trials, though subjects for whom right IFC activity was impaired by the secondary task could not maintain better reasoning performance. These findings suggest that the right IFC may be responsible for the dual-task effect in conflicting reasoning processes. When secondary tasks impair right IFC activity, subjects may rely on the automatic heuristic system, which results in belief-bias responses. We therefore offer the first demonstration of neural correlates of dual-task effect on IFC activity in belief-bias reasoning.

Task Descriptions in Diagnostic Radiology. Research Report No. 7. Volume 4, Index of Tasks by Code Number and Extended Name.

ERIC Educational Resources Information Center

Gilpatrick, Eleanor

The fourth of four volumes in Research Report No. 7 of the Health Services Mobility Study (HSMS), this book contains the extended task names of all the tasks whose descriptions can be found in the three prior volumes. It serves as an index to all the tasks by listing the volume in which each task description appears. Chapter 1 of this volume…

Management of Obstructive Sleep Apnea in Commercial Motor Vehicle Operators: Recommendations of the AASM Sleep and Transportation Safety Awareness Task Force

PubMed Central

Gurubhagavatula, Indira; Sullivan, Shannon; Meoli, Amy; Patil, Susheel; Olson, Ryan; Berneking, Michael; Watson, Nathaniel F.

2017-01-01

The American Academy of Sleep Medicine Sleep and Transportation Safety Awareness Task Force responded to the Federal Motor Carrier Safety Administration and Federal Railroad Administration Advance Notice of Proposed Rulemaking and request for public comments regarding the evaluation of safety-sensitive personnel for moderate-to-severe obstructive sleep apnea (OSA). The following document represents this response. The most salient points provided in our comments are that (1) moderate-to-severe OSA is common among commercial motor vehicle operators (CMVOs) and contributes to an increased risk of crashes; (2) objective screening methods are available and preferred for identifying at-risk drivers, with the most commonly used indicator being body mass index; (3) treatment in the form of continuous positive airway pressure (CPAP) is effective and reduces crashes; (4) CPAP is economically viable; (5) guidelines are available to assist medical examiners in determining whether CMVOs with moderate-to-severe OSA should continue to work without restrictions, with conditional certification, or be disqualified from operating commercial motor vehicles. Citation: Gurubhagavatula I, Sullivan S, Meoli A, Patil S, Olson R, Berneking M, Watson NF. Management of obstructive sleep apnea in commercial motor vehicle operators: recommendations of the AASM Sleep and Transportation Safety Awareness Task Force. J Clin Sleep Med. 2017;13(5):745–758. PMID:28356173

The spatial epidemiology of cocaine, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) use: a demonstration using a population measure of community drug load derived from municipal wastewater.

PubMed

Banta-Green, Caleb J; Field, Jennifer A; Chiaia, Aurea C; Sudakin, Daniel L; Power, Laura; de Montigny, Luc

2009-11-01

To determine the utility of community-wide drug testing with wastewater samples as a population measure of community drug use and to test the hypothesis that the association with urbanicity would vary for three different stimulant drugs of abuse. Single-day samples were obtained from a convenience sample of 96 municipalities representing 65% of the population of the State of Oregon. Chemical analysis of 24-hour composite influent samples for benzoylecgonine (BZE, a cocaine metabolite), methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA). The distribution of community index drug loads accounting for total wastewater flow (i.e. dilution) and population are reported. The distribution of wastewater-derived drug index loads was found to correspond with expected epidemiological drug patterns. Index loads of BZE were significantly higher in urban areas and below detection in many rural areas. Conversely, methamphetamine was present in all municipalities, with no significant differences in index loads by urbanicity. MDMA was at quantifiable levels in fewer than half the communities, with a significant trend towards higher index loads in more urban areas. CONCLUSION; This demonstration provides the first evidence of the utility of wastewater-derived community drug loads for spatial analyses. Such data have the potential to improve dramatically the measurement of the true level and distribution of a range of drugs. Drug index load data provide information for all people in a community and are potentially applicable to a much larger proportion of the total population than existing measures.

Effects of height and load weight on shoulder muscle work during overhead lifting task.

PubMed

Blache, Y; Desmoulins, L; Allard, P; Plamondon, A; Begon, M

2015-01-01

Few musculoskeletal models are available to assess shoulder deeper muscle demand during overhead lifting tasks. Our objective was to implement a musculoskeletal model to assess the effect of lifting height and load on shoulder muscle work. A musculoskeletal model scaled from 15 male subjects was used to calculate shoulder muscle work during six lifting tasks. Boxes containing three different loads (6, 12 and 18 kg) were lifted by the subjects from the waist to shoulder or eye level. After optimisation of the maximal isometric force of the model's muscles, the bio-fidelity of the model was improved by 19%. The latter was able to reproduce the subjects' lifting movements. Mechanical work of the rotator cuff muscles, upper trapezius and anterior deltoid was increased with lifting load and height augmentation. In conclusion, the use of a musculoskeletal model validated by electromyography enabled to evaluate the muscle demand of deep muscles during lifting tasks.

Social anxiety under load: the effects of perceptual load in processing emotional faces.

PubMed

Soares, Sandra C; Rocha, Marta; Neiva, Tiago; Rodrigues, Paulo; Silva, Carlos F

2015-01-01

Previous studies in the social anxiety arena have shown an impaired attentional control system, similar to that found in trait anxiety. However, the effect of task demands on social anxiety in socially threatening stimuli, such as angry faces, remains unseen. In the present study, 54 university students scoring high and low in the Social Interaction and Performance Anxiety and Avoidance Scale (SIPAAS) questionnaire, participated in a target letter discrimination task while task-irrelevant face stimuli (angry, disgust, happy, and neutral) were simultaneously presented. The results showed that high (compared to low) socially anxious individuals were more prone to distraction by task-irrelevant stimuli, particularly under high perceptual load conditions. More importantly, for such individuals, the accuracy proportions for angry faces significantly differed between the low and high perceptual load conditions, which is discussed in light of current evolutionary models of social anxiety.

The Influence of Working Memory Load on Expectancy-Based Strategic Processes in the Stroop-Priming Task.

PubMed

Ortells, Juan J; Álvarez, Dolores; Noguera, Carmen; Carmona, Encarna; de Fockert, Jan W

2017-01-01

The present study investigated whether a differential availability of cognitive control resources as a result of varying working memory (WM) load could affect the capacity for expectancy-based strategic actions. Participants performed a Stroop-priming task in which a prime word (GREEN or RED) was followed by a colored target (red vs. green) that participants had to identify. The prime was incongruent or congruent with the target color on 80 and 20% of the trials, respectively, and participants were informed about the differential proportion of congruent vs. incongruent trials. This task was interleaved with a WM task, such that the prime word was preceded by a sequence of either a same digit repeated five times (low load) or five different random digits (high load), which should be retained by participants. After two, three, or four Stroop trials, they had to decide whether or not a probe digit was a part of the memory set. The key finding was a significant interaction between prime-target congruency and WM load: Whereas a strategy-dependent (reversed Stroop) effect was found under low WM load, a standard Stroop interference effect was observed under high WM load. These findings demonstrate that the availability of WM is crucial for implementing expectancy-based strategic actions.

Physical load handling and listening comprehension effects on balance control.

PubMed

Qu, Xingda

2010-12-01

The purpose of this study was to determine the physical load handling and listening comprehension effects on balance control. A total of 16 young and 16 elderly participants were recruited in this study. The physical load handling task required holding a 5-kg load in each hand with arms at sides. The listening comprehension task involved attentive listening to a short conversation. Three short questions were asked regarding the conversation right after the testing trial to test the participants' attentiveness during the experiment. Balance control was assessed by centre of pressure-based measures, which were calculated from the force platform data when the participants were quietly standing upright on a force platform. Results from this study showed that both physical load handling and listening comprehension adversely affected balance control. Physical load handling had a more deleterious effect on balance control under the listening comprehension condition vs. no-listening comprehension condition. Based on the findings from this study, interventions for the improvement of balance could be focused on avoiding exposures to physically demanding tasks and cognitively demanding tasks simultaneously. STATEMENT OF RELEVANCE: Findings from this study can aid in better understanding how humans maintain balance, especially when physical and cognitive loads are applied. Such information is useful for developing interventions to prevent fall incidents and injuries in occupational settings and daily activities.

Opposing effects of perceptual versus working memory load on emotional distraction.

PubMed

Tavares, Tamara P; Logie, Kyle; Mitchell, Derek G V

2016-10-01

Throughout our day-to-day activities, we are subjected to numerous stimuli that compete for our attention; consequently, we must prioritize stimuli for further processing and influence over behaviour. Previous research has demonstrated that the extent to which task-irrelevant distractors are processed is mediated by the nature of the cognitive task, and the level of processing load. Importantly though, the interaction between cognitive task, processing load, and emotional distractor processing remains unclear. This is a particularly important question given the unique ways that emotion interacts with attention, and the fact that some other forms of processing load have been shown to reduce emotional distractor encoding. In the present study, participants were presented with emotional distractors during a perceptual and working memory task, under varying levels of load. In Experiment 1, we showed that the impact of emotional distractors on behaviour was reduced under conditions of high relative to low perceptual load. However, in sharp contrast, high working memory load was associated with increased emotional distraction. Importantly, these results were replicated in Experiment 2. Overall, the impact of processing load on emotional distraction varies according to the cognitive function being performed. These results raise the intriguing possibility that working memory operations deplete some of the cognitive resources needed to control the impact of emotion on behaviour. The findings, therefore, may have important implications for clinical populations featuring cognitive dysfunction and emotional dysregulation.

Working memory activation of neural networks in the elderly as a function of information processing phase and task complexity.

PubMed

Charroud, Céline; Steffener, Jason; Le Bars, Emmanuelle; Deverdun, Jérémy; Bonafe, Alain; Abdennour, Meriem; Portet, Florence; Molino, François; Stern, Yaakov; Ritchie, Karen; Menjot de Champfleur, Nicolas; Akbaraly, Tasnime N

2015-11-01

Changes in working memory are sensitive indicators of both normal and pathological brain aging and associated disability. The present study aims to further understanding of working memory in normal aging using a large cohort of healthy elderly in order to examine three separate phases of information processing in relation to changes in task load activation. Using covariance analysis, increasing and decreasing neural activation was observed on fMRI in response to a delayed item recognition task in 337 cognitively healthy elderly persons as part of the CRESCENDO (Cognitive REServe and Clinical ENDOphenotypes) study. During three phases of the task (stimulation, retention, probe), increased activation was observed with increasing task load in bilateral regions of the prefrontal cortex, parietal lobule, cingulate gyrus, insula and in deep gray matter nuclei, suggesting an involvement of central executive and salience networks. Decreased activation associated with increasing task load was observed during the stimulation phase, in bilateral temporal cortex, parietal lobule, cingulate gyrus and prefrontal cortex. This spatial distribution of decreased activation is suggestive of the default mode network. These findings support the hypothesis of an increased activation in salience and central executive networks and a decreased activation in default mode network concomitant to increasing task load. Copyright © 2015 Elsevier Inc. All rights reserved.

Analysis of collaborative communication for linguistic cues of cognitive load.

PubMed

Khawaja, M Asif; Chen, Fang; Marcus, Nadine

2012-08-01

Analyses of novel linguistic and grammatical features, extracted from transcribed speech of people working in a collaborative environment, were performed for cognitive load measurement Prior studies have attempted to assess users' cognitive load with several measures, but most of them are intrusive and disrupt normal task flow. An effective measurement of people's cognitive load can help improve their performance by deploying appropriate output and support strategies accordingly. The authors studied 33 members of bushfire management teams working collaboratively in computerized incident control rooms and involved in complex bushfire management tasks. The participants' communication was analyzed for some novel linguistic features as potential indices of cognitive load, which included sentence length, use of agreement and disagreement phrases, and use of personal pronouns, including both singular and plural pronoun types. Results showed users' different linguistic and grammatical patterns with various cognitive load levels. Specifically, with high load, people spoke more and used longer sentences, used more words that indicated disagreement with other team members, and exhibited increased use of plural personal pronouns and decreased use of singular pronouns. The article provides encouraging evidence for the use of linguistic and grammatical analysis for measuring users' cognitive load and proposes some novel features as cognitive load indices. The proposed approach may be applied to many data-intense and safety-critical task scenarios, such as emergency management departments, for example, bushfire or traffic incident management centers; air traffic control rooms; and call centers, where speech is used as part of everyday tasks.

Measuring Cognitive Load during Simulation-Based Psychomotor Skills Training: Sensitivity of Secondary-Task Performance and Subjective Ratings

ERIC Educational Resources Information Center

Haji, Faizal A.; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

2015-01-01

As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance…

Luteolin-loaded solid lipid nanoparticles synthesis, characterization, & improvement of bioavailability, pharmacokinetics in vitro and vivo studies

NASA Astrophysics Data System (ADS)

Dang, Hao; Meng, Murtaza Hasan Weiwei; Zhao, Haiwei; Iqbal, Javed; Dai, Rongji; Deng, Yulin; Lv, Fang

2014-04-01

Luteolin (LU, 5,7,3',4'-tetrahydroxyflavone) most active compound in Chinese herbal flavones has been acting as a antimicrobial, anti-inflammatory, anti-cancer, and antimutagen. However, its poor bioavailability, hydrophobicity, and pharmacokinetics restrict clinical application. Here in this study, LU-loaded solid lipid nanoparticles have been prepared by hot-microemulsion ultrasonic technique to improve the bioavailability & pharmacokinetics of compound. LU-loaded solid lipid nanoparticle size was confirmed by particle size analyzer with range from 47 to 118 nm, having zepta potential -9.2 mV and polydisperse index 0.247, respectively. Round-shaped SLNPs were obtained by using transmission electron microscope, and encapsulation efficiency 74.80 % was calculated by using HPLC. Both in vitro and vivo studies, LC-MS/MS technique was used for quantification of Luteolin in rat. The T max value of drug with LU-SLNs after the administration was Ten times shorter than pure Luteolin suspension administration. C max value of drug after the administration of LU-SLNs was five times higher than obtained with native drug suspension. Luteolin with SLNs has increased the half-life approximately up to 2 h. Distribution and clearance of drug with SLNs were significantly decreased by 2.16-10.57 fold, respectively. In the end, the relative bioavailability of SLNs has improved about 4.89 compared to Luteolin with SLNs. From this study, it can be concluded that LU-SLNs have not only great potential for improving solubility but also increased the drug concentration in plasma. Furthermore, use of LC-MS/MS for quantification of LU-SLNs in rat plasma is reliable and of therapeutic usefulness, especially for neurodegenerative and cancerous disorders in humans.

Numbers Are Associated with Different Types of Spatial Information Depending on the Task

ERIC Educational Resources Information Center

van Dijck, Jean-Philippe; Gevers, Wim; Fias, Wim

2009-01-01

In this study, we examined the nature of the spatial-numerical associations underlying the SNARC-effect by imposing a verbal or spatial working memory load during a parity judgment and a magnitude comparison task. The results showed a double dissociation between the type of working memory load and type of task. The SNARC-effect disappeared under…

Disengagement from tasks as a function of cognitive load and depressive symptom severity.

PubMed

Bowie, Christopher R; Milanovic, Melissa; Tran, Tanya; Cassidy, Sarah

2017-01-01

Depression is associated with impairment in cognition and everyday functioning. Mechanisms of cognitive dysfunction in depression and the factors that influence strategic deployment of cognitive abilities in complex environments remain elusive. In this study we investigated whether depression symptom severity is associated with disengagement from a working memory task (Paced Auditory Serial Addition Task; PASAT) with parametric adjustment of task difficulty. 235 participants completed the Beck Depression Inventory, low and high cognitive load conditions of the PASAT, and quality of life. Cognitive disengagement was the sum of consecutive items in which participants did not proffer a response to the trial. Individuals with higher depression severity showed more cognitive disengagement on the high but not low cognitive load trial of the PASAT; they did not differ in number of correct responses. Increased disengagement from the low to high cognitive load was associated with more impaired quality of life. Depression severity is associated with increased disengagement from tasks as difficulty increases. These findings suggest the importance of measuring how cognitive skills are avoided in complex environments in addition to considering performance accuracy. Individuals with depressive symptoms might preferentially avoid cognitive tasks that are perceived as more complex in spite of intact ability.

Assessment of thermal load on transported goats administered with ascorbic acid during the hot-dry conditions

NASA Astrophysics Data System (ADS)

Minka, N. S.; Ayo, J. O.

2012-03-01

The major factor in the induction of physiological stress during road transportation of livestock is the complex fluctuations of the thermal transport microenvironment, encountered when animals are transported across different ecological zones. Recommended guidelines on optimum "on-board" conditions in which goats should be transported are lacking, and there are no acceptable ranges and limits for the thermal loads to which goats may be subjected during long-distance road transportation in hot-dry conditions. Panting score (PS), rectal temperature (RT), heart rate (HR) and respiratory rate (RR) were employed as reliable stress indices to assess the effects of different thermal loads, measured as temperature humidity index (THI), encountered in the vehicle during 12 h of road transportation of 40 goats, and to suggest the administration of 100 mg/kg body weight of ascorbic acid (AA) as an ameliorating agent. The results obtained showed that the PS, RT, HR and RR rose above normal reference values with increase in the THI and journey duration. The rise in PS value, which is a visual indicator of the severity of thermal load, was the most pronounced. The results suggest that values of THI in the vehicle up to 94.6 constitute no risk, while at of 100 it presents a moderate risk and above 100 may result in severe stress. The relationships between the thermal load and the physiological variables were positive and significant ( P < 0.05). They reflect the degree of stress imposed by each THI value during the transportation, and may be used as recommended ranges and limit thermal load values in transported goats. The results demonstrated that administration of 100 mg/kg body weight of AA before road transportation mitigated the risk of adverse effects of high THI values and other stress factors due to road transportation in goats.

Lessons learned from the usability assessment of home-based telemedicine systems.

PubMed

Agnisarman, Sruthy Orozhiyathumana; Chalil Madathil, Kapil; Smith, Kevin; Ashok, Aparna; Welch, Brandon; McElligott, James T

2017-01-01

At-home telemedicine visits are quickly becoming an acceptable alternative for in-person patient visits. However, little work has been done to understand the usability of these home-based telemedicine solutions. It is critical for user acceptance and real-world applicability to evaluate available telemedicine solutions within the context-specific needs of the users of this technology. To address this need, this study evaluated the usability of four home-based telemedicine software platforms: Doxy.me, Vidyo, VSee, and Polycom. Using a within-subjects experimental design, twenty participants were asked to complete a telemedicine session involving several tasks using the four platforms. Upon completion of these tasks for each platform, participants completed the IBM computer system usability questionnaire (CSUQ) and the NASA Task Load Index test. Upon completing the tasks on all four platforms, the participants completed a final post-test subjective questionnaire ranking the platforms based on their preference. Of the twenty participants, 19 completed the study. Statistically significant differences among the telemedicine software platforms were found for task completion time, total workload, mental demand, effort, frustration, preference ranking and computer system usability scores. Usability problems with installation and account creation led to high mental demand and task completion time, suggesting the participants preferred a system without such requirements. Majority of the usability issues were identified at the telemedicine initiation phase. The findings from this study can be used by software developers to develop user-friendly telemedicine systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Domain-Specific Control of Selective Attention

PubMed Central

Lin, Szu-Hung; Yeh, Yei-Yu

2014-01-01

Previous research has shown that loading information on working memory affects selective attention. However, whether the load effect on selective attention is domain-general or domain-specific remains unresolved. The domain-general effect refers to the findings that load in one content (e.g. phonological) domain in working memory influences processing in another content (e.g., visuospatial) domain. Attentional control supervises selection regardless of information domain. The domain-specific effect refers to the constraint of influence only when maintenance and processing operate in the same domain. Selective attention operates in a specific content domain. This study is designed to resolve this controversy. Across three experiments, we manipulated the type of representation maintained in working memory and the type of representation upon which the participants must exert control to resolve conflict and select a target into the focus of attention. In Experiments 1a and 1b, participants maintained digits and nonverbalized objects, respectively, in working memory while selecting a target in a letter array. In Experiment 2, we presented auditory digits with a letter flanker task to exclude the involvement of resource competition within the same input modality. In Experiments 3a and 3b, we replaced the letter flanker task with an object flanker task while manipulating the memory load on object and digit representation, respectively. The results consistently showed that memory load modulated distractibility only when the stimuli of the two tasks were represented in the same domain. The magnitude of distractor interference was larger under high load than under low load, reflecting a lower efficacy of information prioritization. When the stimuli of the two tasks were represented in different domains, memory load did not modulate distractibility. Control of processing priority in selective attention demands domain-specific resources. PMID:24866977

THE RELATIONSHIP BETWEEN MEASURES OF IMPULSIVITY AND ALCOHOL MISUSE: AN INTEGRATIVE STRUCTURAL EQUATION MODELING APPROACH

PubMed Central

Courtney, Kelly E.; Arellano, Ryan; Barkley-Levenson, Emily; Gálvan, Adriana; Poldrack, Russell A.; MacKillop, James; Jentsch, J. David; Ray, Lara A.

2011-01-01

Background Higher levels of impulsivity have been implicated in the development of alcohol use disorders. Recent findings suggest that impulsivity is not a unitary construct, highlighted by the diverse ways in which the various measures of impulsivity relate to alcohol use outcomes. This study simultaneously tested the following dimensions of impulsivity as determinants of alcohol use and alcohol problems: risky decision-making, self-reported risk attitudes, response inhibition, and impulsive decision-making. Method Participants were a community sample of non-treatment seeking problem drinkers (N = 158). Structural Equation Modeling (SEM) analyses employed behavioral measures of impulsive decision-making (Delay Discounting Task, DDT), response inhibition (Stop Signal Task, SST), and risky decision-making (Balloon Analogue Risk Task, BART), and a self-report measure of risk attitudes (Domain-specific Risk-attitude Scale, DOSPERT), as predictors of alcohol use and of alcohol-related problems in this sample. Results The model fit well, accounting for 38% of the variance in alcohol problems, and identified two impulsivity dimensions that significantly loaded onto alcohol outcomes: (1) impulsive decision-making, indexed by the DDT; and (2) risky decision-making, measured by the BART. Conclusions The impulsive decision-making dimension of impulsivity, indexed by the DDT, was the strongest predictor of alcohol use and alcohol pathology in this sample of problem drinkers. Unexpectedly, a negative relationship was found between risky decision-making and alcohol problems. The results highlight the importance of considering the distinct facets of impulsivity in order to elucidate their individual and combined effects on alcohol use initiation, escalation, and dependence. PMID:22091877

Neuronal effects of auditory distraction on visual attention

PubMed Central

Smucny, Jason; Rojas, Donald C.; Eichman, Lindsay C.; Tregellas, Jason R.

2013-01-01

Selective attention in the presence of distraction is a key aspect of healthy cognition. The underlying neurobiological processes, have not, however, been functionally well characterized. In the present study, we used functional magnetic resonance imaging to determine how ecologically relevant distracting noise affects cortical activity in 27 healthy adults during two versions of the visual sustained attention to response task (SART) that differ in difficulty (and thus attentional load). A significant condition (noise or silence) by task (easy or difficult) interaction was observed in several areas, including dorsolateral prefrontal cortex (DLPFC), fusiform gyrus (FG), posterior cingulate (PCC), and pre-supplementary motor area (PreSMA). Post-hoc analyses of interaction effects revealed deactivation of DLPFC, PCC, and PreSMA during distracting noise under conditions of low attentional load, and activation of FG and PCC during distracting noise under conditions of high attentional load. These results suggest that distracting noise may help alert subjects to task goals and reduce demands on cortical resources during tasks of low difficulty and attentional load. Under conditions of higher load, however, additional cognitive resources may be required in the presence of noise. PMID:23291265

Divided attention disrupts perceptual encoding during speech recognition.

PubMed

Mattys, Sven L; Palmer, Shekeila D

2015-03-01

Performing a secondary task while listening to speech has a detrimental effect on speech processing, but the locus of the disruption within the speech system is poorly understood. Recent research has shown that cognitive load imposed by a concurrent visual task increases dependency on lexical knowledge during speech processing, but it does not affect lexical activation per se. This suggests that "lexical drift" under cognitive load occurs either as a post-lexical bias at the decisional level or as a secondary consequence of reduced perceptual sensitivity. This study aimed to adjudicate between these alternatives using a forced-choice task that required listeners to identify noise-degraded spoken words with or without the addition of a concurrent visual task. Adding cognitive load increased the likelihood that listeners would select a word acoustically similar to the target even though its frequency was lower than that of the target. Thus, there was no evidence that cognitive load led to a high-frequency response bias. Rather, cognitive load seems to disrupt sublexical encoding, possibly by impairing perceptual acuity at the auditory periphery.

Interface Stability Influences Torso Muscle Recruitment and Spinal Load During Pushing Tasks

PubMed Central

LEE, P. J.; GRANATA, K. P.

2006-01-01

Handle or interface design can influence torso muscle recruitment and spinal load during pushing tasks. The objective of the study was to provide insight into the role of interface stability with regard to torso muscle recruitment and biomechanical loads on the spine. Fourteen subjects generated voluntary isometric trunk flexion force against a rigid interface and similar flexion exertions against an unstable interface, which simulated handle design in a cart pushing task. Normalized electromyographic (EMG) activity in the rectus abdominus, external oblique and internal oblique muscles increased with exertion effort. When using the unstable interface, EMG activity in the internal and external oblique muscle groups was greater than when using the rigid interface. Results agreed with trends from a biomechanical model implemented to predict the muscle activation necessary to generate isometric pushing forces and maintain spinal stability when using the two different interface designs. The co-contraction contributed to increased spinal load when using the unstable interface. It was concluded that handle or interface design and stability may influence spinal load and associated risk of musculoskeletal injury during manual materials tasks that involve pushing exertions. PMID:16540437

Study on load forecasting to data centers of high power density based on power usage effectiveness

NASA Astrophysics Data System (ADS)

Zhou, C. C.; Zhang, F.; Yuan, Z.; Zhou, L. M.; Wang, F. M.; Li, W.; Yang, J. H.

2016-08-01

There is usually considerable energy consumption in data centers. Load forecasting to data centers is in favor of formulating regional load density indexes and of great benefit to getting regional spatial load forecasting more accurately. The building structure and the other influential factors, i.e. equipment, geographic and climatic conditions, are considered for the data centers, and a method to forecast the load of the data centers based on power usage effectiveness is proposed. The cooling capacity of a data center and the index of the power usage effectiveness are used to forecast the power load of the data center in the method. The cooling capacity is obtained by calculating the heat load of the data center. The index is estimated using the group decision-making method of mixed language information. An example is given to prove the applicability and accuracy of this method.

Cognitive Load Theory: implications for medical education: AMEE Guide No. 86.

PubMed

Young, John Q; Van Merrienboer, Jeroen; Durning, Steve; Ten Cate, Olle

2014-05-01

Cognitive Load Theory (CLT) builds upon established models of human memory that include the subsystems of sensory, working and long-term memory. Working memory (WM) can only process a limited number of information elements at any given time. This constraint creates a "bottleneck" for learning. CLT identifies three types of cognitive load that impact WM: intrinsic load (associated with performing essential aspects of the task), extraneous load (associated with non-essential aspects of the task) and germane load (associated with the deliberate use of cognitive strategies that facilitate learning). When the cognitive load associated with a task exceeds the learner's WM capacity, performance and learning is impaired. To facilitate learning, CLT researchers have developed instructional techniques that decrease extraneous load (e.g. worked examples), titrate intrinsic load to the developmental stage of the learner (e.g. simplify task without decontextualizing) and ensure that unused WM capacity is dedicated to germane load, i.e. cognitive learning strategies. A number of instructional techniques have been empirically tested. As learners' progress, curricula must also attend to the expertise-reversal effect. Instructional techniques that facilitate learning among early learners may not help and may even interfere with learning among more advanced learners. CLT has particular relevance to medical education because many of the professional activities to be learned require the simultaneous integration of multiple and varied sets of knowledge, skills and behaviors at a specific time and place. These activities possess high "element interactivity" and therefore impose a cognitive load that may surpass the WM capacity of the learner. Applications to various medical education settings (classroom, workplace and self-directed learning) are explored.

The role of strength and power during performance of high intensity military tasks under heavy load carriage.

PubMed

Mala, Jesse; Szivak, Tunde K; Flanagan, Shawn D; Comstock, Brett A; Laferrier, Justin Z; Maresh, Carl M; Kraemer, William J

2015-01-01

Previous research has investigated the physiological determinants of heavy load carriage while performing medium to long distance road marching, yet research examining the physiological underpinnings of high-intensity battlefield tasks is limited. This study sought to examine the role of strength and power during high-intensity combat tasks under heavy load carriage. Eighteen recreationally trained men (mean±SD: age, 21±2 years; height, 172±6 cm; weight, 80±13 kg) participated in this study and performed an anaerobic combat course under 2 randomized experimental conditions; unloaded and loaded. Subjects performed 3 trials under each condition on separate days, with a 5-minute rest between each trial. In the unloaded trial, subjects wore a uniform with boots weighing approximately 3.2 kg. During the loaded trial, in addition to the uniform and boots, subjects wore Interceptor body armor (6.94 kg-9.10 kg) and a MOLLE rucksack weighing 30 kg. The course consisted of 3 consecutive tasks, which began from the prone position, led into a 30 m sprint, followed by a 27 m zigzag run, and ended with a 10 m casualty drag weighing approximately 79.4 kg. Pearson correlations showed significant (P≤.05) strong correlations between lower body strength (r=-0.63, -0.62), lower body power (r=-0.67, -0.67) and upper body strength (r=-0.60, -0.62) and overall performance times in the unloaded and loaded condition, respectively. Strength and power are strongly related to high-intensity military tasks with and without heavy load carriage.

The influence of gender-specific loading patterns of the stop-jump task on anterior cruciate ligament strain.

PubMed

Weinhold, Paul S; Stewart, Jason-Dennis N; Liu, Hsin-Yi; Lin, Cheng-Feng; Garrett, William E; Yu, Bing

2007-08-01

Studies have shown that women are at higher risk of sustaining noncontact anterior cruciate ligament (ACL) injuries in specific sports. Recent gait studies of athletic tasks have documented that gender differences in knee movement, muscle activation, and external loading patterns exist. The objective of this study was to determine in a knee cadaver model if application of female-specific loading and movement patterns characterised in vivo for a stop-jump task cause higher ACL strains than male patterns. Gender-specific loading patterns of the landing phase of the vertical stop-jump task were applied to seven cadaver knees using published kinetic/kinematic results for recreational athletes. Loads applied consecutively included: tibial compression, quadriceps, hamstrings, external posterior tibial shear, and tibial torque. Knee flexion was fixed based on the kinematic data. Strain of the ACL was monitored by means of a differential variable reluctance transducer installed on the anterior-medial bundle of the ACL. The ACL strain was significantly increased (P<0.05) for the female loading pattern relative to the male loading pattern after the posterior tibial shear force was applied, and showed a similar trend (P=0.1) to be increased after the final tibial torque was applied. This study suggests that female motor control strategies used during the stop-jump task may place higher strains on the ACL than male strategies, thus putting females at greater risk of ACL injury. We believe these results suggest the potential effectiveness of using training programs to modify motor control strategies and thus modify the risk of injury.

Protective Effect of Astaxanthin on Vocal Fold Injury and Inflammation Due to Vocal Loading: A Clinical Trial.

PubMed

Kaneko, Mami; Kishimoto, Yo; Suzuki, Ryo; Kawai, Yoshitaka; Tateya, Ichiro; Hirano, Shigeru

2017-05-01

Professional voice users, such as singers and teachers, are at greater risk of developing vocal fold injury from excessive use of voice; thus, protection of the vocal fold is essential. One of the most important factors that aggravates injury is the production of reactive oxygen species at the wound site. The purpose of the current study was to assess the effect of astaxanthin, a strong antioxidant, on the protection of the vocal fold from injury and inflammation due to vocal loading. This study is an institutional review board-approved human clinical trial. Ten male subjects underwent a 60-minute vocal loading session and received vocal assessments prior to, immediately after, and 30 minutes postvocal loading (AST(-) status). All subjects were then prescribed 24 mg/day of astaxanthin for 28 days, after which they received the same vocal task and assessments (AST(+) status). Phonatory parameters were compared between both groups. Aerodynamic assessment, acoustic analysis, and GRBAS scale (grade, roughness, breathiness, asthenia, and strain) were significantly worse in the AST(-) status immediately after vocal loading, but improved by 30 minutes after loading. In contrast, none of the phonatory parameters in the AST(+) status were statistically worse, even when measured immediately after vocal loading. No allergic responses or adverse effects were observed after administration of astaxanthin. The current results suggest that astaxanthin can protect the vocal fold from injury and inflammation caused by vocal loading possibly through the regulation of oxidative stress. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Low Probability Tail Event Analysis and Mitigation in BPA Control Area: Task 2 Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Shuai; Makarov, Yuri V.; McKinstry, Craig A.

Task report detailing low probability tail event analysis and mitigation in BPA control area. Tail event refers to the situation in a power system when unfavorable forecast errors of load and wind are superposed onto fast load and wind ramps, or non-wind generators falling short of scheduled output, causing the imbalance between generation and load to become very significant.

Glucose administration prior to a divided attention task improves tracking performance but not word recognition: evidence against differential memory enhancement?

PubMed

Scholey, Andrew B; Sünram-Lea, Sandra I; Greer, Joanna; Elliott, Jade; Kennedy, David O

2009-01-01

The cognition-enhancing effects of glucose administration to humans have been well-documented; however, it remains unclear whether this effect preferentially targets episodic memory or other cognitive domains. The effect of glucose on the allocation of attentional resources during memory encoding was assessed using a sensitive dual-attention paradigm. One hundred and twenty volunteers (mean age 21.60, SD 4.89, 77 females) took part in this randomised, double-blind, placebo-controlled, parallel groups study where each consumed a 25-g glucose drink or a placebo. Half of the participants in each drink condition attempted to track a moving on-screen target during auditory word presentation. The distance between the cursor and the tracking target was used as an index of attentional cost during encoding. Effects of drink and tracking on recognition memory and drink on tracking performance were assessed. Self-rated appetite and mood were co-monitored. Co-performing the tracking task significantly impaired memory performance irrespective of drink condition. In the placebo-tracking condition, there was a cost to tracking manifest as greater deviation from target during and immediately following word presentation. Compared with placebo, the glucose drink significantly improved tracking performance during encoding. There were significant time-related changes in thirst and alertness ratings but these were not differentially affected by drink or tracking conditions. Tracking but not memory was enhanced by glucose. This finding suggests that, under certain task conditions, glucose administrations does not preferentially enhance memory performance. One mechanism through which glucose acts as a cognition enhancer is through allowing greater allocation of attentional resources.

Modeling Operator Performance in Low Task Load Supervisory Domains

DTIC Science & Technology

2011-06-01

PDF Probability Distribution Function SAFE System for Aircrew Fatigue Evaluation SAFTE Sleep , Activity, Fatigue, and Task Effectiveness SCT...attentional capacity due to high mental workload. In low task load settings, fatigue is mainly caused by lack of sleep and boredom experienced by...performance decrements. Also, psychological fatigue is strongly correlated with lack of sleep . Not surprisingly, operators of the morning shift reported the

75 FR 43565 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-26

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice: (10-084)] NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION... amended, the National Aeronautics and Space Administration announces a two-part meeting of the Ad-Hoc Task...

75 FR 33838 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-15

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice (10-065)] NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION... amended, the National Aeronautics and Space Administration announces a meeting of the Ad-Hoc Task Force on...

75 FR 15742 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-30

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice: (10-035)] NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION... amended, the National Aeronautics and Space Administration announces a meeting of the Ad-Hoc Task Force on...

Asymmetric Spatial Processing Under Cognitive Load

PubMed Central

Naert, Lien; Bonato, Mario; Fias, Wim

2018-01-01

Spatial attention allows us to selectively process information within a certain location in space. Despite the vast literature on spatial attention, the effect of cognitive load on spatial processing is still not fully understood. In this study we added cognitive load to a spatial processing task, so as to see whether it would differentially impact upon the processing of visual information in the left versus the right hemispace. The main paradigm consisted of a detection task that was performed during the maintenance interval of a verbal working memory task. We found that increasing cognitive working memory load had a more negative impact on detecting targets presented on the left side compared to those on the right side. The strength of the load effect correlated with the strength of the interaction on an individual level. The implications of an asymmetric attentional bias with a relative disadvantage for the left (vs the right) hemispace under high verbal working memory (WM) load are discussed. PMID:29740371

Deliberation's blindsight: how cognitive load can improve judgments.

PubMed

Hoffmann, Janina A; von Helversen, Bettina; Rieskamp, Jörg

2013-06-01

Multitasking poses a major challenge in modern work environments by putting the worker under cognitive load. Performance decrements often occur when people are under high cognitive load because they switch to less demanding--and often less accurate--cognitive strategies. Although cognitive load disturbs performance over a wide range of tasks, it may also carry benefits. In the experiments reported here, we showed that judgment performance can increase under cognitive load. Participants solved a multiple-cue judgment task in which high performance could be achieved by using a similarity-based judgment strategy but not by using a more demanding rule-based judgment strategy. Accordingly, cognitive load induced a shift to a similarity-based judgment strategy, which consequently led to more accurate judgments. By contrast, shifting to a similarity-based strategy harmed judgments in a task best solved by using a rule-based strategy. These results show how important it is to consider the cognitive strategies people rely on to understand how people perform in demanding work environments.

A Modification to the Computer Generated Acquisition Documents System (CGADS) for Microcomputer Use in a Program Office Environment.

DTIC Science & Technology

1985-09-01

FILL. MOVE ALPHA-RESPONSE TO RESPONSE. 221C-RUN-TASKS-EXIT. EXIT. 2220-DISPLAY-TASK-MENU. PERFORM 5000- OETER -NISC-TASK-VALS. MOVE 1 TO ANSWER-FILE-KEY...INDEX-FIELD-2 ELSE MOVE 4 TO ANSWER-FILE-KEY SUBTRACT 200 FROM INDEX-FIELD-2. 5000- OETER -MISC-TASK-VALS. IF AREA-NUMBER a ŕ" MOVE 1 TO TASK-FILE-REC-NUM

Using Functional Near-Infrared Spectroscopy to Measure Effects of Delta 9-Tetrahydrocannabinol on Prefrontal Activity and Working Memory in Cannabis Users.

PubMed

Keles, Hasan O; Radoman, Milena; Pachas, Gladys N; Evins, A Eden; Gilman, Jodi M

2017-01-01

Intoxication from cannabis impairs cognitive performance, in part due to the effects of Δ9-tetrahydrocannabinol (THC, the primary psychoactive compound in cannabis) on prefrontal cortex (PFC) function. However, a relationship between impairment in cognitive functioning with THC administration and THC-induced change in hemodynamic response has not been demonstrated. We explored the feasibility of using functional near-infrared spectroscopy (fNIRS) to examine the functional changes of the human PFC associated with cannabis intoxication and cognitive impairment. Eighteen adult regular cannabis users (final sample, n = 13) performed a working memory task ( n -back) during fNIRS recordings, before and after receiving a single dose of oral synthetic THC (dronabinol; 20-50 mg). Functional data were collected using a continuous-wave NIRS device, in which 8 Sources and 7 detectors were placed on the forehead, resulting in 20 channels covering PFC regions. Physiological changes and subjective intoxication measures were collected. We found a significant increase in the oxygenated hemoglobin (HbO) concentration after THC administration in several channels on the PFC during both the high working memory load (2-back) and the low working memory load (0-back) condition. The increased HbO response was accompanied by a trend toward an increased number of omission errors after THC administration. The current study suggests that cannabis intoxication is associated with increases in hemodynamic blood flow to the PFC, and that this increase can be detected with fNIRS.

Space Station Freedom (SSF) Data Management System (DMS) performance model data base

NASA Technical Reports Server (NTRS)

Stovall, John R.

1993-01-01

The purpose of this document was originally to be a working document summarizing Space Station Freedom (SSF) Data Management System (DMS) hardware and software design, configuration, performance and estimated loading data from a myriad of source documents such that the parameters provided could be used to build a dynamic performance model of the DMS. The document is published at this time as a close-out of the DMS performance modeling effort resulting from the Clinton Administration mandated Space Station Redesign. The DMS as documented in this report is no longer a part of the redesigned Space Station. The performance modeling effort was a joint undertaking between the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) Flight Data Systems Division (FDSD) and the NASA Ames Research Center (ARC) Spacecraft Data Systems Research Branch. The scope of this document is limited to the DMS core network through the Man Tended Configuration (MTC) as it existed prior to the 1993 Clinton Administration mandated Space Station Redesign. Data is provided for the Standard Data Processors (SDP's), Multiplexer/Demultiplexers (MDM's) and Mass Storage Units (MSU's). Planned future releases would have added the additional hardware and software descriptions needed to describe the complete DMS. Performance and loading data through the Permanent Manned Configuration (PMC) was to have been included as it became available. No future releases of this document are presently planned pending completion of the present Space Station Redesign activities and task reassessment.

Migration impact on load balancing - an experience on Amoeba

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, W.; Socko, P.

1996-12-31

Load balancing has been extensive study by simulation, positive results were received in most of the researches. With the increase of the availability oftlistributed systems, a few experiments have been carried out on different systems. These experimental studies either depend on task initiation or task initiation plus task migration. In this paper, we present the results of an 0 study of load balancing using a centralizedpolicy to manage the load on a set of processors, which was carried out on an Amoeba system which consists of a set of 386s and linked by 10 Mbps Ethernet. The results on onemore » hand indicate the necessity of a load balancing facility for a distributed system. On the other hand, the results question the impact of using process migration to increase system performance under the configuration used in our experiments.« less

The impact of occupational load carriage on carrier mobility: a critical review of the literature.

PubMed

Carlton, Simon D; Orr, Robin M

2014-01-01

Military personnel and firefighters are required to carry occupational loads and complete tasks in hostile and unpredictable environments where a lack of mobility may risk lives. This review critically examines the literature investigating the impacts of load carriage on the mobility of these specialist personnel. Several literature databases, reference lists, and subject matter experts were employed to identify relevant studies. Studies meeting the inclusion criteria were critiqued using the Downs and Black protocol. Inter-rater agreement was determined by Cohen's κ. Twelve original research studies, which included male and female participants from military and firefighting occupations, were critiqued (κ = .81). A review of these papers found that as the carried load weight increased, carrier mobility during aerobic tasks (like road marching) and anaerobic tasks (like obstacle course negotiation) decreased. As such, it can be concluded that the load carried by some specialist personnel may increase their occupational risk by reducing their mobility.

Age-Related Differences in the Reliance on Executive Control in Working Memory: Role of Task Demand

PubMed Central

Isingrini, Michel; Angel, Lucie; Fay, Séverine; Taconnat, Laurence; Lemaire, Patrick; Bouazzaoui, Badiâa

2015-01-01

We examined the hypothesis that age-related differences in the reliance on executive control may be better explained by variations of task demand than by a mechanism specifically linked to aging. To this end, we compared the relationship between the performance of young and older adults on two executive functioning tests and an updating working-memory task with different load levels. The results revealed a significant interaction between age, task demand, and individual executive capacities, indicating that executive resources were only involved at lower loads in older adults, and only at higher loads in young adults. Overall, the results are not consistent with the proposition that cognition places greater demand on executive control in older adults. However, they support the view that how much young and older adults rely on executive control to accomplish cognitive tasks depends on task demand. Finally, interestingly these results are consistent with the CRUNCH model accounting for age-related differences in brain activations. PMID:26700019

No Evidence for Inhibitory Deficits or Altered Reward Processing in ADHD: Data From a New Integrated Monetary Incentive Delay Go/No-Go Task.

PubMed

Demurie, Ellen; Roeyers, Herbert; Wiersema, Jan R; Sonuga-Barke, Edmund

2016-04-01

Cognitive and motivational factors differentially affect individuals with mental health problems such as ADHD. Here we introduce a new task to disentangle the relative contribution of inhibitory control and reward anticipation on task performance in children with ADHD and/or autism spectrum disorders (ASD). Typically developing children, children with ADHD,  ASD, or both disorders worked during separate sessions for monetary or social rewards in go/no-go tasks with varying inhibitory load levels. Participants also completed a monetary temporal discounting (TD) task. As predicted, task performance was sensitive to both the effects of anticipated reward amount and inhibitory load. Reward amount had different effects depending on inhibitory load level. TD correlated with inhibitory control in the ADHD group. The integration of the monetary incentive delay and go/no-go paradigms was successful. Surprisingly, there was no evidence of inhibitory control deficits or altered reward anticipation in the clinical groups. © The Author(s) 2013.

Age-Related Differences in the Reliance on Executive Control in Working Memory: Role of Task Demand.

PubMed

Isingrini, Michel; Angel, Lucie; Fay, Séverine; Taconnat, Laurence; Lemaire, Patrick; Bouazzaoui, Badiâa

2015-01-01

We examined the hypothesis that age-related differences in the reliance on executive control may be better explained by variations of task demand than by a mechanism specifically linked to aging. To this end, we compared the relationship between the performance of young and older adults on two executive functioning tests and an updating working-memory task with different load levels. The results revealed a significant interaction between age, task demand, and individual executive capacities, indicating that executive resources were only involved at lower loads in older adults, and only at higher loads in young adults. Overall, the results are not consistent with the proposition that cognition places greater demand on executive control in older adults. However, they support the view that how much young and older adults rely on executive control to accomplish cognitive tasks depends on task demand. Finally, interestingly these results are consistent with the CRUNCH model accounting for age-related differences in brain activations.

FAQs about the wireless challenge in healthcare.

PubMed

2014-01-01

AAMI's Wireless Strategy Task Force (WSTF) developed the following document to provide answers to frequently asked questions (FAQs) regarding wireless issues in the healthcare environment. A special thanks to Steve Baker, senior principal engineer at Welch Allyn, for leading the project and writing much of the content; as well as to Rick Hampton, wireless communications manager at Partners HealthCare Systems, Scott Coleman at Welch Allyn, and Paul Sherman, a consultant retired from the Veteran's Administration, who developed responses to many of the questions. The complete list of FAQs can be accessed at www.aami.org/hottopics/wireless/index.html .

Evaluation of 16 measures of mental workload using a simulated flight task emphasizing mediational activity

NASA Technical Reports Server (NTRS)

Wierwille, W. W.; Rahimi, M.; Casali, J. G.

1985-01-01

As aircraft and other systems become more automated, a shift is occurring in human operator participation in these systems. This shift is away from manual control and toward activities that tap the higher mental functioning of human operators. Therefore, an experiment was performed in a moving-base flight simulator to assess mediational (cognitive) workload measurement. Specifically, 16 workload estimation techniques were evaluated as to their sensitivity and intrusion in a flight task emphasizing mediational behavior. Task loading, using navigation problems presented on a display, was treated as an independent variable, and workload-measure values were treated as dependent variables. Results indicate that two mediational task measures, two rating scale measures, time estimation, and two eye behavior measures were reliably sensitive to mediational loading. The time estimation measure did, however, intrude on mediational task performance. Several of the remaining measures were completely insensitive to mediational load.

Mental juggling: when does multitasking impair reading comprehension?

PubMed

Cho, Kit W; Altarriba, Jeanette; Popiel, Maximilian

2015-01-01

The present study investigated the conditions under which multitasking impairs reading comprehension. Participants read prose passages (the primary task), some of which required them to perform a secondary task. In Experiment 1, we compared two different types of secondary tasks (answering trivia questions and solving math problems). Reading comprehension was assessed using a multiple-choice test that measured both factual and conceptual knowledge. The results showed no observable detrimental effects associated with multitasking. In Experiment 2, the secondary task was a cognitive load task that required participants to remember a string of numbers while reading the passages. Performance on the reading comprehension test was lower in the cognitive load conditions relative to the no-load condition. The present study delineates the conditions under which multitasking can impair or have no effect on reading comprehension. These results further our understanding of our capacity to multitask and have practical implications in our technologically advanced society in which multitasking has become commonplace.

Temporal production and visuospatial processing.

PubMed

Benuzzi, Francesca; Basso, Gianpaolo; Nichelli, Paolo

2005-12-01

Current models of prospective timing hypothesize that estimated duration is influenced either by the attentional load or by the short-term memory requirements of a concurrent nontemporal task. In the present study, we addressed this issue with four dual-task experiments. In Exp. 1, the effect of memory load on both reaction time and temporal production was proportional to the number of items of a visuospatial pattern to hold in memory. In Exps. 2, 3, and 4, a temporal production task was combined with two visual search tasks involving either pre-attentive or attentional processing. Visual tasks interfered with temporal production: produced intervals were lengthened proportionally to the display size. In contrast, reaction times increased with display size only when a serial, effortful search was required. It appears that memory and perceptual set size, rather than nonspecific attentional or short-term memory load, can influence prospective timing.

The Role of Cognitive Load in Intentional Forgetting Using the Think/No-Think Task.

PubMed

Noreen, Saima; de Fockert, Jan W

2017-01-01

We investigated the role of cognitive control in intentional forgetting by manipulating working memory load during the think/no-think task. In two experiments, participants learned a series of cue-target word pairs and were asked to recall the target words associated with some cues or to avoid thinking about the target associated with other cues. In addition to this, participants also performed a modified version of the n-back task which required them to respond to the identity of a single target letter present in the currently presented cue word (n = 0 condition, low working memory load), and in either the previous cue word (n = 1 condition, high working memory load, Experiment 1) or the cue word presented two trials previously (n = 2 condition, high working memory load, Experiment 2). Participants' memory for the target words was subsequently tested using same and novel independent probes. In both experiments it was found that although participants were successful at forgetting on both the same and independent-probe tests in the low working memory load condition, they were only successful at forgetting on the same-probe test in the high working memory load condition. We argue that our findings suggest that the high load working memory task diverted attention from direct suppression and acted as an interference-based strategy. Thus, when cognitive resources are limited participants can switch between the strategies they use to prevent unwanted memories from coming to mind.

Attentional load attenuates synaesthetic priming effects in grapheme-colour synaesthesia.

PubMed

Mattingley, Jason B; Payne, Jonathan M; Rich, Anina N

2006-02-01

One of the hallmarks of grapheme-colour synaesthesia is that colours induced by letters, digits and words tend to interfere with the identification of coloured targets when the two colours are different, i.e., when they are incongruent. In a previous investigation (Mattingley et al., 2001) we found that this synaesthetic congruency effect occurs when an achromatic-letter prime precedes a coloured target, but that the effect disappears when the letter is pattern masked to prevent conscious recognition of its identity. Here we investigated whether selective attention modulates the synaesthetic congruency effect in a letter-priming task. Fourteen grapheme-colour synaesthetes and 14 matched, non-synaesthetic controls participated. The amount of selective attention available to process the letter-prime was limited by having participants perform a secondary visual task that involved discriminating pairs of gaps in adjacent limbs of a diamond surrounding the prime. In separate blocks of trials the attentional load of the secondary task was systematically varied to yield 'low load' and 'high load' conditions. We found a significant congruency effect for synaesthetes, but not for controls, when they performed a secondary attention-demanding task during presentation of the letter prime. Crucially, however, the magnitude of this priming was significantly reduced under conditions of high-load relative to low-load, indicating that attention plays an important role in modulating synaesthesia. Our findings help to explain the observation that synaesthetic colour experiences are often weak or absent during attention-demanding tasks.

Clinical peripherality: development of a peripherality index for rural health services.

PubMed

Swan, Gillian M; Selvaraj, Sivasubramaniam; Godden, David J

2008-01-25

The configuration of rural health services is influenced by geography. Rural health practitioners provide a broader range of services to smaller populations scattered over wider areas or more difficult terrain than their urban counterparts. This has implications for training and quality assurance of outcomes. This exploratory study describes the development of a "clinical peripherality" indicator that has potential application to remote and rural general practice communities for planning and research purposes. Profiles of general practice communities in Scotland were created from a variety of public data sources. Four candidate variables were chosen that described demographic and geographic characteristics of each practice: population density, number of patients on the practice list, travel time to nearest specialist led hospital and travel time to Health Board administrative headquarters. A clinical peripherality index, based on these variables, was derived using factor analysis. Relationships between the clinical peripherality index and services offered by the practices and the staff profile of the practices were explored in a series of univariate analyses. Factor analysis on the four candidate variables yielded a robust one-factor solution explaining 75% variance with factor loadings ranging from 0.83 to 0.89. Rural and remote areas had higher median values and a greater scatter of clinical peripherality indices among their practices than an urban comparison area. The range of services offered and the profile of staffing of practices was associated with the peripherality index. Clinical peripherality is determined by the nature of the practice and its location relative to secondary care and administrative and educational facilities. It has features of both gravity model-based and travel time/accessibility indicators and has the potential to be applied to training of staff for rural and remote locations and to other aspects of health policy and planning. It may assist planners in conceptualising the effects on general practices of centralising specialist clinical services or administrative and educational facilities.

Clinical peripherality: development of a peripherality index for rural health services

PubMed Central

Swan, Gillian M; Selvaraj, Sivasubramaniam; Godden, David J

2008-01-01

Background The configuration of rural health services is influenced by geography. Rural health practitioners provide a broader range of services to smaller populations scattered over wider areas or more difficult terrain than their urban counterparts. This has implications for training and quality assurance of outcomes. This exploratory study describes the development of a "clinical peripherality" indicator that has potential application to remote and rural general practice communities for planning and research purposes. Methods Profiles of general practice communities in Scotland were created from a variety of public data sources. Four candidate variables were chosen that described demographic and geographic characteristics of each practice: population density, number of patients on the practice list, travel time to nearest specialist led hospital and travel time to Health Board administrative headquarters. A clinical peripherality index, based on these variables, was derived using factor analysis. Relationships between the clinical peripherality index and services offered by the practices and the staff profile of the practices were explored in a series of univariate analyses. Results Factor analysis on the four candidate variables yielded a robust one-factor solution explaining 75% variance with factor loadings ranging from 0.83 to 0.89. Rural and remote areas had higher median values and a greater scatter of clinical peripherality indices among their practices than an urban comparison area. The range of services offered and the profile of staffing of practices was associated with the peripherality index. Conclusion Clinical peripherality is determined by the nature of the practice and its location relative to secondary care and administrative and educational facilities. It has features of both gravity model-based and travel time/accessibility indicators and has the potential to be applied to training of staff for rural and remote locations and to other aspects of health policy and planning. It may assist planners in conceptualising the effects on general practices of centralising specialist clinical services or administrative and educational facilities. PMID:18221533

The effects of memory load and stimulus relevance on the EEG during a visual selective memory search task: an ERP and ERD/ERS study.

PubMed

Gomarus, H Karin; Althaus, Monika; Wijers, Albertus A; Minderaa, Ruud B

2006-04-01

Psychophysiological correlates of selective attention and working memory were investigated in a group of 18 healthy children using a visually presented selective memory search task. Subjects had to memorize one (load1) or 3 (load3) letters (memory set) and search for these among a recognition set consisting of 4 letters only if the letters appeared in the correct (relevant) color. Event-related potentials (ERPs) as well as alpha and theta event-related synchronization and desynchronization (ERD/ERS) were derived from the EEG that was recorded during the task. In the ERP to the memory set, a prolonged load-related positivity was found. In response to the recognition set, effects of relevance were manifested in an early frontal positivity and a later frontal negativity. Effects of load were found in a search-related negativity within the attended category and a suppression of the P3-amplitude. Theta ERS was most pronounced for the most difficult task condition during the recognition set, whereas alpha ERD showed a load-effect only during memorization. The manipulation of stimulus relevance and memory load affected both ERP components and ERD/ERS. The present paradigm may supply a useful method for studying processes of selective attention and working memory and can be used to examine group differences between healthy controls and children showing psychopathology.

The influence of schizotypal traits on attention under high perceptual load.

PubMed

Stotesbury, Hanne; Gaigg, Sebastian B; Kirhan, Saim; Haenschel, Corinna

2018-03-01

Schizophrenia Spectrum Disorders (SSD) are known to be characterised by abnormalities in attentional processes, but there are inconsistencies in the literature that remain unresolved. This article considers whether perceptual resource limitations play a role in moderating attentional abnormalities in SSD. According to perceptual load theory, perceptual resource limitations can lead to attenuated or superior performance on dual-task paradigms depending on whether participants are required to process, or attempt to ignore, secondary stimuli. If SSD is associated with perceptual resource limitations, and if it represents the extreme end of an otherwise normally distributed neuropsychological phenotype, schizotypal traits in the general population should lead to disproportionate performance costs on dual-task paradigms as a function of the perceptual task demands. To test this prediction, schizotypal traits were quantified via the Schizotypal Personality Questionnaire (SPQ) in 74 healthy volunteers, who also completed a dual-task signal detection paradigm that required participants to detect central and peripheral stimuli across conditions that varied in the overall number of stimuli presented. The results confirmed decreasing performance as the perceptual load of the task increased. More importantly, significant correlations between SPQ scores and task performance confirmed that increased schizotypal traits, particularly in the cognitive-perceptual domain, are associated with greater performance decrements under increasing perceptual load. These results confirm that attentional difficulties associated with SSD extend sub-clinically into the general population and suggest that cognitive-perceptual schizotypal traits may represent a risk factor for difficulties in the regulation of attention under increasing perceptual load.

Mental workload measurement in operator control room using NASA-TLX

NASA Astrophysics Data System (ADS)

Sugarindra, M.; Suryoputro, M. R.; Permana, A. I.

2017-12-01

The workload, encountered a combination of physical workload and mental workload, is a consequence of the activities for workers. Central control room is one department in the oil processing company, employees tasked with monitoring the processing unit for 24 hours nonstop with a combination of 3 shifts in 8 hours. NASA-TLX (NASA Task Load Index) is one of the subjective mental workload measurement using six factors, namely the Mental demand (MD), Physical demand (PD), Temporal demand (TD), Performance (OP), Effort (EF), frustration levels (FR). Measurement of a subjective mental workload most widely used because it has a high degree of validity. Based on the calculation of the mental workload, there at 5 units (DTU, NPU, HTU, DIST and OPS) at the control chamber (94; 83.33; 94.67; 81, 33 and 94.67 respectively) that categorize as very high mental workload. The high level of mental workload on the operator in the Central Control Room is a requirement to have high accuracy, alertness and can make decisions quickly

Pupil diameter as predictor of cognitive load: A novel tool for geoscience education research

NASA Astrophysics Data System (ADS)

Mitra, R.; McNeal, K.

2015-12-01

Pupils can truly serve as windows to the mind. Since the early part of the last decade, pupillometry, the study of pupils in response to cognitive tasks, have gained traction in psychophysiological studies. Muscles of the iris work in tandem with the autonomic nervous system in response to light condition to either dilate or contract the pupil, usually between 2 to 7 mm. Along with this response to light conditions, the pupils also contract or dilate in response to emotional or mental response. Therefore, for a cognitive task, if the ambient brightness is controlled, pupil dilation reflects the cognitive load associated with the task. Simple tasks such as counting, memorizing, multiplying and visual searching have been found to have pupillometry profiles reflective of the cognitive load involved with such tasks. In this study, we investigate whether pupil diameter can be used for education research where tasks can be more complex. In particular, we look at two specific types of tasks common in geoscience and several other STEM fields: graph reading and spatial problem solving.

Automation trust and attention allocation in multitasking workspace.

PubMed

Karpinsky, Nicole D; Chancey, Eric T; Palmer, Dakota B; Yamani, Yusuke

2018-07-01

Previous research suggests that operators with high workload can distrust and then poorly monitor automation, which has been generally inferred from automation dependence behaviors. To test automation monitoring more directly, the current study measured operators' visual attention allocation, workload, and trust toward imperfect automation in a dynamic multitasking environment. Participants concurrently performed a manual tracking task with two levels of difficulty and a system monitoring task assisted by an unreliable signaling system. Eye movement data indicate that operators allocate less visual attention to monitor automation when the tracking task is more difficult. Participants reported reduced levels of trust toward the signaling system when the tracking task demanded more focused visual attention. Analyses revealed that trust mediated the relationship between the load of the tracking task and attention allocation in Experiment 1, an effect that was not replicated in Experiment 2. Results imply a complex process underlying task load, visual attention allocation, and automation trust during multitasking. Automation designers should consider operators' task load in multitasking workspaces to avoid reduced automation monitoring and distrust toward imperfect signaling systems. Copyright © 2018. Published by Elsevier Ltd.

The facilitative effects of glucose ingestion on memory retrieval in younger and older adults: is task difficulty or task domain critical?

PubMed

Riby, Leigh M; McMurtrie, Hazel; Smallwood, Jonathan; Ballantyne, Carrie; Meikle, Andrew; Smith, Emily

2006-02-01

The ingestion of a glucose-containing drink has been shown to improve cognitive performance, particularly memory functioning. However, it remains unclear as to the extent to which task domain and task difficulty moderate the glucose enhancement effect. The aim of this research was to determine whether boosts in performance are restricted to particular classes of memory (episodic v. semantic) or to tasks of considerable cognitive load. A repeated measures (25 g glucose v. saccharin), counterbalanced, double-blind design was used with younger and older adults. Participants performed a battery of episodic (e.g. paired associate learning) and semantic memory (e.g. category verification) tasks under low and high cognitive load. Electrophysiological measures (heart rate and galvanic skin response) of arousal and mental effort were also gathered. The results indicated that whilst glucose appeared to aid episodic remembering, cognitive load did not exaggerate the facilitative effect. For semantic memory, there was little evidence to suggest that glucose can boost semantic memory retrieval even when the load was manipulated. One exception was that glucose facilitated performance during the difficult category fluency task. Regardless, the present findings are consistent with the domain-specific account in which glucose acts primarily on the hippocampal region, which is known to support episodic memory. The possible contribution of the hippocampus in semantic memory processing is also discussed.

The complex interaction between anxiety and cognition: insight from spatial and verbal working memory

PubMed Central

Vytal, Katherine E.; Cornwell, Brian R.; Letkiewicz, Allison M.; Arkin, Nicole E.; Grillon, Christian

2013-01-01

Anxiety can be distracting, disruptive, and incapacitating. Despite problems with empirical replication of this phenomenon, one fruitful avenue of study has emerged from working memory (WM) experiments where a translational method of anxiety induction (risk of shock) has been shown to disrupt spatial and verbal WM performance. Performance declines when resources (e.g., spatial attention, executive function) devoted to goal-directed behaviors are consumed by anxiety. Importantly, it has been shown that anxiety-related impairments in verbal WM depend on task difficulty, suggesting that cognitive load may be an important consideration in the interaction between anxiety and cognition. Here we use both spatial and verbal WM paradigms to probe the effect of cognitive load on anxiety-induced WM impairment across task modality. Subjects performed a series of spatial and verbal n-back tasks of increasing difficulty (1, 2, and 3-back) while they were safe or at risk for shock. Startle reflex was used to probe anxiety. Results demonstrate that induced-anxiety differentially impacts verbal and spatial WM, such that low and medium-load verbal WM is more susceptible to anxiety-related disruption relative to high-load, and spatial WM is disrupted regardless of task difficulty. Anxiety impacts both verbal and spatial processes, as described by correlations between anxiety and performance impairment, albeit the effect on spatial WM is consistent across load. Demanding WM tasks may exert top-down control over higher-order cortical resources engaged by anxious apprehension, however high-load spatial WM may continue to experience additional competition from anxiety-related changes in spatial attention, resulting in impaired performance. By describing this disruption across task modalities, these findings inform current theories of emotion–cognition interactions and may facilitate development of clinical interventions that seek to target cognitive impairments associated with anxiety. PMID:23542914

High-performance metadata indexing and search in petascale data storage systems

NASA Astrophysics Data System (ADS)

Leung, A. W.; Shao, M.; Bisson, T.; Pasupathy, S.; Miller, E. L.

2008-07-01

Large-scale storage systems used for scientific applications can store petabytes of data and billions of files, making the organization and management of data in these systems a difficult, time-consuming task. The ability to search file metadata in a storage system can address this problem by allowing scientists to quickly navigate experiment data and code while allowing storage administrators to gather the information they need to properly manage the system. In this paper, we present Spyglass, a file metadata search system that achieves scalability by exploiting storage system properties, providing the scalability that existing file metadata search tools lack. In doing so, Spyglass can achieve search performance up to several thousand times faster than existing database solutions. We show that Spyglass enables important functionality that can aid data management for scientists and storage administrators.

Neural effects of cognitive control load on auditory selective attention

PubMed Central

Sabri, Merav; Humphries, Colin; Verber, Matthew; Liebenthal, Einat; Binder, Jeffrey R.; Mangalathu, Jain; Desai, Anjali

2014-01-01

Whether and how working memory disrupts or alters auditory selective attention is unclear. We compared simultaneous event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) responses associated with task-irrelevant sounds across high and low working memory load in a dichotic-listening paradigm. Participants performed n-back tasks (1-back, 2-back) in one ear (Attend ear) while ignoring task-irrelevant speech sounds in the other ear (Ignore ear). The effects of working memory load on selective attention were observed at 130-210 msec, with higher load resulting in greater irrelevant syllable-related activation in localizer-defined regions in auditory cortex. The interaction between memory load and presence of irrelevant information revealed stronger activations primarily in frontal and parietal areas due to presence of irrelevant information in the higher memory load. Joint independent component analysis of ERP and fMRI data revealed that the ERP component in the N1 time-range is associated with activity in superior temporal gyrus and medial prefrontal cortex. These results demonstrate a dynamic relationship between working memory load and auditory selective attention, in agreement with the load model of attention and the idea of common neural resources for memory and attention. PMID:24946314

78 FR 23970 - Interagency Task Force on Veterans Small Business Development

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-23

... SMALL BUSINESS ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force Meeting. SUMMARY: This document corrects the SBA's Interagency Task Force on Veterans Small Business Developments...

Commercial equipment loads: End-Use Load and Consumer Assessment Program (ELCAP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pratt, R.G.; Williamson, M.A.; Richman, E.E.

1990-07-01

The Office of Energy Resources of the Bonneville Power Administration is generally responsible for the agency's power and conservation resource planning. As associated responsibility which supports a variety of office functions is the analysis of historical trends in and determinants of energy consumption. The Office of Energy Resources' End-Use Research Section operates a comprehensive data collection program to provide pertinent information to support demand-side planning, load forecasting, and demand-side program development and delivery. Part of this on-going program is known as the End-Use Load and Consumer Assessment Program (ELCAP), an effort designed to collect electricity usage data through direct monitoringmore » of end-use loads in buildings. This program is conducted for Bonneville by the Pacific Northwest Laboratory. This report provides detailed information on electricity consumption of miscellaneous equipment from the commercial portion of ELCAP. Miscellaneous equipment includes all commercial end-uses except heating, ventilating, air conditioning, and central lighting systems. Some examples of end-uses covered in this report are office equipment, computers, task lighting, refrigeration, and food preparation. Electricity consumption estimates, in kilowatt-hours per square food per year, are provided for each end-use by building type. The following types of buildings are covered: office, retail, restaurant, grocery, warehouse, school, university, and hotel/motel. 6 refs., 35 figs., 12 tabs.« less

Relation of Dietary Glycemic Index and Glycemic Load to Coronary Artery Calcium in Asymptomatic Korean Adults.

PubMed

Choi, Yuni; Chang, Yoosoo; Ryu, Seungho; Cho, Juhee; Kim, Mi Kyung; Ahn, Younjhin; Lee, Jung Eun; Sung, Eunju; Kim, Boyoung; Ahn, Jiin; Kim, Chan-Won; Rampal, Sanjay; Zhao, Di; Zhang, Yiyi; Pastor-Barriuso, Roberto; Lima, Joao A C; Chung, Eun Chul; Shin, Hocheol; Guallar, Eliseo

2015-08-15

The relation between glycemic index, glycemic load, and subclinical coronary atherosclerosis is unknown. The aim of the study was to evaluate the associations between energy-adjusted glycemic index, glycemic load, and coronary artery calcium (CAC). This study was cross-sectional analysis of 28,429 asymptomatic Korean men and women (mean age 41.4 years) without a history of diabetes or cardiovascular disease. All participants underwent a health screening examination between March 2011 and April 2013, and dietary intake over the preceding year was estimated using a validated food frequency questionnaire. Cardiac computed tomography was used for CAC scoring. The prevalence of detectable CAC (CAC score >0) was 12.4%. In multivariable-adjusted models, the CAC score ratios (95% confidence intervals) comparing the highest to the lowest quintile of glycemic index and glycemic load were 1.74 (1.08 to 2.81; p trend = 0.03) and 3.04 (1.43 to 6.46; p trend = 0.005), respectively. These associations did not differ by clinical subgroups, including the participants at low cardiovascular risk. In conclusion, these findings suggest that high dietary glycemic index and glycemic load were associated with a greater prevalence and degree of CAC, with glycemic load having a stronger association. Copyright © 2015 Elsevier Inc. All rights reserved.

Preattentive representation of feature conjunctions for concurrent spatially distributed auditory objects.

PubMed

Takegata, Rika; Brattico, Elvira; Tervaniemi, Mari; Varyagina, Olga; Näätänen, Risto; Winkler, István

2005-09-01

The role of attention in conjoining features of an object has been a topic of much debate. Studies using the mismatch negativity (MMN), an index of detecting acoustic deviance, suggested that the conjunctions of auditory features are preattentively represented in the brain. These studies, however, used sequentially presented sounds and thus are not directly comparable with visual studies of feature integration. Therefore, the current study presented an array of spatially distributed sounds to determine whether the auditory features of concurrent sounds are correctly conjoined without focal attention directed to the sounds. Two types of sounds differing from each other in timbre and pitch were repeatedly presented together while subjects were engaged in a visual n-back working-memory task and ignored the sounds. Occasional reversals of the frequent pitch-timbre combinations elicited MMNs of a very similar amplitude and latency irrespective of the task load. This result suggested preattentive integration of auditory features. However, performance in a subsequent target-search task with the same stimuli indicated the occurrence of illusory conjunctions. The discrepancy between the results obtained with and without focal attention suggests that illusory conjunctions may occur during voluntary access to the preattentively encoded object representations.

Visual scanning behavior and pilot workload

NASA Technical Reports Server (NTRS)

Harris, R. L., Sr.; Tole, J. R.; Stephens, A. T.; Ephrath, A. R.

1982-01-01

This paper describes an experimental paradigm and a set of results which demonstrate a relationship between the level of performance on a skilled man-machine control task, the skill of the operator, the level of mental difficulty induced by an additional task imposed on the basic control task, and visual scanning performance. During a constant, simulated piloting task, visual scanning of instruments was found to vary with the difficulty of a verbal mental loading task. The average dwell time of each fixation on the pilot's primary instrument increased with the estimated skill level of the pilots, with novices being affected by the loading task much more than experts. The results suggest that visual scanning of instruments in a controlled task may be an indicator of both workload and skill.

A simple method for assessment of muscle force, velocity, and power producing capacities from functional movement tasks.

PubMed

Zivkovic, Milena Z; Djuric, Sasa; Cuk, Ivan; Suzovic, Dejan; Jaric, Slobodan

2017-07-01

A range of force (F) and velocity (V) data obtained from functional movement tasks (e.g., running, jumping, throwing, lifting, cycling) performed under variety of external loads have typically revealed strong and approximately linear F-V relationships. The regression model parameters reveal the maximum F (F-intercept), V (V-intercept), and power (P) producing capacities of the tested muscles. The aim of the present study was to evaluate the level of agreement between the routinely used "multiple-load model" and a simple "two-load model" based on direct assessment of the F-V relationship from only 2 external loads applied. Twelve participants were tested on the maximum performance vertical jumps, cycling, bench press throws, and bench pull performed against a variety of different loads. All 4 tested tasks revealed both exceptionally strong relationships between the parameters of the 2 models (median R = 0.98) and a lack of meaningful differences between their magnitudes (fixed bias below 3.4%). Therefore, addition of another load to the standard tests of various functional tasks typically conducted under a single set of mechanical conditions could allow for the assessment of the muscle mechanical properties such as the muscle F, V, and P producing capacities.

Trying to Put the Puzzle Together: Age and Performance Level Modulate the Neural Response to Increasing Task Load within Left Rostral Prefrontal Cortex.

PubMed

Bauer, Eva; Sammer, Gebhard; Toepper, Max

2015-01-01

Age-related working memory decline is associated with functional cerebral changes within prefrontal cortex (PFC). Kind and meaning of these changes are heavily discussed since they depend on performance level and task load. Hence, we investigated the effects of age, performance level, and load on spatial working memory retrieval-related brain activation in different subregions of the PFC. 19 younger (Y) and 21 older (O) adults who were further subdivided into high performers (HP) and low performers (LP) performed a modified version of the Corsi Block-Tapping test during fMRI. Brain data was analyzed by a 4 (groups: YHP, OHP, YLP, and OLP) × 3 (load levels: loads 4, 5, and 6) ANOVA. Results revealed significant group × load interaction effects within rostral dorsolateral and ventrolateral PFC. YHP showed a flexible neural upregulation with increasing load, whereas YLP reached a resource ceiling at a moderate load level. OHP showed a similar (though less intense) pattern as YHP and may have compensated age-effects at high task load. OLP showed neural inefficiency at low and no upregulation at higher load. Our findings highlight the relevance of age and performance level for load-dependent activation within rostral PFC. Results are discussed in the context of the compensation-related utilization of neural circuits hypothesis (CRUNCH) and functional PFC organization.

Curvilinear relationship between phonological working memory load and social-emotional modulation

PubMed Central

Mano, Quintino R.; Brown, Gregory G.; Bolden, Khalima; Aupperle, Robin; Sullivan, Sarah; Paulus, Martin P.; Stein, Murray B.

2015-01-01

Accumulating evidence suggests that working memory load is an important factor for the interplay between cognitive and facial-affective processing. However, it is unclear how distraction caused by perception of faces interacts with load-related performance. We developed a modified version of the delayed match-to-sample task wherein task-irrelevant facial distracters were presented early in the rehearsal of pseudoword memoranda that varied incrementally in load size (1-syllable, 2-syllables, or 3-syllables). Facial distracters displayed happy, sad, or neutral expressions in Experiment 1 (N=60) and happy, fearful, or neutral expressions in Experiment 2 (N=29). Facial distracters significantly disrupted task performance in the intermediate load condition (2-syllable) but not in the low or high load conditions (1- and 3-syllables, respectively), an interaction replicated and generalised in Experiment 2. All facial distracters disrupted working memory in the intermediate load condition irrespective of valence, suggesting a primary and general effect of distraction caused by faces. However, sad and fearful faces tended to be less disruptive than happy faces, suggesting a secondary and specific valence effect. Working memory appears to be most vulnerable to social-emotional information at intermediate loads. At low loads, spare capacity is capable of accommodating the combinatorial load (1-syllable plus facial distracter), whereas high loads maximised capacity and deprived facial stimuli from occupying working memory slots to cause disruption. PMID:22928750

The effects of concurrent cognitive load on phonological processing in adults who stutter.

PubMed

Jones, Robin M; Fox, Robert A; Jacewicz, Ewa

2012-12-01

To determine whether phonological processing in adults who stutter (AWS) is disrupted by increased amounts of cognitive load in a concurrent attention-demanding task. Nine AWS and 9 adults who do not stutter (AWNS) participated. Using a dual-task paradigm, the authors presented word pairs for rhyme judgments and, concurrently, letter strings for memory recall. The rhyme judgment task manipulated rhyming type (rhyming/nonrhyming) and orthographic representation (similar/dissimilar). The memory recall task varied stimulus complexity (no letters, 3 letters, 5 letters). Rhyme judgment accuracy and reaction time (RT) were used to assess phonological processing, and letter recall accuracy was used to measure memory recall. For rhyme judgments, AWS were as accurate as AWNS, and the increase in the cognitive load did not affect rhyme judgment accuracy of either group. Significant group differences were found in RTs (delays by AWS were 241 ms greater). RTs of AWS were also slower in the most demanding rhyme condition and varied with the complexity of the memory task. Accuracy of letter recall of AWS was comparatively worse in the most demanding 5-letter condition. Phonological and cognitive processing of AWS is more vulnerable to disruptions caused by increased amounts of cognitive load in concurrent attention-demanding tasks.

Cross-Modal Decoding of Neural Patterns Associated with Working Memory: Evidence for Attention-Based Accounts of Working Memory

PubMed Central

Majerus, Steve; Cowan, Nelson; Péters, Frédéric; Van Calster, Laurens; Phillips, Christophe; Schrouff, Jessica

2016-01-01

Recent studies suggest common neural substrates involved in verbal and visual working memory (WM), interpreted as reflecting shared attention-based, short-term retention mechanisms. We used a machine-learning approach to determine more directly the extent to which common neural patterns characterize retention in verbal WM and visual WM. Verbal WM was assessed via a standard delayed probe recognition task for letter sequences of variable length. Visual WM was assessed via a visual array WM task involving the maintenance of variable amounts of visual information in the focus of attention. We trained a classifier to distinguish neural activation patterns associated with high- and low-visual WM load and tested the ability of this classifier to predict verbal WM load (high–low) from their associated neural activation patterns, and vice versa. We observed significant between-task prediction of load effects during WM maintenance, in posterior parietal and superior frontal regions of the dorsal attention network; in contrast, between-task prediction in sensory processing cortices was restricted to the encoding stage. Furthermore, between-task prediction of load effects was strongest in those participants presenting the highest capacity for the visual WM task. This study provides novel evidence for common, attention-based neural patterns supporting verbal and visual WM. PMID:25146374

Hormonal modulation of novelty processing in women: Enhanced under working memory load with high dehydroepiandrosterone-sulfate-to-dehydroepiandrosterone ratios.

PubMed

do Vale, Sónia; Selinger, Lenka; Martins, João Martin; Bicho, Manuel; do Carmo, Isabel; Escera, Carles

2016-11-10

Several studies have suggested that dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulfate (DHEAS) may enhance working memory and attention, yet current evidence is still inconclusive. The balance between both forms of the hormone might be crucial regarding the effects that DHEA and DHEAS exert on the central nervous system. To test the hypothesis that higher DHEAS-to-DHEA ratios might enhance working memory and/or involuntary attention, we studied the DHEAS-to-DHEA ratio in relation to involuntary attention and working memory processing by recording the electroencephalogram of 22 young women while performing a working memory load task and a task without working memory load in an audio-visual oddball paradigm. DHEA and DHEAS were measured in saliva before each task. We found that a higher DHEAS-to-DHEA ratio was related to enhanced auditory novelty-P3 amplitudes during performance of the working memory task, indicating an increased processing of the distracter, while on the other hand there was no difference in the processing of the visual target. These results suggest that the balance between DHEAS and DHEA levels modulates involuntary attention during the performance of a task with cognitive load without interfering with the processing of the task-relevant visual stimulus. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Autonomic nervous system correlates to readiness state and negative outcome during visual discrimination tasks.

PubMed

Salvia, Emilie; Guillot, Aymeric; Collet, Christian

2012-05-01

Decision-making in daily activities require different levels of mental load depending on both objective task requirements and self-perception of task constraints. Such factors elicit strain that could influence information processing, decision-making, and forthcoming performance. This experiment aimed at studying how task difficulty, errors and unfair feedback may impact strain. Participants were requested to compare two polygons and to decide as quickly and accurately as possible whether these were identical or different. Task difficulty depended upon the number of polygon sides (from 12 to 21 sides) and their degree of similarity (different by 1, 2 or 3 sides). Reaction time (RT) and response accuracy were the dependent variables as well as electrodermal activity (EDA) and Instantaneous Heart Rate (IHR). Physiological variables from the autonomic nervous system were expected to evolve as a function of strain. As expected, we found that RT increased along with task difficulty. Similarly, the amplitude of IHR responses was affected by task difficulty. We recorded bradycardia during the 5s pre-stimulation period associated with correct responses, while wrong responses were associated with tachycardia. Bradycardia was thus a predictive index of performance related to the readiness to act when the participants focused on external cues. Processing identical polygons elicited longer electrodermal responses than those for different polygons. Indeed, the comparison of two different polygons ended as early as the difference was found. When similar, the participants were still looking for a difference and the issue was uncertain until the performance was displayed. Unfair information, i.e. wrong feedback associated with a good response, as well as response errors elicited larger and longer electrodermal responses. Autonomic nervous system activity was thus task-specific, and correlated to both cognitive and emotional processes. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigating cognitive ability and self-reported driving performance of post-stroke adults in a driving simulator.

PubMed

Blane, Alison; Falkmer, Torbjörn; Lee, Hoe C; Dukic Willstrand, Tania

2018-01-01

Background Safe driving is a complex activity that requires calibration. This means the driver can accurately assess the level of task demand required for task completion and can accurately evaluate their driving capability. There is much debate on the calibration ability of post-stroke drivers. Objectives The aim of this study was to assess the cognition, self-rated performance, and estimation of task demand in a driving simulator with post-stroke drivers and controls. Methods A between-groups study design was employed, which included a post-stroke driver group and a group of similarly aged older control drivers. Both groups were observed driving in two simulator-based driving scenarios and asked to complete the NASA Task Load Index (TLX) to assess their perceived task demand and self-rate their driving performance. Participants also completed a battery of psychometric tasks to assess attention and executive function, which was used to determine whether post-stroke cognitive impairment impacted on calibration. Results There was no difference in the amount of perceived task demand required to complete the driving task. Despite impairments in cognition, the post-stroke drivers were not more likely to over-estimate their driving abilities than controls. On average, the post-stroke drivers self-rated themselves more poorly than the controls and this rating was related to cognitive ability. Conclusion This study suggests that post-stroke drivers may be aware of their deficits and adjust their driving behavior. Furthermore, using self-performance measures alongside a driving simulator and cognitive assessments may provide complementary fitness-to-drive assessments, as well as rehabilitation tools during post-stroke recovery.

The impact of heat stress on operative performance and cognitive function during simulated laparoscopic operative tasks.

PubMed

Berg, Regan J; Inaba, Kenji; Sullivan, Maura; Okoye, Obi; Siboni, Stefano; Minneti, Michael; Teixeira, Pedro G; Demetriades, Demetrios

2015-01-01

Increasing ambient temperature to prevent intraoperative patient hypothermia remains widely advocated despite unconvincing evidence of efficacy. Heat stress is associated with decreased cognitive and psychomotor performance across multiple tasks but remains unexamined in an operative context. We assessed the impact of increased ambient temperature on laparoscopic operative performance and surgeon cognitive stress. Forty-two performance measures were obtained from 21 surgery trainees participating in the counter-balanced, within-subjects study protocol. Operative performance was evaluated with adaptations of the validated, peg-transfer, and intracorporeal knot-tying tasks from the Fundamentals of Laparoscopic Surgery program. Participants trained to proficiency before enrollment. Task performance was measured at two ambient temperatures, 19 and 26°C (66 and 79°F). Participants were randomly counterbalanced to initial hot or cold exposure before crossing over to the alternate environment. Cognitive stress was measured using the validated Surgical Task Load Index (SURG-TLX). No differences in performance of the peg-transfer and intracorporeal knot-tying tasks were seen across ambient conditions. Assessed via use of the six bipolar scales of the SURG-TLX, we found differences in task workload between the hot and cold conditions in the areas of physical demands (hot 10 [3-12], cold 5 [2.5-9], P = .013) and distractions (hot 8 [3.5-15.5], cold 3 [1.5-5.5], P = .001). Participant perception of distraction remained greater in the hot condition on full scoring of the SURG-TLX. Increasing ambient temperature to levels advocated for prevention of intraoperative hypothermia does not greatly decrease technical performance in short operative tasks. Surgeons, however, do report increased perceptions of distraction and physical demand. The impact of these findings on performance and outcomes during longer operative procedures remains unclear. Copyright © 2015 Elsevier Inc. All rights reserved.

Speech variability effects on recognition accuracy associated with concurrent task performance by pilots

NASA Technical Reports Server (NTRS)

Simpson, C. A.

1985-01-01

In the present study of the responses of pairs of pilots to aircraft warning classification tasks using an isolated word, speaker-dependent speech recognition system, the induced stress was manipulated by means of different scoring procedures for the classification task and by the inclusion of a competitive manual control task. Both speech patterns and recognition accuracy were analyzed, and recognition errors were recorded by type for an isolated word speaker-dependent system and by an offline technique for a connected word speaker-dependent system. While errors increased with task loading for the isolated word system, there was no such effect for task loading in the case of the connected word system.

Using event-related fMRI to examine sustained attention processes and effects of APOE ε4 in young adults.

PubMed

Evans, Simon; Clarke, Devin; Dowell, Nicholas G; Tabet, Naji; King, Sarah L; Hutton, Samuel B; Rusted, Jennifer M

2018-01-01

In this study we investigated effects of the APOE ε4 allele (which confers an enhanced risk of poorer cognitive ageing, and Alzheimer's Disease) on sustained attention (vigilance) performance in young adults using the Rapid Visual Information Processing (RVIP) task and event-related fMRI. Previous fMRI work with this task has used block designs: this study is the first to image an extended (6-minute) RVIP task. Participants were 26 carriers of the APOE ε4 allele, and 26 non carriers (aged 18-28). Pupil diameter was measured throughout, as an index of cognitive effort. We compared activity to RVIP task hits to hits on a control task (with similar visual parameters and response requirements but no working memory load): this contrast showed activity in medial frontal, inferior and superior parietal, temporal and visual cortices, consistent with previous work, demonstrating that meaningful neural data can be extracted from the RVIP task over an extended interval and using an event-related design. Behavioural performance was not affected by genotype; however, a genotype by condition (experimental task/control task) interaction on pupil diameter suggested that ε4 carriers deployed more effort to the experimental compared to the control task. fMRI results showed a condition by genotype interaction in the right hippocampal formation: only ε4 carriers showed downregulation of this region to experimental task hits versus control task hits. Experimental task beta values were correlated against hit rate: parietal correlations were seen in ε4 carriers only, frontal correlations in non-carriers only. The data indicate that, in the absence of behavioural differences, young adult ε4 carriers already show a different linkage between functional brain activity and behaviour, as well as aberrant hippocampal recruitment patterns. This may have relevance for genotype differences in cognitive ageing trajectories.

75 FR 62611 - Interagency Task Force on Veterans Small Business Development

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2010-10-12

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77 FR 41472 - Interagency Task Force on Veterans Small Business Development

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2012-07-13

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76 FR 8393 - Interagency Task Force on Veterans Small Business Development

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2011-02-14

... SMALL BUSINESS ADMINISTRATION Interagency Task Force on Veterans Small Business Development AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force meeting... public meeting of the Interagency Task Force on Veterans Small Business Development. The meeting will be...