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.

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.

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.

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.

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.

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.

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.

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.

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.

TxDOT administration research : tasks completed in FY2009.

DOT National Transportation Integrated Search

2010-01-01

Texas Department of Transportation (TxDOT) Project 0-6581-TI, TxDOT Administration : Research, encompasses multiple tasks that explore and support administrative aspects of : transportation research. : The project term began in October 2008 and has b...

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.

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.

Monitoring task loading with multivariate EEG measures during complex forms of human-computer interaction

NASA Technical Reports Server (NTRS)

Smith, M. E.; Gevins, A.; Brown, H.; Karnik, A.; Du, R.

2001-01-01

Electroencephalographic (EEG) recordings were made while 16 participants performed versions of a personal-computer-based flight simulation task of low, moderate, or high difficulty. As task difficulty increased, frontal midline theta EEG activity increased and alpha band activity decreased. A participant-specific function that combined multiple EEG features to create a single load index was derived from a sample of each participant's data and then applied to new test data from that participant. Index values were computed for every 4 s of task data. Across participants, mean task load index values increased systematically with increasing task difficulty and differed significantly between the different task versions. Actual or potential applications of this research include the use of multivariate EEG-based methods to monitor task loading during naturalistic computer-based work.

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.

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…

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

Cue Utilization and Cognitive Load in Novel Task Performance

PubMed Central

Brouwers, Sue; Wiggins, Mark W.; Helton, William; O’Hare, David; Griffin, Barbara

2016-01-01

This study was designed to examine whether differences in cue utilization were associated with differences in performance during a novel, simulated rail control task, and whether these differences reflected a reduction in cognitive load. Two experiments were conducted, the first of which involved the completion of a 20-min rail control simulation that required participants to re-route trains that periodically required a diversion. Participants with a greater level of cue utilization recorded a consistently greater response latency, consistent with a strategy that maintained accuracy, but reduced the demands on cognitive resources. In the second experiment, participants completed the rail task, during which a concurrent, secondary task was introduced. The results revealed an interaction, whereby participants with lesser levels of cue utilization recorded an increase in response latency that exceeded the response latency recorded for participants with greater levels of cue utilization. The relative consistency of response latencies for participants with greater levels of cue utilization, across all blocks, despite the imposition of a secondary task, suggested that those participants with greater levels of cue utilization had adopted a strategy that was effectively minimizing the impact of additional sources of cognitive load on their performance. PMID:27064669

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.

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.

[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.

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

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.

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.

Human Footprint Variation while Performing Load Bearing Tasks

PubMed Central

Wall-Scheffler, Cara M.; Wagnild, Janelle; Wagler, Emily

2015-01-01

Human footprint fossils have provided essential evidence about the evolution of human bipedalism as well as the social dynamics of the footprint makers, including estimates of speed, sex and group composition. Generally such estimates are made by comparing footprint evidence with modern controls; however, previous studies have not accounted for the variation in footprint dimensions coming from load bearing activities. It is likely that a portion of the hominins who created these fossil footprints were carrying a significant load, such as offspring or foraging loads, which caused variation in the footprint which could extend to variation in any estimations concerning the footprint’s maker. To identify significant variation in footprints due to load-bearing tasks, we had participants (N = 30, 15 males and 15 females) walk at a series of speeds carrying a 20kg pack on their back, side and front. Paint was applied to the bare feet of each participant to create footprints that were compared in terms of foot length, foot width and foot area. Female foot length and width increased during multiple loaded conditions. An appreciation of footprint variability associated with carrying loads adds an additional layer to our understanding of the behavior and morphology of extinct hominin populations. PMID:25738496

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.

Changes in Predictive Task Switching with Age and with Cognitive Load.

PubMed

Levy-Tzedek, Shelly

2017-01-01

Predictive control of movement is more efficient than feedback-based control, and is an important skill in everyday life. We tested whether the ability to predictively control movements of the upper arm is affected by age and by cognitive load. A total of 63 participants were tested in two experiments. In both experiments participants were seated, and controlled a cursor on a computer screen by flexing and extending their dominant arm. In Experiment 1, 20 young adults and 20 older adults were asked to continuously change the frequency of their horizontal arm movements, with the goal of inducing an abrupt switch between discrete movements (at low frequencies) and rhythmic movements (at high frequencies). We tested whether that change was performed based on a feed-forward (predictive) or on a feedback (reactive) control. In Experiment 2, 23 young adults performed the same task, while being exposed to a cognitive load half of the time via a serial subtraction task. We found that both aging and cognitive load diminished, on average, the ability of participants to predictively control their movements. Five older adults and one young adult under a cognitive load were not able to perform the switch between rhythmic and discrete movement (or vice versa). In Experiment 1, 40% of the older participants were able to predictively control their movements, compared with 70% in the young group. In Experiment 2, 48% of the participants were able to predictively control their movements with a cognitively loading task, compared with 70% in the no-load condition. The ability to predictively change a motor plan in anticipation of upcoming changes may be an important component in performing everyday functions, such as safe driving and avoiding falls.

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.

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.

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.

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 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.

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.

Prospective memory in young and older adults: the effects of task importance and ongoing task load.

PubMed

Smith, Rebekah E; Hunt, R Reed

2014-01-01

Remembering to perform an action in the future, called prospective memory, often shows age-related differences in favor of young adults when tested in the laboratory. Recently Smith, Horn, and Bayen (2012; Aging, Neuropsychology, and Cognition, 19, 495) embedded a PM task in an ongoing color-matching task and manipulated the difficulty of the ongoing task by varying the number of colors on each trial of the task. Smith et al. found that age-related differences in PM performance (lower PM performance for older adults relative to young adults) persisted even when older adults could perform the ongoing task as well or better than the young adults. The current study investigates a possible explanation for the pattern of results reported by Smith et al. by including a manipulation of task emphasis: for half of the participants the prospective memory task was emphasize, while for the other half the ongoing color-matching task was emphasized. Older adults performed a 4-color version of the ongoing color-matching task, while young adults completed either the 4-color or a more difficult 6-color version of the ongoing task. Older adults failed to perform as well as the young adults on the prospective memory task regardless of task emphasis, even when older adults were performing as well or better than the young adults on the ongoing color-matching task. The current results indicate that the lack of an effect of ongoing task load on prospective memory task performance is not due to a perception that one or the other task is more important than the other.

Low-back electromyography (EMG) data-driven load classification for dynamic lifting tasks.

PubMed

Totah, Deema; Ojeda, Lauro; Johnson, Daniel D; Gates, Deanna; Mower Provost, Emily; Barton, Kira

2018-01-01

Numerous devices have been designed to support the back during lifting tasks. To improve the utility of such devices, this research explores the use of preparatory muscle activity to classify muscle loading and initiate appropriate device activation. The goal of this study was to determine the earliest time window that enabled accurate load classification during a dynamic lifting task. Nine subjects performed thirty symmetrical lifts, split evenly across three weight conditions (no-weight, 10-lbs and 24-lbs), while low-back muscle activity data was collected. Seven descriptive statistics features were extracted from 100 ms windows of data. A multinomial logistic regression (MLR) classifier was trained and tested, employing leave-one subject out cross-validation, to classify lifted load values. Dimensionality reduction was achieved through feature cross-correlation analysis and greedy feedforward selection. The time of full load support by the subject was defined as load-onset. Regions of highest average classification accuracy started at 200 ms before until 200 ms after load-onset with average accuracies ranging from 80% (±10%) to 81% (±7%). The average recall for each class ranged from 69-92%. These inter-subject classification results indicate that preparatory muscle activity can be leveraged to identify the intent to lift a weight up to 100 ms prior to load-onset. The high accuracies shown indicate the potential to utilize intent classification for assistive device applications. Active assistive devices, e.g. exoskeletons, could prevent back injury by off-loading low-back muscles. Early intent classification allows more time for actuators to respond and integrate seamlessly with the user.

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.

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.

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.

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

Low-back electromyography (EMG) data-driven load classification for dynamic lifting tasks

PubMed Central

Ojeda, Lauro; Johnson, Daniel D.; Gates, Deanna; Mower Provost, Emily; Barton, Kira

2018-01-01

Objective Numerous devices have been designed to support the back during lifting tasks. To improve the utility of such devices, this research explores the use of preparatory muscle activity to classify muscle loading and initiate appropriate device activation. The goal of this study was to determine the earliest time window that enabled accurate load classification during a dynamic lifting task. Methods Nine subjects performed thirty symmetrical lifts, split evenly across three weight conditions (no-weight, 10-lbs and 24-lbs), while low-back muscle activity data was collected. Seven descriptive statistics features were extracted from 100 ms windows of data. A multinomial logistic regression (MLR) classifier was trained and tested, employing leave-one subject out cross-validation, to classify lifted load values. Dimensionality reduction was achieved through feature cross-correlation analysis and greedy feedforward selection. The time of full load support by the subject was defined as load-onset. Results Regions of highest average classification accuracy started at 200 ms before until 200 ms after load-onset with average accuracies ranging from 80% (±10%) to 81% (±7%). The average recall for each class ranged from 69–92%. Conclusion These inter-subject classification results indicate that preparatory muscle activity can be leveraged to identify the intent to lift a weight up to 100 ms prior to load-onset. The high accuracies shown indicate the potential to utilize intent classification for assistive device applications. Significance Active assistive devices, e.g. exoskeletons, could prevent back injury by off-loading low-back muscles. Early intent classification allows more time for actuators to respond and integrate seamlessly with the user. PMID:29447252

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…

Using the NASA Task Load Index to Assess Workload in Electronic Medical Records.

PubMed

Hudson, Darren; Kushniruk, Andre W; Borycki, Elizabeth M

2015-01-01

Electronic medical records (EMRs) has been expected to decrease health professional workload. The NASA Task Load Index has become an important tool for assessing workload in many domains. However, its application in assessing the impact of an EMR on nurse's workload has remained to be explored. In this paper we report the results of a study of workload and we explore the utility of applying the NASA Task Load Index to assess impact of an EMR at the end of its lifecycle on nurses' workload. It was found that mental and temporal demands were the most responsible for the workload. Further work along these lines is recommended.

Immune networks: multi-tasking capabilities at medium load

NASA Astrophysics Data System (ADS)

Agliari, E.; Annibale, A.; Barra, A.; Coolen, A. C. C.; Tantari, D.

2013-08-01

Associative network models featuring multi-tasking properties have been introduced recently and studied in the low-load regime, where the number P of simultaneously retrievable patterns scales with the number N of nodes as P ˜ log N. In addition to their relevance in artificial intelligence, these models are increasingly important in immunology, where stored patterns represent strategies to fight pathogens and nodes represent lymphocyte clones. They allow us to understand the crucial ability of the immune system to respond simultaneously to multiple distinct antigen invasions. Here we develop further the statistical mechanical analysis of such systems, by studying the medium-load regime, P ˜ Nδ with δ ∈ (0, 1]. We derive three main results. First, we reveal the nontrivial architecture of these networks: they exhibit a high degree of modularity and clustering, which is linked to their retrieval abilities. Second, by solving the model we demonstrate for δ < 1 the existence of large regions in the phase diagram where the network can retrieve all stored patterns simultaneously. Finally, in the high-load regime δ = 1 we find that the system behaves as a spin-glass, suggesting that finite-connectivity frameworks are required to achieve effective retrieval.

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.

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.

Analysis of tasks for dynamic man/machine load balancing in advanced helicopters

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

Jorgensen, C.C.

1987-10-01

This report considers task allocation requirements imposed by advanced helicopter designs incorporating mixes of human pilots and intelligent machines. Specifically, it develops an analogy between load balancing using distributed non-homogeneous multiprocessors and human team functions. A taxonomy is presented which can be used to identify task combinations likely to cause overload for dynamic scheduling and process allocation mechanisms. Designer criteria are given for function decomposition, separation of control from data, and communication handling for dynamic tasks. Possible effects of n-p complete scheduling problems are noted and a class of combinatorial optimization methods are examined.

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

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.

Postcategorical auditory distraction in short-term memory: Insights from increased task load and task type.

PubMed

Marsh, John E; Yang, Jingqi; Qualter, Pamela; Richardson, Cassandra; Perham, Nick; Vachon, François; Hughes, Robert W

2018-06-01

Task-irrelevant speech impairs short-term serial recall appreciably. On the interference-by-process account, the processing of physical (i.e., precategorical) changes in speech yields order cues that conflict with the serial-ordering process deployed to perform the serial recall task. In this view, the postcategorical properties (e.g., phonology, meaning) of speech play no role. The present study reassessed the implications of recent demonstrations of auditory postcategorical distraction in serial recall that have been taken as support for an alternative, attentional-diversion, account of the irrelevant speech effect. Focusing on the disruptive effect of emotionally valent compared with neutral words on serial recall, we show that the distracter-valence effect is eliminated under conditions-high task-encoding load-thought to shield against attentional diversion whereas the general effect of speech (neutral words compared with quiet) remains unaffected (Experiment 1). Furthermore, the distracter-valence effect generalizes to a task that does not require the processing of serial order-the missing-item task-whereas the effect of speech per se is attenuated in this task (Experiment 2). We conclude that postcategorical auditory distraction phenomena in serial short-term memory (STM) are incidental: they are observable in such a setting but, unlike the acoustically driven irrelevant speech effect, are not integral to it. As such, the findings support a duplex-mechanism account over a unitary view of auditory distraction. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

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…

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.

Validation of auditory detection response task method for assessing the attentional effects of cognitive load.

PubMed

Stojmenova, Kristina; Sodnik, Jaka

2018-07-04

There are 3 standardized versions of the Detection Response Task (DRT), 2 using visual stimuli (remote DRT and head-mounted DRT) and one using tactile stimuli. In this article, we present a study that proposes and validates a type of auditory signal to be used as DRT stimulus and evaluate the proposed auditory version of this method by comparing it with the standardized visual and tactile version. This was a within-subject design study performed in a driving simulator with 24 participants. Each participant performed 8 2-min-long driving sessions in which they had to perform 3 different tasks: driving, answering to DRT stimuli, and performing a cognitive task (n-back task). Presence of additional cognitive load and type of DRT stimuli were defined as independent variables. DRT response times and hit rates, n-back task performance, and pupil size were observed as dependent variables. Significant changes in pupil size for trials with a cognitive task compared to trials without showed that cognitive load was induced properly. Each DRT version showed a significant increase in response times and a decrease in hit rates for trials with a secondary cognitive task compared to trials without. Similar and significantly better results in differences in response times and hit rates were obtained for the auditory and tactile version compared to the visual version. There were no significant differences in performance rate between the trials without DRT stimuli compared to trials with and among the trials with different DRT stimuli modalities. The results from this study show that the auditory DRT version, using the signal implementation suggested in this article, is sensitive to the effects of cognitive load on driver's attention and is significantly better than the remote visual and tactile version for auditory-vocal cognitive (n-back) secondary tasks.

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.

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.

Improving Sensitivity to Detect Mild Cognitive Impairment: Cognitive Load Dual-Task Gait Speed Assessment.

PubMed

MacAulay, Rebecca K; Wagner, Mark T; Szeles, Dana; Milano, Nicholas J

2017-07-01

Longitudinal research indicates that cognitive load dual-task gait assessment is predictive of cognitive decline and thus might provide a sensitive measure to screen for mild cognitive impairment (MCI). However, research among older adults being clinically evaluated for cognitive concerns, a defining feature of MCI, is lacking. The present study investigated the effect of performing a cognitive task on normal walking speed in patients presenting to a memory clinic with cognitive complaints. Sixty-one patients with a mean age of 68 years underwent comprehensive neuropsychological testing, clinical interview, and gait speed (simple- and dual-task conditions) assessments. Thirty-four of the 61 patients met criteria for MCI. Repeated measure analyses of covariance revealed that greater age and MCI both significantly associated with slower gait speed, ps<.05. Follow-up analysis indicated that the MCI group had significantly slower dual-task gait speed but did not differ in simple-gait speed. Multivariate linear regression across groups found that executive attention performance accounted for 27.4% of the variance in dual-task gait speed beyond relevant demographic and health risk factors. The present study increases the external validity of dual-task gait assessment of MCI. Differences in dual-task gait speed appears to be largely attributable to executive attention processes. These findings have clinical implications as they demonstrate expected patterns of gait-brain behavior relationships in response to a cognitive dual task within a clinically representative population. Cognitive load dual-task gait assessment may provide a cost efficient and sensitive measure to detect older adults at high risk of a dementia disorder. (JINS, 2017, 23, 493-501).

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.

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.

Vegetable Oil-Loaded Nanocapsules: Innovative Alternative for Incorporating Drugs for Parenteral Administration.

PubMed

Venturinil, C G; Bruinsmann, A; Oliveira, C P; Contri, R V; Pohlmann, A R; Guterres, S S

2016-02-01

An innovative nanocapsule formulation for parenteral administration using selected vegetable oils (mango, jojoba, pequi, oat, annatto, calendula, and chamomile) was developed that has the potential to encapsulate various drugs. The vegetable oil-loaded nanocapsules were prepared by interfacial deposition and compared with capric/caprylic triglyceride-loaded lipid core nanocapsules. The major objective was to investigate the effect of vegetable oils on particle size distribution and physical stability and to determine the hemolytic potential of the nanocapsules, considering their applicability for intravenous administration. Taking into account the importance of accurately determining particle size for the selected route of administration, different size characterization techniques were employed, such as Laser Diffraction, Dynamic Light Scattering, Multiple Light Scattering, Nanoparticle Tracking Analysis, and Transmission Electronic Microscopy. Laser diffraction studies indicated that the mean particle size of all nanocapsules was below 300 nm. For smaller particles, the laser diffraction and multiple light scattering data were in agreement (D[3,2]-130 nm). Dynamic light scattering and nanoparticle tracking analysis, two powerful techniques that complement each other, exhibited size values between 180 and 259 nm for all nanoparticles. Stability studies demonstrated a tendency of particle creaming for jojoba-nanocapsules and sedimentation for the other nanoparticles; however, no size variation occurred over 30 days. The hemolysis test proved the hemocompatibility of all nanosystems, irrespective of the type of oil. Although all developed nanocapsules presented the potential for parenteral administration, jojoba oil-loaded nanocapsules were selected as the most promising nanoformulation due to their low average size and high particle size homogeneity.

Fuzzy-TLX: using fuzzy integrals for evaluating human mental workload with NASA-Task Load indeX in laboratory and field studies.

PubMed

Mouzé-Amady, Marc; Raufaste, Eric; Prade, Henri; Meyer, Jean-Pierre

2013-01-01

The aim of this study was to assess mental workload in which various load sources must be integrated to derive reliable workload estimates. We report a new algorithm for computing weights from qualitative fuzzy integrals and apply it to the National Aeronautics and Space Administration -Task Load indeX (NASA-TLX) subscales in order to replace the standard pair-wise weighting technique (PWT). In this paper, two empirical studies were reported: (1) In a laboratory experiment, age- and task-related variables were investigated in 53 male volunteers and (2) In a field study, task- and job-related variables were studied on aircrews during 48 commercial flights. The results found in this study were as follows: (i) in the experimental setting, fuzzy estimates were highly correlated with classical (using PWT) estimates; (ii) in real work conditions, replacing PWT by automated fuzzy treatments simplified the NASA-TLX completion; (iii) the algorithm for computing fuzzy estimates provides a new classification procedure sensitive to various variables of work environments and (iv) subjective and objective measures can be used for the fuzzy aggregation of NASA-TLX subscales. NASA-TLX, a classical tool for mental workload assessment, is based on a weighted sum of ratings from six subscales. A new algorithm, which impacts on input data collection and computes weights and indexes from qualitative fuzzy integrals, is evaluated through laboratory and field studies. Pros and cons are discussed.

Shoulder joint loading and posture during medicine cart pushing task.

PubMed

Xu, Xu; Lin, Jia-Hua; Boyer, Jon

2013-01-01

Excessive physical loads and awkward shoulder postures during pushing and pulling are risk factors for shoulder pain. Pushing a medicine cart is a major component of a work shift for nurses and medical assistants in hospitals and other health care facilities. A laboratory experiment was conducted to examine the effects of common factors (e.g., lane congestion, cart load stability, floor surface friction) on shoulder joint moment and shoulder elevation angle of participants during cart pushing. Participants pushed a medicine cart on straight tracks and turning around right-angle corners. Peak shoulder joint moments reached 25.1 Nm, 20.3 Nm, and 26.8 Nm for initial, transition, and turning phases of the pushing tasks, indicating that shoulder joint loading while pushing a medical cart is comparable to levels previously reported from heavy manual activities encountered in industry (e.g., garbage collection). Also, except for user experience, all other main study factors, including congestion level, cart load stability, location of transition strip, shoulder tendency, surface friction, and handedness, significantly influenced shoulder joint moment and shoulder elevation angle. The findings provide a better understanding of shoulder exposures associated with medicine cart operations and may be helpful in designing and optimizing the physical environment where medicine carts are used.

Visual short-term memory load modulates the early attention and perception of task-irrelevant emotional faces

PubMed Central

Yang, Ping; Wang, Min; Jin, Zhenlan; Li, Ling

2015-01-01

The ability to focus on task-relevant information, while suppressing distraction, is critical for human cognition and behavior. Using a delayed-match-to-sample (DMS) task, we investigated the effects of emotional face distractors (positive, negative, and neutral faces) on early and late phases of visual short-term memory (VSTM) maintenance intervals, using low and high VSTM loads. Behavioral results showed decreased accuracy and delayed reaction times (RTs) for high vs. low VSTM load. Event-related potentials (ERPs) showed enhanced frontal N1 and occipital P1 amplitudes for negative faces vs. neutral or positive faces, implying rapid attentional alerting effects and early perceptual processing of negative distractors. However, high VSTM load appeared to inhibit face processing in general, showing decreased N1 amplitudes and delayed P1 latencies. An inverse correlation between the N1 activation difference (high-load minus low-load) and RT costs (high-load minus low-load) was found at left frontal areas when viewing negative distractors, suggesting that the greater the inhibition the lower the RT cost for negative faces. Emotional interference effect was not found in the late VSTM-related parietal P300, frontal positive slow wave (PSW) and occipital negative slow wave (NSW) components. In general, our findings suggest that the VSTM load modulates the early attention and perception of emotional distractors. PMID:26388763

Analysis of postural load during tasks related to milking cows-a case study.

PubMed

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

2011-01-01

The aim of this study was to analyse postural load during tasks related to milking cows of 2 farmers on 2 different farms (one with a manual milk transport system, the other with a fully automated milk transport system) as a case study. The participants were full-time farmers, they were both healthy and experienced in their job. The Ovako Working Posture Analyzing System (OWAS) was used to evaluate postural load and postural risk. Postural load was medium for the farmer on the farm with a manual milk transport system and high for the farmer working on the farm with a fully automated milk transport system. Thus, it can be concluded that a higher level of farm mechanization not always mean that the farmer's postural load is lower, but limitation of OWAS should be considered.

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

Occupational Physical Loading Tasks and Knee Osteoarthritis: A Review of the Evidence

PubMed Central

Ezzat, Allison M.

2014-01-01

ABSTRACT Purpose: To perform a systematic review with best evidence synthesis examining the literature on the relationship between occupational loading tasks and knee osteoarthritis (OA). Methods: Two databases were searched to identify articles published between 1946 and April, 2011. Eligible studies were those that (1) included adults reporting on their employment history; (2) measured individuals' exposure to work-related activities with heavy loading in the knee joint; and (3) identified presence of knee OA (determined by X-ray), cartilage defects associated with knee OA (identified by magnetic resonance imaging), or joint replacement surgery. Results: A total of 32 articles from 31 studies met the inclusion criteria. We found moderate evidence that combined heavy lifting and kneeling is a risk factor for knee OA, with odds ratios (OR) varying from 1.8 to 7.9, and limited evidence for heavy lifting (OR=1.4–7.3), kneeling (OR=1.5–6.9), stair climbing (OR=1.6–5.1), and occupational groups (OR=1.4–4.7) as risk factors. When examined by sex, moderate level evidence of knee OA was found in men; however, the evidence in women was limited. Conclusions: Further high-quality prospective studies are warranted to provide further evidence on the role of occupational loading tasks in knee OA, particularly in women. PMID:24719516

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

Administrative Task Force on the Four Day Work Week. Final Report.

ERIC Educational Resources Information Center

California State Univ., Los Angeles.

The Administrative Task Force on a 4-day work week at California State University in Los Angeles was charged with the following responsibilities: (1) To make an indepth study of the "literature" of experience of other universities, a survey of staff, faculty, and students if required, and other activities that will result in setting up a…

[Administrative and reporting tasks of family physicians in Europe. Comparison with the Hungarian system].

PubMed

Rurik, Imre; Kalabay, László

2008-05-11

Administrative tasks are continuously increasing in the different health systems worldwide and also in the primary care. The administrative and reporting tasks of family physicians in Hungary are regulated by laws and rules. The aim of the study was to compare the recent Hungarian administrative tasks to those of other European countries in the primary care. Family physicians from 22 countries of the European General Practice Research Network were asked to fill a questionnaire regarding their countries. The results of their answers were presented and analyzed. Doctors are paid by capitation or fee for services, sometimes by the combination of both. They are obliged to prepare reports which depend on the respective countries, contain identification data of patients, diagnoses to be set up, and treatments. Administrative duties and the national characteristics of drug-prescriptions, referral systems to specialist or hospital were also analyzed. Conclusions were made in comparison with the European and Hungarian regulations. Reports needed by the Hungarian authorities are more complex and detailed, with many overlaps. The reasons why data are needed are often not clear and do not fit for the purpose. The time available for medical treatment is decreased by administrative duties making the gate-keeper function ineffective. There is no time for real prevention. Without official (governmental) version of primary care softwares, family physicians use too many softwares with different quality, which are not compatible with each other. It is suggested to check and modify the data obliged in reporting systems. Only data relevant in epidemiological or economical points of view should be reported with more focus to personal protection of privacy rights.

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…

Effect of task load and task load increment on performance and workload

NASA Technical Reports Server (NTRS)

Hancock, P. A.; Williams, G.

1993-01-01

The goal of adaptive automated task allocation is the 'seamless' transfer of work demand between human and machine. Clearly, at the present time, we are far from this objective. One of the barriers to achieving effortless human-machine symbiosis is an inadequate understanding of the way in which operators themselves seek to reallocate demand among their own personal 'resources.' The paper addresses this through an examination of workload response, which scales an individual's reaction to common levels of experienced external demand. The results indicate the primary driver of performance is the absolute level of task demand over the increment in that demand.

78 FR 9928 - Food and Drug Administration Drug Shortages Task Force and Strategic Plan; Request for Comments

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-12

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2013-N-0124] Food and Drug Administration Drug Shortages Task Force and Strategic Plan; Request for Comments AGENCY: Food and Drug Administration, HHS. ACTION: Notice; request for comments. SUMMARY: To assist the Food...

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.

Individual differences in working memory capacity determine the effects of oculomotor task load on concurrent word recall performance.

PubMed

Lee, Eun-Ju; Kwon, Gusang; Lee, Aekyoung; Ghajar, Jamshid; Suh, Minah

2011-07-05

In this study, the interaction between individual differences in working memory capacity, which were assessed by the Korean version of the California Verbal Learning Test (K-CVLT), and the effects of oculomotor task load on word recall performance are examined in a dual-task experiment. We hypothesized that varying levels of oculomotor task load should result in different demands on cognitive resources. The verbal working memory task used in this study involved a brief exposure to seven words to be remembered, followed by a 30-second delay during which the subject carried out an oculomotor task. Then, memory performance was assessed by having the subjects recall as many words as possible. Forty healthy normal subjects with no vision-related problems carried out four separate dual-tasks over four consecutive days of participation, wherein word recall performances were tested under unpredictable random SPEM (smooth pursuit eye movement), predictive SPEM, fixation, and eyes-closed conditions. The word recall performance of subjects with low K-CVLT scores was significantly enhanced under predictive SPEM conditions as opposed to the fixation and eyes-closed conditions, but performance was reduced under the random SPEM condition, thus reflecting an inverted-U relationship between the oculomotor task load and word recall performance. Subjects with high K-CVLT scores evidenced steady word recall performances, regardless of the type of oculomotor task performed. The concurrent oculomotor performance measured by velocity error did not differ significantly among the K-CVLT groups. However, the high-scoring subjects evidenced smaller phase errors under predictive SPEM conditions than did the low-scoring subjects; this suggests that different resource allocation strategies may be adopted, depending on individuals' working memory capacity. Copyright © 2011 Elsevier B.V. All rights reserved.

The Relationship between Task-Induced Involvement Load and Learning New Words from Context

ERIC Educational Resources Information Center

Nassaji, Hossein; Hu, Hsueh-chao Marcella

2012-01-01

This study investigated the relationship between task-induced involvement load and ESL learners' inferencing and learning word meanings from context. Thirty-two ESL learners were randomly assigned to one of three groups, with each group receiving a different version of a text that was assumed to differ from one another in terms of the degree of…

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.

Disadvantageous Deck Selection in the Iowa Gambling Task: The Effect of Cognitive Load

PubMed Central

Hawthorne, Melissa J.; Pierce, Benton H.

2015-01-01

Research has shown that cognitive load affects overall Iowa Gambling Task (IGT) performance, but it is unknown whether such load impacts the selection of the individual decks that correspond to gains or losses. Here, participants performed the IGT either in a full attention condition or while engaged in a number monitoring task to divide attention. Results showed that the full attention group was more aware of the magnitude of gains or losses for each draw (i.e., payoff awareness) than was the divided attention group. However, the divided attention group was more sensitive to the frequency of the losses (i.e., frequency awareness), as evidenced by their increased preference for Deck B, which is the large but infrequent loss deck. An analysis across blocks showed that the number monitoring group was consistently more aware of loss frequency, whereas the full attention group shifted between awareness of loss frequency and awareness of payoff amount. Furthermore, the full attention group was better able to weigh loss frequency and payoff amount when making deck selections. These findings support the notion that diminished cognitive resources may result in greater selection of Deck B, otherwise known as the prominent Deck B phenomenon. PMID:27247661

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.

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

Sustained attention failures are primarily due to sustained cognitive load not task monotony.

PubMed

Head, James; Helton, William S

2014-11-01

We conducted two studies using a modified sustained attention to response task (SART) to investigate the developmental process of SART performance and the role of cognitive load on performance when the speed-accuracy trade-off is controlled experimentally. In study 1, 23 participants completed the modified SART (target stimuli location was not predictable) and a subjective thought content questionnaire 4 times over the span of 4 weeks. As predicted, the influence of speed-accuracy trade-off was significantly mitigated on the modified SART by having target stimuli occur in unpredictable locations. In study 2, 21 of the 23 participants completed an abridged version of the modified SART with a verbal free-recall memory task. Participants performed significantly worse when completing the verbal memory task and SART concurrently. Overall, the results support a resource theory perspective with concern to errors being a result of limited mental resources and not simply mindlessness per se. Copyright © 2014. Published by Elsevier B.V.

Evidence-Based Clinical Recommendations for the Administration of the Sequential Motion Rates Task

ERIC Educational Resources Information Center

Icht, Michal; Ben-David, Boaz M.

2018-01-01

The sequential motion rates (SMR) task, that involves rapid and accurate repetitions of a syllable sequence, /pataka/, is a commonly used evaluation tool for oro-motor abilities. Although the SMR is a well-known tool, some aspects of its administration protocol are unspecified. We address the following factors and their role in the SMR protocol:…

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.

Regression models for predicting peak and continuous three-dimensional spinal loads during symmetric and asymmetric lifting tasks.

PubMed

Fathallah, F A; Marras, W S; Parnianpour, M

1999-09-01

Most biomechanical assessments of spinal loading during industrial work have focused on estimating peak spinal compressive forces under static and sagittally symmetric conditions. The main objective of this study was to explore the potential of feasibly predicting three-dimensional (3D) spinal loading in industry from various combinations of trunk kinematics, kinetics, and subject-load characteristics. The study used spinal loading, predicted by a validated electromyography-assisted model, from 11 male participants who performed a series of symmetric and asymmetric lifts. Three classes of models were developed: (a) models using workplace, subject, and trunk motion parameters as independent variables (kinematic models); (b) models using workplace, subject, and measured moments variables (kinetic models); and (c) models incorporating workplace, subject, trunk motion, and measured moments variables (combined models). The results showed that peak 3D spinal loading during symmetric and asymmetric lifting were predicted equally well using all three types of regression models. Continuous 3D loading was predicted best using the combined models. When the use of such models is infeasible, the kinematic models can provide adequate predictions. Finally, lateral shear forces (peak and continuous) were consistently underestimated using all three types of models. The study demonstrated the feasibility of predicting 3D loads on the spine under specific symmetric and asymmetric lifting tasks without the need for collecting EMG information. However, further validation and development of the models should be conducted to assess and extend their applicability to lifting conditions other than those presented in this study. Actual or potential applications of this research include exposure assessment in epidemiological studies, ergonomic intervention, and laboratory task assessment.

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.

Socio-cognitive load and social anxiety in an emotional anti-saccade task

PubMed Central

Butler, Stephen H.; Grealy, Madeleine A.

2018-01-01

The anti-saccade task has been used to measure attentional control related to general anxiety but less so with social anxiety specifically. Previous research has not been conclusive in suggesting that social anxiety may lead to difficulties in inhibiting faces. It is possible that static face paradigms do not convey a sufficient social threat to elicit an inhibitory response in socially anxious individuals. The aim of the current study was twofold. We investigated the effect of social anxiety on performance in an anti-saccade task with neutral or emotional faces preceded either by a social stressor (Experiment 1), or valenced sentence primes designed to increase the social salience of the task (Experiment 2). Our results indicated that latencies were significantly longer for happy than angry faces. Additionally, and surprisingly, high anxious participants made more erroneous anti-saccades to neutral than angry and happy faces, whilst the low anxious groups exhibited a trend in the opposite direction. Results are consistent with a general approach-avoidance response for positive and threatening social information. However increased socio-cognitive load may alter attentional control with high anxious individuals avoiding emotional faces, but finding it more difficult to inhibit ambiguous faces. The effects of social sentence primes on attention appear to be subtle but suggest that the anti-saccade task will only elicit socially relevant responses where the paradigm is more ecologically valid. PMID:29795619

Anticipatory Postural Adjustments in a Bimanual Load-Lifting Task in Children with Developmental Coordination Disorder

ERIC Educational Resources Information Center

Jover, Marianne; Schmitz, Christina; Centelles, Laurie; Chabrol, Brigitte; Assaiante, Christine

2010-01-01

Aim: Postural control is a fundamental component of action in which deficits have been shown to contribute to motor difficulties in children with developmental coordination disorder (DCD). The purpose of this study was to examine anticipatory postural adjustments (APAs) in children with DCD in a bimanual load-lifting task. Method: Sixteen children…

New Congressional Climate Change Task Force Calls on President to Use Administrative Authority

NASA Astrophysics Data System (ADS)

Showstack, Randy

2013-02-01

Spurred by U.S. congressional inaction on climate change and by President Barack Obama's comments on the topic in his 21 January inaugural address, several Democratic members of Congress announced at a Capitol Hill briefing the formation of a bicameral task force on climate change. In addition, they have called on the president to use his administrative authority to deal with the issue.

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.

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.

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

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

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.

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.

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.

Identifying interactive effects of task demands in lifting on estimates of in vivo low back joint loads.

PubMed

Gooyers, Chad E; Beach, Tyson A C; Frost, David M; Howarth, Samuel J; Callaghan, Jack P

2018-02-01

This investigation examined interactions between the magnitude of external load, movement speed and (a)symmetry of load placement on estimates of in vivo joint loading in the lumbar spine during simulated occupational lifting. Thirty-two participants with manual materials handling experience were included in the study. Three-dimensional motion data, ground reaction forces, and activation of six bilateral trunk muscle groups were captured while participants performed lifts with two loads at two movement speeds and using two load locations. L4-L5 joint compression and shear force-time histories were estimated using an EMG-assisted musculoskeletal model of the lumbar spine. Results from this investigation provide strong evidence that known mechanical low back injury risk factors should not be viewed in isolation. Rather, injury prevention efforts need to consider the complex interactions that exist between external task demands and their combined influence on internal joint loading. Copyright © 2017 Elsevier Ltd. All rights reserved.

Foot kinematics and loading of professional athletes in American football-specific tasks.

PubMed

Riley, Patrick O; Kent, Richard W; Dierks, Tracy A; Lievers, W Brent; Frimenko, Rebecca E; Crandall, Jeff R

2013-09-01

The purpose of this study was to describe stance foot and ankle kinematics and the associated ground reaction forces at the upper end of human performance in professional football players during commonly performed football-specific tasks. Nine participants were recruited from the spring training squad of a professional football team. In a motion analysis laboratory setting, participants performed three activities used at the NFL Scouting Combine to assess player speed and agility: the 3-cone drill, the shuttle run, and the standing high jump. The talocrural and first metatarsophalangial joint dorsiflexion, subtalar joint inversion, and the ground reaction forces were determined for the load bearing portions of each activity. We documented load-bearing foot and ankle kinematics of elite football players performing competition-simulating activities, and confirmed our hypothesis that the talocrural, subtalar, and metatarsophalangeal joint ranges of motion for the activities studied approached or exceeded reported physiological limits. Copyright © 2012 Elsevier B.V. All rights reserved.

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

Estimation of lumbar spinal loading and trunk muscle forces during asymmetric lifting tasks: application of whole-body musculoskeletal modelling in OpenSim.

PubMed

Kim, Hyun-Kyung; Zhang, Yanxin

2017-04-01

Large spinal compressive force combined with axial torsional shear force during asymmetric lifting tasks is highly associated with lower back injury (LBI). The aim of this study was to estimate lumbar spinal loading and muscle forces during symmetric lifting (SL) and asymmetric lifting (AL) tasks using a whole-body musculoskeletal modelling approach. Thirteen healthy males lifted loads of 7 and 12 kg under two lifting conditions (SL and AL). Kinematic data and ground reaction force data were collected and then processed by a whole-body musculoskeletal model. The results show AL produced a significantly higher peak lateral shear force as well as greater peak force of psoas major, quadratus lumborum, multifidus, iliocostalis lumborum pars lumborum, longissimus thoracis pars lumborum and external oblique than SL. The greater lateral shear forces combined with higher muscle force and asymmetrical muscle contractions may have the biomechanical mechanism responsible for the increased risk of LBI during AL. Practitioner Summary: Estimating lumbar spinal loading and muscle forces during free-dynamic asymmetric lifting tasks with a whole-body musculoskeletal modelling in OpenSim is the core value of this research. The results show that certain muscle groups are fundamentally responsible for asymmetric movement, thereby producing high lumbar spinal loading and muscle forces, which may increase risks of LBI during asymmetric lifting tasks.

The Effects of Direction of Exertion, Path, and Load Placement in Nursing Cart Pushing and Pulling Tasks: An Electromyographical Study.

PubMed

Kao, Huei Chu; Lin, Chiuhsiang Joe; Lee, Yung Hui; Chen, Su Huang

2015-01-01

The purpose of this study was to explore the effects of direction of exertion (DOE) (pushing, pulling), path (walking in a straight line, turning left, walking uphill), and load placement (LP) (the 18 blocks were indicated by X, Y and Z axis; there were 3 levels on the X axis, 2 levels on the Y axis, and 3 levels on the Z axis) on muscle activity and ratings of perceived exertion in nursing cart pushing and pulling tasks. Ten participants who were female students and not experienced nurses were recruited to participate in the experiment. Each participant performed 108 experimental trials in the study, consisting of 2 directions of exertion (push and pull), 3 paths, and 18 load placements (indicated by X, Y and Z axes). A 23kg load was placed into one load placement. The dependent variables were electromyographic (EMG) data of four muscles collected bilaterally as follows: Left (L) and right (R) trapezius (TR), flexor digitorum superficialis (FDS), extensor digitorum (ED), and erector spinae (ES) and subjective ratings of perceived exertion (RPE). Split-split-plot ANOVA was conducted to analyze significant differences between DOE, path, and LP in the EMG and RPE data. Pulling cart tasks produced a significantly higher activation of the muscles (RTR:54.4%, LTR:50.3%, LFDS:57.0%, LED:63.4%, RES:40.7%, LES:36.7%) than pushing cart tasks (RTR:42.4%, LTR:35.1%, LFDS:32.3%, LED:55.1%, RES:33.3%, LES:32.1%). A significantly greater perceived exertion was found in pulling cart tasks than pushing cart tasks. Significantly higher activation of all muscles and perceived exertion were observed for walking uphill than walking in a straight line and turning left. Significantly lower muscle activity of all muscles and subject ratings were observed for the central position on the X axis, the bottom position on the Y axis, and the posterior position on the Z axis. These findings suggest that nursing staff should adopt forward pushing when moving a nursing cart, instead of backward

The Effects of Direction of Exertion, Path, and Load Placement in Nursing Cart Pushing and Pulling Tasks: An Electromyographical Study

PubMed Central

Kao, Huei Chu; Lin, Chiuhsiang Joe; Lee, Yung Hui; Chen, Su Huang

2015-01-01

The purpose of this study was to explore the effects of direction of exertion (DOE) (pushing, pulling), path (walking in a straight line, turning left, walking uphill), and load placement (LP) (the 18 blocks were indicated by X, Y and Z axis; there were 3 levels on the X axis, 2 levels on the Y axis, and 3 levels on the Z axis) on muscle activity and ratings of perceived exertion in nursing cart pushing and pulling tasks. Ten participants who were female students and not experienced nurses were recruited to participate in the experiment. Each participant performed 108 experimental trials in the study, consisting of 2 directions of exertion (push and pull), 3 paths, and 18 load placements (indicated by X, Y and Z axes). A 23kg load was placed into one load placement. The dependent variables were electromyographic (EMG) data of four muscles collected bilaterally as follows: Left (L) and right (R) trapezius (TR), flexor digitorum superficialis (FDS), extensor digitorum (ED), and erector spinae (ES) and subjective ratings of perceived exertion (RPE). Split-split-plot ANOVA was conducted to analyze significant differences between DOE, path, and LP in the EMG and RPE data. Pulling cart tasks produced a significantly higher activation of the muscles (RTR:54.4%, LTR:50.3%, LFDS:57.0%, LED:63.4%, RES:40.7%, LES:36.7%) than pushing cart tasks (RTR:42.4%, LTR:35.1%, LFDS:32.3%, LED:55.1%, RES:33.3%, LES:32.1%). A significantly greater perceived exertion was found in pulling cart tasks than pushing cart tasks. Significantly higher activation of all muscles and perceived exertion were observed for walking uphill than walking in a straight line and turning left. Significantly lower muscle activity of all muscles and subject ratings were observed for the central position on the X axis, the bottom position on the Y axis, and the posterior position on the Z axis. These findings suggest that nursing staff should adopt forward pushing when moving a nursing cart, instead of backward

Measuring cognitive load during simulation-based psychomotor skills training: sensitivity of secondary-task performance and subjective ratings.

PubMed

Haji, Faizal A; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

2015-12-01

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 (signal detection rate, SDR and recognition reaction time, RRT) as measures of CL. In phase 1 of the study, novice learners and expert surgeons attempted a visual-monitoring task under two conditions: single-task (monitoring a virtual patient's heart-rate) and dual-task (tying surgical knots on a bench-top simulator while monitoring the virtual patient's heart-rate). Novices demonstrated higher mental effort and inferior secondary-task performance on the dual-task compared to experts (RRT 1.76 vs. 0.73, p = 0.012; SDR 0.27 vs. 0.97, p < 0.001; SRME 7.75 vs. 2.80, p < 0.001). Similarly, secondary task performance deteriorated from baseline to dual-task among novices (RRT 0.63 vs. 1.76 s, p < 0.006 and SDR 1.00 vs. 0.27, p < 0.001), but not experts (RRT 0.63 vs. 0.73 s, p = 0.124 and SDR 1.00 vs. 0.97, p = 0.178). In phase 2, novices practiced surgical knot-tying on the bench top simulator during consecutive dual-task trials. A significant increase in SDR (F(9,63) = 6.63, p < 0.001, f = 0.97) and decrease in SRME (F(9,63) = 9.39, p < 0.001, f = 1.04) was observed during simulation training, while RRT did not change significantly (F(9,63) = 1.18, p < 0.32, f = 0.41). The results suggest subjective ratings and dual-task performance can be used to track changes in CL among novices, particularly in early phases of simulation-based skills training. The implications for measuring CL in simulation instructional design research are discussed.

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

Electroencephalography Based Analysis of Working Memory Load and Affective Valence in an N-back Task with Emotional Stimuli

PubMed Central

Grissmann, Sebastian; Faller, Josef; Scharinger, Christian; Spüler, Martin; Gerjets, Peter

2017-01-01

Most brain-based measures of the electroencephalogram (EEG) are used in highly controlled lab environments and only focus on narrow mental states (e.g., working memory load). However, we assume that outside the lab complex multidimensional mental states are evoked. This could potentially create interference between EEG signatures used for identification of specific mental states. In this study, we aimed to investigate more realistic conditions and therefore induced a combination of working memory load and affective valence to reveal potential interferences in EEG measures. To induce changes in working memory load and affective valence, we used a paradigm which combines an N-back task (for working memory load manipulation) with a standard method to induce affect (affective pictures taken from the International Affective Picture System (IAPS) database). Subjective ratings showed that the experimental task was successful in inducing working memory load as well as affective valence. Additionally, performance measures were analyzed and it was found that behavioral performance decreased with increasing workload as well as negative valence, showing that affective valence can have an effect on cognitive processing. These findings are supported by changes in frontal theta and parietal alpha power, parameters used for measuring of working memory load in the EEG. However, these EEG measures are influenced by the negative valence condition as well and thereby show that detection of working memory load is sensitive to affective contexts. Unexpectedly, we did not find any effects for EEG measures typically used for affective valence detection (Frontal Alpha Asymmetry (FAA)). Therefore we assume that the FAA measure might not be usable if cognitive workload is induced simultaneously. We conclude that future studies should account for potential context-specifity of EEG measures. PMID:29311875

Electroencephalography Based Analysis of Working Memory Load and Affective Valence in an N-back Task with Emotional Stimuli.

PubMed

Grissmann, Sebastian; Faller, Josef; Scharinger, Christian; Spüler, Martin; Gerjets, Peter

2017-01-01

Most brain-based measures of the electroencephalogram (EEG) are used in highly controlled lab environments and only focus on narrow mental states (e.g., working memory load). However, we assume that outside the lab complex multidimensional mental states are evoked. This could potentially create interference between EEG signatures used for identification of specific mental states. In this study, we aimed to investigate more realistic conditions and therefore induced a combination of working memory load and affective valence to reveal potential interferences in EEG measures. To induce changes in working memory load and affective valence, we used a paradigm which combines an N-back task (for working memory load manipulation) with a standard method to induce affect (affective pictures taken from the International Affective Picture System (IAPS) database). Subjective ratings showed that the experimental task was successful in inducing working memory load as well as affective valence. Additionally, performance measures were analyzed and it was found that behavioral performance decreased with increasing workload as well as negative valence, showing that affective valence can have an effect on cognitive processing. These findings are supported by changes in frontal theta and parietal alpha power, parameters used for measuring of working memory load in the EEG. However, these EEG measures are influenced by the negative valence condition as well and thereby show that detection of working memory load is sensitive to affective contexts. Unexpectedly, we did not find any effects for EEG measures typically used for affective valence detection (Frontal Alpha Asymmetry (FAA)). Therefore we assume that the FAA measure might not be usable if cognitive workload is induced simultaneously. We conclude that future studies should account for potential context-specifity of EEG measures.

Modulation of the attentional span by foveal and parafoveal task load: An ERP study using attentional probes.

PubMed

Kornrumpf, Benthe; Sommer, Werner

2015-09-01

Due to capacity limitation, visual attention must be focused to a limited region of the visual field. Nevertheless, it is assumed that the size of that region may vary with task demands. We aimed to obtain direct evidence for the modulation of visuospatial attention as a function of foveal and parafoveal task load. Participants were required to fixate the center word of word triplets. In separate task blocks, either just the fixated word or both the fixated and the parafoveal word to the right should be semantically classified. The spatiotemporal distribution of attention was assessed with task-irrelevant probes flashed briefly at center or parafoveal positions, during or in between word presentation trials. The N1 component of the ERP elicited by intertrial probes at possible target positions increased with task demands within a block. These results suggest the recruitment of additional attentional resources rather than a redistribution of a fixed resource pool, which persists across trials. © 2015 Society for Psychophysiological Research.

Load-Dependent Increases in Delay-Period Alpha-Band Power Track the Gating of Task-Irrelevant Inputs to Working Memory.

PubMed

Heinz, Andrew J; Johnson, Jeffrey S

2017-01-01

Studies exploring the role of neural oscillations in cognition have revealed sustained increases in alpha-band power (ABP) during the delay period of verbal and visual working memory (VWM) tasks. There have been various proposals regarding the functional significance of such increases, including the inhibition of task-irrelevant cortical areas as well as the active retention of information in VWM. The present study examines the role of delay-period ABP in mediating the effects of interference arising from on-going visual processing during a concurrent VWM task. Specifically, we reasoned that, if set-size dependent increases in ABP represent the gating out of on-going task-irrelevant visual inputs, they should be predictive with respect to some modulation in visual evoked potentials resulting from a task-irrelevant delay period probe stimulus. In order to investigate this possibility, we recorded the electroencephalogram while subjects performed a change detection task requiring the retention of two or four novel shapes. On a portion of trials, a novel, task-irrelevant bilateral checkerboard probe was presented mid-way through the delay. Analyses focused on examining correlations between set-size dependent increases in ABP and changes in the magnitude of the P1, N1 and P3a components of the probe-evoked response and how such increases might be related to behavior. Results revealed that increased delay-period ABP was associated with changes in the amplitude of the N1 and P3a event-related potential (ERP) components, and with load-dependent changes in capacity when the probe was presented during the delay. We conclude that load-dependent increases in ABP likely play a role in supporting short-term retention by gating task-irrelevant sensory inputs and suppressing potential sources of disruptive interference.

Load-Dependent Increases in Delay-Period Alpha-Band Power Track the Gating of Task-Irrelevant Inputs to Working Memory

PubMed Central

Heinz, Andrew J.; Johnson, Jeffrey S.

2017-01-01

Studies exploring the role of neural oscillations in cognition have revealed sustained increases in alpha-band power (ABP) during the delay period of verbal and visual working memory (VWM) tasks. There have been various proposals regarding the functional significance of such increases, including the inhibition of task-irrelevant cortical areas as well as the active retention of information in VWM. The present study examines the role of delay-period ABP in mediating the effects of interference arising from on-going visual processing during a concurrent VWM task. Specifically, we reasoned that, if set-size dependent increases in ABP represent the gating out of on-going task-irrelevant visual inputs, they should be predictive with respect to some modulation in visual evoked potentials resulting from a task-irrelevant delay period probe stimulus. In order to investigate this possibility, we recorded the electroencephalogram while subjects performed a change detection task requiring the retention of two or four novel shapes. On a portion of trials, a novel, task-irrelevant bilateral checkerboard probe was presented mid-way through the delay. Analyses focused on examining correlations between set-size dependent increases in ABP and changes in the magnitude of the P1, N1 and P3a components of the probe-evoked response and how such increases might be related to behavior. Results revealed that increased delay-period ABP was associated with changes in the amplitude of the N1 and P3a event-related potential (ERP) components, and with load-dependent changes in capacity when the probe was presented during the delay. We conclude that load-dependent increases in ABP likely play a role in supporting short-term retention by gating task-irrelevant sensory inputs and suppressing potential sources of disruptive interference. PMID:28555099

Intake-dependent effects of cocaine self-administration on impulsive choice in a delay discounting task

PubMed Central

Mitchell, Marci R.; Weiss, Virginia G.; Ouimet, Dominique J.; Fuchs, Rita A.; Morgan, Drake; Setlow, Barry

2014-01-01

Cocaine use is associated with high levels of impulsive choice (greater discounting of delayed rewards) in humans, but the cause/effect relationships between cocaine use and impulsive choice are not fully understood. In previous work, we found that both experimenter- and self-administration of fixed quantities of cocaine caused lasting increases in impulsive choice in rats. The present study extended these findings by taking into account baseline impulsive choice prior to self-administration, and by allowing rats free access to cocaine. Male Long-Evans rats were trained in a delay discounting task in which they made discrete-trial choices between small immediate and large delayed food rewards. Half of the rats were then implanted with intravenous catheters and, following recovery, allowed to self-administer cocaine HCl (1.0 mg/kg/infusion) in 6 hour sessions over 14 days. Control rats orally self-administered a sucrose solution under similar conditions. Upon completion of self-administration training, rats remained abstinent for 3 weeks before retesting in the delay discounting task. Cocaine and control groups did not differ prior to self-administration, but afterward, the cocaine group showed greater impulsive choice (fewer choices of large, delayed rewards) than controls. Additional analyses revealed that the effects of cocaine on impulsive choice were intake-dependent; rats classified as “low intake” did not differ from controls, whereas rats classified as “high intake” were significantly more impulsive than both controls and their pre-cocaine baseline. These findings are consistent with the idea that cocaine-induced, pharmacologically based neural adaptations promote the development of impulsive decision making. PMID:24841739

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.

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.

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.

A Study of Self and Task Performance in Childcare Centres as Perceived by Caregivers under Local Administrative Organisations in Thailand

ERIC Educational Resources Information Center

Bhulpat, Cheerapan

2011-01-01

The purpose of this research was to study the opinions toward self and task performance in childcare centres as perceived by caregivers under the jurisdiction of the Local Administrative Organization. The four areas evaluated were caregiver characteristics, task performance, objectives of caregiving and educating young children and problems and…

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

An Increase in Postural Load Facilitates an Anterior Shift of Processing Resources to Frontal Executive Function in a Postural-Suprapostural Task

PubMed Central

Huang, Cheng-Ya; Chang, Gwo-Ching; Tsai, Yi-Ying; Hwang, Ing-Shiou

2016-01-01

Increase in postural-demand resources does not necessarily degrade a concurrent motor task, according to the adaptive resource-sharing hypothesis of postural-suprapostural dual-tasking. This study investigated how brain networks are organized to optimize a suprapostural motor task when the postural load increases and shifts postural control into a less automatic process. Fourteen volunteers executed a designated force-matching task from a level surface (a relative automatic process in posture) and from a stabilometer board while maintaining balance at a target angle (a relatively controlled process in posture). Task performance of the postural and suprapostural tasks, synchronization likelihood (SL) of scalp EEG, and graph-theoretical metrics were assessed. Behavioral results showed that the accuracy and reaction time of force-matching from a stabilometer board were not affected, despite a significant increase in postural sway. However, force-matching in the stabilometer condition showed greater local and global efficiencies of the brain networks than force-matching in the level-surface condition. Force-matching from a stabilometer board was also associated with greater frontal cluster coefficients, greater mean SL of the frontal and sensorimotor areas, and smaller mean SL of the parietal-occipital cortex than force-matching from a level surface. The contrast of supra-threshold links in the upper alpha and beta bands between the two stance conditions validated load-induced facilitation of inter-regional connections between the frontal and sensorimotor areas, but that contrast also indicated connection suppression between the right frontal-temporal and the parietal-occipital areas for the stabilometer stance condition. In conclusion, an increase in stance difficulty alters the neurocognitive processes in executing a postural-suprapostural task. Suprapostural performance is not degraded by increase in postural load, due to (1) increased effectiveness of information

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.

Notes From the Field: Secondary Task Precision for Cognitive Load Estimation During Virtual Reality Surgical Simulation Training.

PubMed

Rasmussen, Sebastian R; Konge, Lars; Mikkelsen, Peter T; Sørensen, Mads S; Andersen, Steven A W

2016-03-01

Cognitive load (CL) theory suggests that working memory can be overloaded in complex learning tasks such as surgical technical skills training, which can impair learning. Valid and feasible methods for estimating the CL in specific learning contexts are necessary before the efficacy of CL-lowering instructional interventions can be established. This study aims to explore secondary task precision for the estimation of CL in virtual reality (VR) surgical simulation and also investigate the effects of CL-modifying factors such as simulator-integrated tutoring and repeated practice. Twenty-four participants were randomized for visual assistance by a simulator-integrated tutor function during the first 5 of 12 repeated mastoidectomy procedures on a VR temporal bone simulator. Secondary task precision was found to be significantly lower during simulation compared with nonsimulation baseline, p < .001. Contrary to expectations, simulator-integrated tutoring and repeated practice did not have an impact on secondary task precision. This finding suggests that even though considerable changes in CL are reflected in secondary task precision, it lacks sensitivity. In contrast, secondary task reaction time could be more sensitive, but requires substantial postprocessing of data. Therefore, future studies on the effect of CL modifying interventions should weigh the pros and cons of the various secondary task measurements. © The Author(s) 2015.

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.

Changes in Plantar Loading Based on Shoe Type and Sex During a Jump-Landing Task

PubMed Central

DeBiasio, Justin C.; Russell, Mary E.; Butler, Robert J.; Nunley, James A.; Queen, Robin M.

2013-01-01

Context: Metatarsal stress fractures are common in cleated-sport athletes. Previous authors have shown that plantar loading varies with footwear, sex, and the athletic task. Objective: To examine the effects of shoe type and sex on plantar loading in the medial midfoot (MMF), lateral midfoot (LMF), medial forefoot (MFF), middle forefoot (MidFF), and lateral forefoot (LFF) during a jump-landing task. Design: Crossover study. Setting: Laboratory. Patients or Other Participants: Twenty-seven recreational athletes (14 men, 13 women) with no history of lower extremity injury in the last 6 months and no history of foot or ankle surgery. Main Outcome Measure(s): The athletes completed 7 jumping trials while wearing bladed-cleat, turf-cleat, and running shoes. Maximum force, contact area, contact time, and the force-time integral were analyzed in each foot region. We calculated 2 × 3 analyses of variance (α = .05) to identify shoe-condition and sex differences. Results: We found no shoe × sex interactions, but the MMF, LMF, MFF, and LFF force-time integrals were greater in men (P < .03). The MMF maximum force was less with the bladed-cleat shoes (P = .02). Total foot and MidFF maximum force was less with the running shoes (P < .01). The MFF and LFF maximum forces were different among all shoe conditions (P < .01). Total foot contact area was less in the bladed-cleat shoes (P = .01). The MMF contact area was greatest in the running shoes (P < .01). The LFF contact area was less in the running shoes (P = .03). The MFF and LFF force-time integrals were greater with the bladed-cleat shoes (P < .01). The MidFF force-time integral was less in the running shoes (P < .01). Conclusions: Independent of shoe, men and women loaded the foot differently during a jump landing. The bladed cleat increased forefoot loading, which may increase the risk for forefoot injury. The type of shoe should be considered when choosing footwear for athletes returning to activity after metatarsal

Changes in plantar loading based on shoe type and sex during a jump-landing task.

PubMed

Debiasio, Justin C; Russell, Mary E; Butler, Robert J; Nunley, James A; Queen, Robin M

2013-01-01

Metatarsal stress fractures are common in cleated-sport athletes. Previous authors have shown that plantar loading varies with footwear, sex, and the athletic task. To examine the effects of shoe type and sex on plantar loading in the medial midfoot (MMF), lateral midfoot (LMF), medial forefoot (MFF), middle forefoot (MidFF), and lateral forefoot (LFF) during a jump-landing task. Crossover study. Laboratory. Twenty-seven recreational athletes (14 men, 13 women) with no history of lower extremity injury in the last 6 months and no history of foot or ankle surgery. The athletes completed 7 jumping trials while wearing bladed-cleat, turf-cleat, and running shoes. Maximum force, contact area, contact time, and the force-time integral were analyzed in each foot region. We calculated 2 × 3 analyses of variance (α = .05) to identify shoe-condition and sex differences. We found no shoe × sex interactions, but the MMF, LMF, MFF, and LFF force-time integrals were greater in men (P < .03). The MMF maximum force was less with the bladed-cleat shoes (P = .02). Total foot and MidFF maximum force was less with the running shoes (P < .01). The MFF and LFF maximum forces were different among all shoe conditions (P < .01). Total foot contact area was less in the bladed-cleat shoes (P = .01). The MMF contact area was greatest in the running shoes (P < .01). The LFF contact area was less in the running shoes (P = .03). The MFF and LFF force-time integrals were greater with the bladed-cleat shoes (P < .01). The MidFF force-time integral was less in the running shoes (P < .01). Independent of shoe, men and women loaded the foot differently during a jump landing. The bladed cleat increased forefoot loading, which may increase the risk for forefoot injury. The type of shoe should be considered when choosing footwear for athletes returning to activity after metatarsal stress fractures.

Task Integration Facilitates Multitasking.

PubMed

de Oliveira, Rita F; Raab, Markus; Hegele, Mathias; Schorer, Jörg

2017-01-01

The aim of this study was to investigate multi-task integration in a continuous tracking task. We were particularly interested in how manipulating task structure in a dual-task situation affects learning of a constant segment embedded in a pursuit-tracking task. Importantly, we examined if dual-task effects could be attributed to task integration by varying the structural similarity and difficulty of the primary and secondary tasks. In Experiment 1 participants performed a pursuit tracking task while counting high-pitched tones and ignoring low-pitched tones. The tones were either presented randomly or structurally 250 ms before each tracking turn. Experiment 2 increased the motor load of the secondary tasks by asking participants to tap their feet to the tones. Experiment 3 further increased motor load of the primary task by increasing its speed and having participants tracking with their non-dominant hand. The results show that dual-task interference can be moderated by secondary task conditions that match the structure of the primary task. Therefore our results support proposals of task integration in continuous tracking paradigms. We conclude that multi-tasking is not always detrimental for motor learning but can be facilitated through task-integration.

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.

Local administration of curcumin-loaded nanoparticles effectively inhibits inflammation and bone resorption associated with experimental periodontal disease.

PubMed

Zambrano, Laura M G; Brandao, Dayane A; Rocha, Fernanda R G; Marsiglio, Raquel P; Longo, Ieda B; Primo, Fernando L; Tedesco, Antonio C; Guimaraes-Stabili, Morgana R; Rossa Junior, Carlos

2018-04-27

There is evidence indicating that curcumin has multiple biological activities, including anti-inflammatory properties. In vitro and in vivo studies demonstrate that curcumin may attenuate inflammation and the connective tissue destruction associated with periodontal disease. Most of these studies use systemic administration, and considering the site-specific nature of periodontal disease and also the poor pharmacodynamic properties of curcumin, we conducted this proof of principle study to assess the biological effect of the local administration of curcumin in a nanoparticle vehicle on experimental periodontal disease. We used 16 rats divided into two groups of 8 animals according to the induction of experimental periodontal disease by bilateral injections of LPS or of the vehicle control directly into the gingival tissues 3×/week for 4 weeks. The same volume of curcumin-loaded nanoparticles or of nanoparticle vehicle was injected into the same sites 2×/week. µCT analysis showed that local administration of curcumin resulted in a complete inhibition of inflammatory bone resorption and in a significant decrease of both osteoclast counts and of the inflammatory infiltrate; as well as a marked attenuation of p38 MAPK and NF-kB activation. We conclude that local administration of curcumin-loaded nanoparticles effectively inhibited inflammation and bone resorption associated with experimental periodontal disease.

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.

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.

Processing Demands Impact 3-Year-Olds' Performance in a Spontaneous-Response Task: New Evidence for the Processing-Load Account of Early False-Belief Understanding.

PubMed

Scott, Rose M; Roby, Erin

2015-01-01

Prior to age four, children succeed in non-elicited-response false-belief tasks but fail elicited-response false-belief tasks. To explain this discrepancy, the processing-load account argues that the capacity to represent beliefs emerges in infancy, as indicated by early success on non-elicited-response tasks, but that children's ability to demonstrate this capacity depends on the processing demands of the task and children's processing skills. When processing demands exceed young children's processing abilities, such as in standard elicited-response tasks, children fail despite their capacity to represent beliefs. Support for this account comes from recent evidence that reducing processing demands improves young children's performance: when demands are sufficiently reduced, 2.5-year-olds succeed in elicited-response tasks. Here we sought complementary evidence for the processing-load account by examining whether increasing processing demands impeded children's performance in a non-elicited-response task. 3-year-olds were tested in a preferential-looking task in which they heard a change-of-location false-belief story accompanied by a picture book; across children, we manipulated the amount of linguistic ambiguity in the story. The final page of the book showed two images: one that was consistent with the main character's false belief and one that was consistent with reality. When the story was relatively unambiguous, children looked reliably longer at the false-belief-consistent image, successfully demonstrating their false-belief understanding. When the story was ambiguous, however, this undermined children's performance: looking times to the belief-consistent image were correlated with verbal ability, and only children with verbal skills in the upper quartile of the sample demonstrated a significant preference for the belief-consistent image. These results support the processing-load account by demonstrating that regardless of whether a task involves an elicited

Processing Demands Impact 3-Year-Olds’ Performance in a Spontaneous-Response Task: New Evidence for the Processing-Load Account of Early False-Belief Understanding

PubMed Central

Scott, Rose M.; Roby, Erin

2015-01-01

Prior to age four, children succeed in non-elicited-response false-belief tasks but fail elicited-response false-belief tasks. To explain this discrepancy, the processing-load account argues that the capacity to represent beliefs emerges in infancy, as indicated by early success on non-elicited-response tasks, but that children’s ability to demonstrate this capacity depends on the processing demands of the task and children’s processing skills. When processing demands exceed young children’s processing abilities, such as in standard elicited-response tasks, children fail despite their capacity to represent beliefs. Support for this account comes from recent evidence that reducing processing demands improves young children’s performance: when demands are sufficiently reduced, 2.5-year-olds succeed in elicited-response tasks. Here we sought complementary evidence for the processing-load account by examining whether increasing processing demands impeded children’s performance in a non-elicited-response task. 3-year-olds were tested in a preferential-looking task in which they heard a change-of-location false-belief story accompanied by a picture book; across children, we manipulated the amount of linguistic ambiguity in the story. The final page of the book showed two images: one that was consistent with the main character’s false belief and one that was consistent with reality. When the story was relatively unambiguous, children looked reliably longer at the false-belief-consistent image, successfully demonstrating their false-belief understanding. When the story was ambiguous, however, this undermined children’s performance: looking times to the belief-consistent image were correlated with verbal ability, and only children with verbal skills in the upper quartile of the sample demonstrated a significant preference for the belief-consistent image. These results support the processing-load account by demonstrating that regardless of whether a task

Load induced blindness.

PubMed

Macdonald, James S P; Lavie, Nilli

2008-10-01

Although the perceptual load theory of attention has stimulated a great deal of research, evidence for the role of perceptual load in determining perception has typically relied on indirect measures that infer perception from distractor effects on reaction times or neural activity (see N. Lavie, 2005, for a review). Here we varied the level of perceptual load in a letter-search task and assessed its effect on the conscious perception of a search-irrelevant shape stimulus appearing in the periphery, using a direct measure of awareness (present/absent reports). Detection sensitivity (d') was consistently reduced with high, compared to low, perceptual load but was unaffected by the level of working memory load. Because alternative accounts in terms of expectation, memory, response bias, and goal-neglect due to the more strenuous high load task were ruled out, these experiments clearly demonstrate that high perceptual load determines conscious perception, impairing the ability to merely detect the presence of a stimulus--a phenomenon of load induced blindness.

Rhesus monkeys employ a procedural strategy to reduce working memory load in a self-ordered spatial search task

PubMed Central

Taffe, Michael A.; Taffe, William J.

2011-01-01

Several nonhuman primate species have been reported to employ a distance-minimizing, traveling salesman-like, strategy during foraging as well as in experimental spatial search tasks involving lesser amounts of locomotion. Spatial sequencing may optimize performance by reducing reference or episodic memory loads, locomotor costs, competition or other demands. A computerized self-ordered spatial search (SOSS) memory task has been adapted from a human neuropsychological testing battery (CANTAB, Cambridge Cognition, Ltd) for use in monkeys. Accurate completion of a trial requires sequential responses to colored boxes in two or more spatial locations without repetition of a previous location. Marmosets have been reported to employ a circling pattern of search, suggesting spontaneous adoption of a strategy to reduce working memory load. In this study the SOSS performance of rhesus monkeys was assessed to determine if the use of a distance-minimizing search path enhances accuracy. A novel strategy score, independent of the trial difficulty and arrangement of boxes, has been devised. Analysis of the performance of 21 monkeys trained on SOSS over two years shows that a distance-minimizing search strategy is associated with improved accuracy. This effect is observed within individuals as they improve over many cumulative sessions of training on the task and across individuals at any given level of training. Erroneous trials were associated with a failure to deploy the strategy. It is concluded that the effect of utilizing the strategy on this locomotion-free, laboratory task is to enhance accuracy by reducing demands on spatial working memory resources. PMID:21840507

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.

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.

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.

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.

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

Administration of tauroursodeoxycholic acid prevents endothelial dysfunction caused by an oral glucose load

PubMed Central

Walsh, Lauren K.; Restaino, Robert M.; Neuringer, Martha; Manrique, Camila; Padilla, Jaume

2017-01-01

Postprandial hyperglycemia leads to a transient impairment in endothelial function; however, the mechanisms remain largely unknown. Previous work in cell culture models demonstrate that high glucose results in endoplasmic reticulum (ER) stress and, in animal studies, ER stress has been implicated as a cause of endothelial dysfunction. Herein we tested the hypothesis that acute oral administration of tauroursodeoxycholic acid (TUDCA, 1500mg), a chemical chaperone known to alleviate ER stress, would prevent hyperglycemia-induced endothelial dysfunction. In 12 young healthy subjects (seven men, five women), brachial artery flow-mediated dilation (FMD) was assessed at baseline, 1 hour, and 2 hours post an oral glucose challenge. Subjects were tested on two separate visits in a single-blind randomized crossover design: after oral ingestion of TUDCA or placebo capsules. FMD was reduced from baseline during hyperglycemia under the placebo condition (−32% at 1 hr and −28% at 2 hr post oral glucose load; p<0.05 from baseline) but not under the TUDCA condition (−4% at 1 hr and +0.3% at 2 hr post oral glucose load; p>0.05 from baseline). Postprandial plasma glucose and insulin were not altered by TUDCA ingestion. Plasma oxidative stress markers 3-nitrotyrosine and TBARs remained unaltered throughout the oral glucose challenge in both conditions. These results suggest that hyperglycemia-induced endothelial dysfunction can be mitigated by oral administration of TUDCA, thus supporting the hypothesis that ER stress may contribute to endothelial dysfunction during postprandial hyperglycemia. PMID:27503949

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.

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.

Evaluation of divided attention psychophysical task performance and effects on pupil sizes following smoked, vaporized and oral cannabis administration.

PubMed

Newmeyer, Matthew N; Swortwood, Madeleine J; Taylor, Megan E; Abulseoud, Osama A; Woodward, Thomas H; Huestis, Marilyn A

2017-08-01

Establishing science-based driving per se blood Δ 9 -tetrahydrocannabinol (THC) limits is challenging, in part because of prolonged THC detection in chronic, frequent users. Therefore, documenting observable signs of impairment is important for driving under the influence of drugs. We evaluated frequent and occasional cannabis smokers' performance on the modified Romberg balance, one leg stand (OLS), and walk and turn (WAT) tasks, and pupil size effects following controlled placebo (0.001% THC), smoked, vaporized and oral (6.9% [~50.4 mg] THC) cannabis administration. Significant effects following inhaled doses were not observed due to delayed tasks administration 1.5 and 3.5 h post-dose, but significant impairment was observed after oral dosing (blood THC concentrations peaked 1.5-3.5 h post-dose). Occasional smokers' odds of exhibiting ≥2 clues on the OLS or WAT following oral dosing were 6.4 (95% CI 2.3-18.4) times higher than after placebo, with THC and 11-hydroxy-THC blood concentrations individually producing odds ratios of 1.3 (1.1-1.5) and 1.5 (1.3-1.8) for impairment in these tasks, respectively. Pupil sizes after oral dosing under the direct lighting condition were significantly larger than after placebo by mean (SE, 95% CI) 0.4 (0.1, 0.2-0.6) mm at 1.5 h and 0.5 (0.2, 0.2-0.8) mm at 3.5 h among all participants. Oral cannabis administration impaired occasional cannabis users' performance on the OLS and WAT tasks compared to placebo, supporting other reports showing these tasks are sensitive to cannabis-related impairment. Occasional smokers' impairment was related to blood THC and 11-hydroxy-THC concentrations. These are important public health policy findings as consumption of edible cannabis products increases. Published 2017. This article is a U.S. Government work and is in the public domain in the USA. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Booster Interface Loads

NASA Technical Reports Server (NTRS)

Gentz, Steve; Wood, Bill; Nettles, Mindy

2015-01-01

The interaction between shock waves and the wake shed from the forward booster/core attach hardware results in unsteady pressure fluctuations, which can lead to large buffeting loads on the vehicle. This task investigates whether computational tools can adequately predict these flows, and whether alternative booster nose shapes can reduce these loads. Results from wind tunnel tests will be used to validate the computations and provide design information for future Space Launch System (SLS) configurations. The current work combines numerical simulations with wind tunnel testing to predict buffeting loads caused by the boosters. Variations in nosecone shape, similar to the Ariane 5 design (fig. 1), are being evaluated with regard to lowering the buffet loads. The task will provide design information for the mitigation of buffet loads for SLS, along with validated simulation tools to be used to assess future SLS designs.

Effects of domain-specific exercise load on speed and accuracy of a domain-specific perceptual-cognitive task.

PubMed

Schapschröer, M; Baker, J; Schorer, J

2016-08-01

In the context of perceptual-cognitive expertise it is important to know whether physiological loads influence perceptual-cognitive performance. This study examined whether a handball specific physical exercise load influenced participants' speed and accuracy in a flicker task. At rest and during a specific interval exercise of 86.5-90% HRmax, 35 participants (experts: n=8, advanced: n=13, novices, n=14) performed a handball specific flicker task with two types of patterns (structured and unstructured). For reaction time, results revealed moderate effect sizes for group, with experts reacting faster than advanced and advanced reacting faster than novices, and for structure, with structured videos being performed faster than unstructured ones. A significant interaction for structure×group was also found, with experts and advanced players faster for structured videos, and novices faster for unstructured videos. For accuracy, significant main effects were found for structure with structured videos solved more accurately. A significant interaction for structure×group was revealed, with experts and advanced more accurate for structured scenes and novices more accurate for unstructured scenes. A significant interaction was also found for condition×structure; at rest, unstructured and structured scenes were performed with the same accuracy while under physical exercise, structured scenes were solved more accurately. No other interactions were found. These results were somewhat surprising given previous work in this area, although the impact of a specific physical exercise on a specific perceptual-cognitive task may be different from those tested generally. 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.

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

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.

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…

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.

CNA-loaded PLGA nanoparticles improve humoral response againstS. aureus-mediated infections in a mouse model: subcutaneous vs. nasal administration strategy.

PubMed

Genta, Ida; Colonna, Claudia; Conti, Bice; Caliceti, Paolo; Salmaso, Stefano; Speziale, Pietro; Pietrocola, Giampiero; Chiesa, Enrica; Modena, Tiziana; Dorati, Rossella

2016-12-01

The aim of this work was the assessment of the "in vivo" immune response of a poly(lactide-co-glycolide)-based nanoparticulate adjuvant for a sub-unit vaccine, namely, a purified recombinant collagen-binding bacterial adhesion fragment (CNA19), against Staphylococcus aureus-mediated infections. "In vivo" immunogenicity studies were performed on mice: immunisation protocols encompassed subcutaneous and intranasal administration of CNA19 formulated as nanoparticles (NPs) and furthermore, CNA19-loaded NPs formulated in a set-up thermosetting chitosan-β-glycerolphosphate (chitosan-β-GP) solution for intranasal route in order to extend antigen exposure to nasal mucosa. CNA19 loaded NPs (mean size of about 195 nm, 9.04 ± 0.37μg/mg as CNA19 loading capacity) confirmed as suitable vaccine for subcutaneous administration with a more pronounced adjuvant effect (about 3-fold higher) with respect to aluminium, recognised as "reference" adjuvant. CNA19 loaded NPs formulated in an optimised thermogelling chitosan-β-GP solution showed promising results for eliciting an effective humoral response and a good chance as intranasal boosting dose.

Spatial working memory in aging and mild cognitive impairment: effects of task load and contextual cueing.

PubMed

Kessels, Roy P C; Meulenbroek, Olga; Fernández, Guillén; Olde Rikkert, Marcel G M

2010-09-01

Mild Cognitive Impairment (MCI) is characterized by episodic memory deficits, while aspects of working memory may also be implicated, but studies into this latter domain are scarce and results are inconclusive. Using a computerized search paradigm, this study compares 25 young adults, 25 typically aging older adults and 15 amnestic MCI patients as to their working-memory capacities for object-location information and potential differential effects of memory load and additional context cues. An age-related deficit in visuospatial working-memory maintenance was found that became more pronounced with increasing task demands. The MCI group additionally showed reduced maintenance of bound information, i.e., object-location associations, again especially at elevated memory load. No effects of contextual cueing were found. The current findings indicate that working memory should be considered when screening patients for suspected MCI and monitoring its progression.

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

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.

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.

Secondary task for full flight simulation incorporating tasks that commonly cause pilot error: Time estimation

NASA Technical Reports Server (NTRS)

Rosch, E.

1975-01-01

The task of time estimation, an activity occasionally performed by pilots during actual flight, was investigated with the objective of providing human factors investigators with an unobtrusive and minimally loading additional task that is sensitive to differences in flying conditions and flight instrumentation associated with the main task of piloting an aircraft simulator. Previous research indicated that the duration and consistency of time estimates is associated with the cognitive, perceptual, and motor loads imposed by concurrent simple tasks. The relationships between the length and variability of time estimates and concurrent task variables under a more complex situation involving simulated flight were clarified. The wrap-around effect with respect to baseline duration, a consequence of mode switching at intermediate levels of concurrent task distraction, should contribute substantially to estimate variability and have a complex effect on the shape of the resulting distribution of estimates.

The Effects of Task-Induced Involvement Load on Word Learning and Confidence Judgments Mediated by Knowledge and Regulation of Cognition

ERIC Educational Resources Information Center

Teng, Feng

2017-01-01

The relationships between knowledge and regulation of cognition and how they interact to mediate the effects of task-induced involvement load on word learning and confidence judgments were investigated. The participants were 77 undergraduate English majors. They were required to complete a checklist on metacognition. Subsequently, they were…

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.

Is Borg's perceived exertion scale a useful indicator of muscular and cardiovascular load in blue-collar workers with lifting tasks? A cross-sectional workplace study.

PubMed

Jakobsen, Markus Due; Sundstrup, Emil; Persson, Roger; Andersen, Christoffer H; Andersen, Lars L

2014-02-01

To investigate associations between perceived exertion and objectively assessed muscular and cardiovascular load during a full working day among workers with manual lifting tasks. A total of 159 men and 41 women from 14 workplaces with manual lifting tasks participated. Participants reported perceived exertion (BORG-CR10) at midday and after work. Surface electromyography of the thigh, lower back and neck muscles were normalized to isometric voluntary contractions (MVC) to express relative muscle load during the day. Cardiovascular load was measured with electrocardiography and calculated as the average percentage of the heart rate reserve capacity (((heart rate during work - resting heart rate) / (maximum heart rate - resting heart rate)) * 100) during the day. Using linear regression, significant but weak associations (β < 0.23) were observed between perceived exertion and (1) high muscle activity (>60% of MVC) of the neck muscles and (2) inactivity (<1% of MVC) of the thigh muscles and (3) cardiovascular load, respectively. Using logistic regression, perceived exertion ≥4 (high exertion), referencing <4 (low-to-moderate exertion), was related to high activity of the trapezius muscle [OR 18 (95% CI 2-143)], i.e., the odds for experiencing high exertion during work increased 18-fold for each percentage increase in time above 60% MVC. During a full working day among blue-collar workers with lifting tasks, high neck muscle activity increases the odds for experiencing high perceived physical exertion. Perceived exertion of at least 4 on the BORG CR10 scale appears to be a good indicator that high muscular loading occurs.

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.

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

Measurement of functional task difficulty during motor learning: What level of difficulty corresponds to the optimal challenge point?

PubMed

Akizuki, Kazunori; Ohashi, Yukari

2015-10-01

The relationship between task difficulty and learning benefit was examined, as was the measurability of task difficulty. Participants were required to learn a postural control task on an unstable surface at one of four different task difficulty levels. Results from the retention test showed an inverted-U relationship between task difficulty during acquisition and motor learning. The second-highest level of task difficulty was the most effective for motor learning, while learning was delayed at the most and least difficult levels. Additionally, the results indicate that salivary α-amylase and the performance dimension of the National Aeronautics and Space Administration-Task Load Index (NASA-TLX) are useful indices of task difficulty. Our findings suggested that instructors may be able to adjust task difficulty based on salivary α-amylase and the performance dimension of the NASA-TLX to enhance learning. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

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

Do Cheaters Never Prosper? The Impact of Examples, Expertise, and Cognitive Load on Cryptomnesia and Inadvertent Self-Plagiarism of Creative Tasks

ERIC Educational Resources Information Center

Dow, Gayle T.

2015-01-01

Previous work has shown that the presence of examples may lead to cryptomnesia, or inadvertent plagiarism, on creative tasks. Various experiential and environmental attributes may magnify this finding. For instance, novices, with limited knowledge, may be more prone to inadvertently plagiarize examples, and increases in cognitive load may result…

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.

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

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.

Influence of snow shovel shaft configuration on lumbosacral biomechanics during a load-lifting task.

PubMed

Lewinson, Ryan T; Rouhi, Gholamreza; Robertson, D Gordon E

2014-03-01

Lower-back injury from snow shovelling may be related to excessive joint loading. Bent-shaft snow shovels are commonly available for purchase; however, their influence on lower back-joint loading is currently not known. Therefore, the purpose of this study was to compare L5/S1 extension angular impulses between a bent-shaft and a standard straight-shaft snow shovel. Eight healthy subjects participated in this study. Each completed a simulated snow-lifting task in a biomechanics laboratory with each shovel design. A standard motion analysis procedure was used to determine L5/S1 angular impulses during each trial, as well as peak L5/S1 extension moments and peak upper body flexion angle. Paired-samples t-tests (α = 0.05) were used to compare variables between shovel designs. Correlation was used to determine the relationship between peak flexion and peak moments. Results of this study show that the bent-shaft snow shovel reduced L5/S1 extension angular impulses by 16.5% (p = 0.022), decreased peak moments by 11.8% (p = 0.044), and peak flexion by 13.0% (p = 0.002) compared to the straight-shaft shovel. Peak L5/S1 extension moment magnitude was correlated with peak upper body flexion angle (r = 0.70). Based on these results, it is concluded that the bent-shaft snow shovel can likely reduce lower-back joint loading during snow shovelling, and thus may have a role in snow shovelling injury prevention. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Design of an Adaptive Human-Machine System Based on Dynamical Pattern Recognition of Cognitive Task-Load.

PubMed

Zhang, Jianhua; Yin, Zhong; Wang, Rubin

2017-01-01

This paper developed a cognitive task-load (CTL) classification algorithm and allocation strategy to sustain the optimal operator CTL levels over time in safety-critical human-machine integrated systems. An adaptive human-machine system is designed based on a non-linear dynamic CTL classifier, which maps a set of electroencephalogram (EEG) and electrocardiogram (ECG) related features to a few CTL classes. The least-squares support vector machine (LSSVM) is used as dynamic pattern classifier. A series of electrophysiological and performance data acquisition experiments were performed on seven volunteer participants under a simulated process control task environment. The participant-specific dynamic LSSVM model is constructed to classify the instantaneous CTL into five classes at each time instant. The initial feature set, comprising 56 EEG and ECG related features, is reduced to a set of 12 salient features (including 11 EEG-related features) by using the locality preserving projection (LPP) technique. An overall correct classification rate of about 80% is achieved for the 5-class CTL classification problem. Then the predicted CTL is used to adaptively allocate the number of process control tasks between operator and computer-based controller. Simulation results showed that the overall performance of the human-machine system can be improved by using the adaptive automation strategy proposed.

Administrative Synergy

ERIC Educational Resources Information Center

Hewitt, Kimberly Kappler; Weckstein, Daniel K.

2012-01-01

One of the biggest obstacles to overcome in creating and sustaining an administrative professional learning community (PLC) is time. Administrators are constantly deluged by the tyranny of the urgent. It is a Herculean task to carve out time for PLCs, but it is imperative to do so. In this article, the authors describe how an administrative PLC…

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.

A meta-analytic review of the impact of intranasal oxytocin administration on cortisol concentrations during laboratory tasks: moderation by method and mental health.

PubMed

Cardoso, Christopher; Kingdon, Danielle; Ellenbogen, Mark A

2014-11-01

A large body of research has examined the acute effects of intranasal oxytocin administration on social cognition and stress-regulation. While progress has been made with respect to understanding the effect of oxytocin administration on social cognition in clinical populations (e.g. autism, schizophrenia), less is known about its impact on the functioning of the hypothalamic-pituitary-adrenal (HPA) axis among individuals with a mental disorder. We conducted a meta-analysis on the acute effect of intranasal oxytocin administration on the cortisol response to laboratory tasks. The search yielded eighteen studies employing a randomized, placebo-controlled design (k=18, N=675). Random-effects models and moderator analyses were performed using the metafor package for the statistical program R. The overall effect size estimate was modest and not statistically significant (Hedges g=-0.151, p=0.11) with moderate heterogeneity in this effect across studies (I(2)=31%). Controlling for baseline differences in cortisol concentrations, moderation analyses revealed that this effect was larger in response to challenging laboratory tasks that produced a robust stimulation of the HPA-axis (Hedges g=-0.433, 95% CI[-0.841, -0.025]), and in clinical populations relative to healthy controls (Hedges g=-0.742, 95% CI[-1.405, -0.078]). Overall, oxytocin administration showed greater attenuation of the cortisol response to laboratory tasks that strongly activated the HPA-axis, relative to tasks that did not. The effect was more robust among clinical populations, suggesting possible increased sensitivity to oxytocin among those with a clinical diagnosis and concomitant social difficulties. These data support the view that oxytocin may play an important role in HPA dysfunction associated with psychopathology. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

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.

Scalability of Robotic Controllers: Effects of Progressive Levels of Autonomy on Robotic Reconnaissance Tasks

DTIC Science & Technology

2010-08-01

facility. 2.2.4 The National Aeronautics and Space Administration-Task Load Index (NASA-TLX) The NASA-TLX is a subjective workload assessment tool ...No 6 NR If so, what type? Davinci (1) 14. Please describe the conditions under which you used the robotic system. Surgical (1) 15...2 Fantastic tool . Can see how this will save more lives by using the robot as the recon tool . 1 Interesting and fun. 3 Easily understood what to

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 (�

Establishing Immediate Reliability of Sonographic Measurements of the Transversus Abdominis in Asymptomatic Adults Performing Upright Loaded Functional Tasks in a Clinical Context Without Delayed Recorded Measurement.

PubMed

McPherson, Sue; Watson, Todd; Pate, Lindsey

2016-08-01

This study examined the reliability of sonographic measurements of the transversus abdominis of adults without low back pain during upright loaded functional tasks in real time, without relying on delayed recorded images. A single-group repeated-measures reliability study was conducted on 12 healthy participants without low back pain. Six of these adults reported a prior history of abdominal drawing-in maneuver training without sonographic measurement. The participants performed 3 trials of neutral standing, a loaded forward reach, and a loaded box lift under rest and with abdominal drawing-in maneuver instructions; task order was randomized. Transversus abdominis thickness measurements were obtained by an experienced rater using B-mode sonography in real-time via electronic calipers twice on the same static image during all trials by a rater. The rater was masked to group assignment and on-screen measurement output and required to respond to trivia questions between repeated measurements. The participants included 6 male and 6 female adults with a mean age ± SD of 26.3 ± 3.7 years. Intra-rater intraclass correlation coefficients (2,3) were high and precise for the rater's first and second measurements for all tasks and instruction conditions for mean transversus abdominis thickness and percent change in thickness measurements (eg, ranges were 0.968-0.997 for intraclass correlation coefficients, 0.01-0.21 mm for standard errors of the measurement, and 0.01-0.58 mm for minimal detectable changes). Calipers cleared by the rater or a research assistant produced similar findings of excellent reliability and precision. High intra-rater reliability and precision of transversus abdominis thickness measurements were obtained by a physical therapist in real time from asymptomatic adults performing upright loaded functional tasks under rest and with abdominal drawing-in maneuver instructions.

Concurrent Performance of Gunner’s and Robotic Operator’s Tasks in a Simulated Mounted Combat System Environment

DTIC Science & Technology

2006-06-01

Appendix A. Demographic Questionnaire 25 Appendix B. Attentional Control Survey 27 Appendix C. NASA - TLX Questionnaire 29 Appendix D. Simulator...the National Aeronautics and Space Administration task load index ( NASA - TLX ) questionnaire (appendix C) (Hart & Staveland, 1988). The NASA - TLX is a...There were 2-minute breaks between experimental sessions. Participants assessed their workload using the NASA - TLX after they completed each

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.

Development of Suppositories Containing Flutamide-Loaded Alginate-Tamarind Microparticles for Rectal Administration: In Vitro and in Vivo Studies.

PubMed

Patil, Bharati Shivajirao; Mahajan, Hitendra Shaligram; Surana, Sanjay Javerilal

2015-01-01

In the present work the absorption of flutamide from suppositories containing hydrophilic tamarind alginate microparticles after rectal administration in rats was investigated with the purpose of enhancing bioavailability and to avoid hepatic toxicity. Microparticles were developed by ionic gelation method and optimized using one factorial design of response surface methodology. The optimized batch of microparticles had tamarind gum-sodium alginate (1 : 3) ratio and showed entrapment efficiency 94.969% and mucoadhesion strength 94.646% with desirability of 0.961. Suppositories loaded with microparticles were developed by fusion method using poloxamer 407 and poloxamer 188 in combination as suppository base. Kinetic analysis of the release data of microparticle-loaded suppositories showed time-independent release of drug. Higher values of 'n' (>0.89) represent Super Case II-type drug release. The pharmacokinetics of flutamide from flutamide tamarind alginate microparticle-loaded suppository were compared with oral suspension. Cmax of microparticle-loaded suppository was significantly larger than that of oral suspension (1.711 and 0.859 µg/mL, respectively).

Research notes : customized live-load factors for bridge load rating.

DOT National Transportation Integrated Search

2007-03-01

The state-of-the-art approach to load rating bridges is the Load and Resistance Factor Rating (LRFR) method, supported by the Federal Highway Administration and the American Association of State Highway and Transportation Officials. This approach ens...

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.

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…

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 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.

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…

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.

Medial knee loading is altered in subjects with early osteoarthritis during gait but not during step-up-and-over task

PubMed Central

Wesseling, Mariska; Smith, Colin R.; Thelen, Darryl G.; Verschueren, Sabine; Jonkers, Ilse

2017-01-01

This study evaluates knee joint loading during gait and step-up-and-over tasks in control subjects, subjects with early knee OA and those with established knee OA. Thirty-seven subjects with varying degrees of medial compartment knee OA severity (eighteen with early OA and sixteen with established OA), and nineteen healthy controls performed gait and step-up-and-over tasks. Knee joint moments, contact forces (KCF), the magnitude of contact pressures and center of pressure (CoP) location were analyzed for the three groups for both activities using a multi-body knee model with articular cartilage contact, 14 ligaments, and six degrees of freedom tibiofemoral and patellofemoral joints. During gait, the first peak of the medial KCF was significantly higher for patients with early knee OA (p = 0.048) and established knee OA (p = 0.001) compared to control subjects. Furthermore, the medial contact pressure magnitudes and CoP location were significantly different in both groups of patients compared to controls. Knee rotation moments (KRMs) and external rotation angles were significantly higher during early stance in both patient groups (p < 0.0001) compared to controls. During step-up-and-over, there was a high variability between the participants and no significant differences in KCF were observed between the groups. Knee joint loading and kinematics were found to be altered in patients with early knee OA only during gait. This is an indication that an excessive medial KCF and altered loading location, observed in these patients, is a contributor to early progression of knee OA. PMID:29117248

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.

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…

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…

An electromyographic and kinematic comparison between an extendable conveyor system and an articulating belt conveyor used for truck loading and unloading tasks.

PubMed

Lavender, Steven A; Nagavarapu, Shasank; Allread, W Gary

2017-01-01

Many retail distribution centers (DCs) manually load and unload boxes into or out of trailers and shipping containers. This study investigated whether an articulating belt conveyor with a height adjustable platform, positioned at the end of an extendable conveyor, significantly reduces shoulder and back muscle loading and the spine kinematics associated with these tasks. Electromyographic and kinematic data were collected from eight volunteer employees as trailers at a shoe DC were unloaded and from nine volunteer employees as trailers at an apparel DC were loaded. Participants in this repeated measures study handled boxes with a conventional powered extendable conveyor system and with the articulating belt conveyor positioned at the end of the extendable conveyor. Bilaterally the normalized activation levels of the erector spinae and anterior deltoid muscles were reduced when loading and unloading boxes with the articulating belt conveyor. Spine movement speeds were also reduced with the articulating conveyor. Copyright © 2016 Elsevier 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

Load-dependent brain activation assessed by time-domain functional near-infrared spectroscopy during a working memory task with graded levels of difficulty

NASA Astrophysics Data System (ADS)

Molteni, Erika; Contini, Davide; Caffini, Matteo; Baselli, Giuseppe; Spinelli, Lorenzo; Cubeddu, Rinaldo; Cerutti, Sergio; Bianchi, Anna Maria; Torricelli, Alessandro

2012-05-01

We evaluated frontal brain activation during a mixed attentional/working memory task with graded levels of difficulty in a group of 19 healthy subjects, by means of time-domain functional near-infrared spectroscopy (fNIRS). Brain activation was assessed, and load-related oxy- and deoxy-hemoglobin changes were studied. Generalized linear model (GLM) was applied to the data to explore the metabolic processes occurring during the mental effort and, possibly, their involvement in short-term memorization. GLM was applied to the data twice: for modeling the task as a whole and for specifically investigating brain activation at each cognitive load. This twofold employment of GLM allowed (1) the extraction and isolation of different information from the same signals, obtained through the modeling of different cognitive categories (sustained attention and working memory), and (2) the evaluation of model fitness, by inspection and comparison of residuals (i.e., unmodeled part of the signal) obtained in the two different cases. Results attest to the presence of a persistent attentional-related metabolic activity, superimposed to a task-related mnemonic contribution. Some hemispherical differences have also been highlighted frontally: deoxy-hemoglobin changes manifested a strong right lateralization, whereas modifications in oxy- and total hemoglobin showed a medial localization. The present work successfully explored the capability of fNIRS to detect the two neurophysiological categories under investigation and distinguish their activation patterns.

Opposite effects of capacity load and resolution load on distractor processing.

PubMed

Zhang, Weiwei; Luck, Steven J

2015-02-01

According to the load theory of attention, an increased perceptual load reduces distractor processing whereas an increased working memory load facilitates distractor processing. Here we raise the possibility that the critical distinction may instead be between an emphasis on resolution and an emphasis on capacity. That is, perceptual load manipulations typically emphasize resolution (fine-grained discriminations), whereas working memory load manipulations typically emphasize capacity (simultaneous processing of multiple relevant stimuli). To test the plausibility of this hypothesis, we used a visual working memory task that emphasized either the number of items to be stored (capacity load, retaining 2 vs. 4 colors) or the precision of the representations (resolution load, detecting small vs. large color changes). We found that an increased capacity load led to increased flanker interference (a measure of distractor processing), whereas an increased resolution load led to reduced flanker interference. These opposite effects of capacity load and resolution load on distractor processing mirror the previously described opposite effects of perceptual load and working memory load.

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

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.

Irinotecan-loaded double-reversible thermogel with improved antitumor efficacy without initial burst effect and toxicity for intramuscular administration.

PubMed

Din, Fakhar Ud; Kim, Dong Wuk; Choi, Ju Yeon; Thapa, Raj Kumar; Mustapha, Omer; Kim, Dong Shik; Oh, Yu-Kyoung; Ku, Sae Kwang; Youn, Yu Seok; Oh, Kyung Taek; Yong, Chul Soon; Kim, Jong Oh; Choi, Han-Gon

2017-05-01

Intramuscularly administered, anti-tumour drugs induce severe side effects due to their direct contact with body tissues and initial burst effect. In this study, to solve this problem, a novel double-reversible thermogel system (DRTG) for the intramuscular administration of irinotecan was developed. This irinotecan-loaded DRTG was prepared by dispersing the irinotecan-loaded thermoreversible solid lipid nanoparticles (SLNs) in the thermoreversible hydrogel. In DRTG, the former was solid at 25°C but converted to liquid at 36.5°C; in contrast, the latter existed in a liquid form but transformed to gel state in the body. The DRTG was easily administered intramuscularly. Its particle size and drug content were not noticeably changeable, resulting that it was stable at 40°C for at least 6months. Compared to the irinotecan-loaded solution and conventional hydrogel, the DRTG significantly delayed drug release, leading to a reduced burst effect. Moreover, it showed decreased C max and maintained the sustained plasma concentrations at a relatively low level for the long period of 60h in rats, resulting in ameliorated side effects of the anti-tumour drug. Furthermore, it gave significantly improved anti-tumour efficacy in tumour-bearing mice compared to the hydrogel but, unlike the conventional hydrogel, induced no body weight loss and local damage to the muscle. Thus, this DRTG with improved antitumor efficacy without initial burst effect and toxicity could provide a potential pharmaceutical system for the intramuscular administration of irinotecan. Intramuscularly administered, anti-tumour drugs induce severe side effects due to their direct contact with body tissues and initial burst effect. To solve this problem, we developed a novel double-reversible thermogel system (DRTG) for the intramuscular administration of irinotecan. Unlike the conventional hydrogel, the DRTG is a dispersion of the irinotecan-loaded thermoreversible solid lipid nanoparticles in the

The Administrator's Use of Microcomputer Systems.

ERIC Educational Resources Information Center

Brown, Kenneth C.

1983-01-01

The use of microcomputers by college administrators to increase productivity is discussed. Microcomputers can help increase productivity in the following administrative office tasks: decision support, communication, personal assistance, and task management. One of the most promising developments to emerge from the decision sciences over the past…

Validity and reliability of an online visual-spatial working memory task for self-reliant administration in school-aged children.

PubMed

Van de Weijer-Bergsma, Eva; Kroesbergen, Evelyn H; Prast, Emilie J; Van Luit, Johannes E H

2015-09-01

Working memory is an important predictor of academic performance, and of math performance in particular. Most working memory tasks depend on one-to-one administration by a testing assistant, which makes the use of such tasks in large-scale studies time-consuming and costly. Therefore, an online, self-reliant visual-spatial working memory task (the Lion game) was developed for primary school children (6-12 years of age). In two studies, the validity and reliability of the Lion game were investigated. The results from Study 1 (n = 442) indicated satisfactory six-week test-retest reliability, excellent internal consistency, and good concurrent and predictive validity. The results from Study 2 (n = 5,059) confirmed the results on the internal consistency and predictive validity of the Lion game. In addition, multilevel analysis revealed that classroom membership influenced Lion game scores. We concluded that the Lion game is a valid and reliable instrument for the online computerized and self-reliant measurement of visual-spatial working memory (i.e., updating).

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…

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.

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

[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.

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.

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…

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

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

Evidence for the triadic model of adolescent brain development: Cognitive load and task-relevance of emotion differentially affect adolescents and adults.

PubMed

Mueller, Sven C; Cromheeke, Sofie; Siugzdaite, Roma; Nicolas Boehler, C

2017-08-01

In adults, cognitive control is supported by several brain regions including the limbic system and the dorsolateral prefrontal cortex (dlPFC) when processing emotional information. However, in adolescents, some theories hypothesize a neurobiological imbalance proposing heightened sensitivity to affective material in the amygdala and striatum within a cognitive control context. Yet, direct neurobiological evidence is scarce. Twenty-four adolescents (12-16) and 28 adults (25-35) completed an emotional n-back working memory task in response to happy, angry, and neutral faces during fMRI. Importantly, participants either paid attention to the emotion (task-relevant condition) or judged the gender (task-irrelevant condition). Behaviorally, for both groups, when happy faces were task-relevant, performance improved relative to when they were task-irrelevant, while performance decrements were seen for angry faces. In the dlPFC, angry faces elicited more activation in adults during low relative to high cognitive load (2-back vs. 0-back). By contrast, happy faces elicited more activation in the amygdala in adolescents when they were task-relevant. Happy faces also generally increased nucleus accumbens activity (regardless of relevance) in adolescents relative to adults. Together, the findings are consistent with neurobiological models of adolescent brain development and identify neurodevelopmental differences in cognitive control emotion interactions. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

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

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.

Comparative analysis of low-back loading on chiropractors using various workstation table heights and performing various tasks.

PubMed

Lorme, Kenneth J; Naqvi, Syed A

2003-01-01

interaction between table height and task performed. Workstation table height was found to have a significant effect on low-back load of subjects under study. The results of this study demonstrate an overall unacceptably high amount of sagittal flexion, ligament strain, and disk compression force on the chiropractor subjects in the tasks performed.

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

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.

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.

Haptic-Based Perception-Empathy Biofeedback Enhances Postural Motor Learning During High-Cognitive Load Task in Healthy Older Adults

PubMed Central

Yasuda, Kazuhiro; Saichi, Kenta; Iwata, Hiroyasu

2018-01-01

Falls and fall-induced injuries are major global public health problems, and sensory input impairment in older adults results in significant limitations in feedback-type postural control. A haptic-based biofeedback (BF) system can be used for augmenting somatosensory input in older adults, and the application of this BF system can increase the objectivity of the feedback and encourage comparison with that provided by a trainer. Nevertheless, an optimal BF system that focuses on interpersonal feedback for balance training in older adults has not been proposed. Thus, we proposed a haptic-based perception-empathy BF system that provides information regarding the older adult's center-of-foot pressure pattern to the trainee and trainer for refining the motor learning effect. The first objective of this study was to examine the effect of this balance training regimen in healthy older adults performing a postural learning task. Second, this study aimed to determine whether BF training required high cognitive load to clarify its practicability in real-life settings. Twenty older adults were assigned to two groups: BF and control groups. Participants in both groups tried balance training in the single-leg stance while performing a cognitive task (i.e., serial subtraction task). Retention was tested 24 h later. Testing comprised balance performance measures (i.e., 95% confidence ellipse area and mean velocity of sway) and dual-task performance (number of responses and correct answers). Measurements of postural control using a force plate revealed that the stability of the single-leg stance was significantly lower in the BF group than in the control group during the balance task. The BF group retained the improvement in the 95% confidence ellipse area 24 h after the retention test. Results of dual-task performance during the balance task were not different between the two groups. These results confirmed the potential benefit of the proposed balance training regimen in

Haptic-Based Perception-Empathy Biofeedback Enhances Postural Motor Learning During High-Cognitive Load Task in Healthy Older Adults.

PubMed

Yasuda, Kazuhiro; Saichi, Kenta; Iwata, Hiroyasu

2018-01-01

Falls and fall-induced injuries are major global public health problems, and sensory input impairment in older adults results in significant limitations in feedback-type postural control. A haptic-based biofeedback (BF) system can be used for augmenting somatosensory input in older adults, and the application of this BF system can increase the objectivity of the feedback and encourage comparison with that provided by a trainer. Nevertheless, an optimal BF system that focuses on interpersonal feedback for balance training in older adults has not been proposed. Thus, we proposed a haptic-based perception-empathy BF system that provides information regarding the older adult's center-of-foot pressure pattern to the trainee and trainer for refining the motor learning effect. The first objective of this study was to examine the effect of this balance training regimen in healthy older adults performing a postural learning task. Second, this study aimed to determine whether BF training required high cognitive load to clarify its practicability in real-life settings. Twenty older adults were assigned to two groups: BF and control groups. Participants in both groups tried balance training in the single-leg stance while performing a cognitive task (i.e., serial subtraction task). Retention was tested 24 h later. Testing comprised balance performance measures (i.e., 95% confidence ellipse area and mean velocity of sway) and dual-task performance (number of responses and correct answers). Measurements of postural control using a force plate revealed that the stability of the single-leg stance was significantly lower in the BF group than in the control group during the balance task. The BF group retained the improvement in the 95% confidence ellipse area 24 h after the retention test. Results of dual-task performance during the balance task were not different between the two groups. These results confirmed the potential benefit of the proposed balance training regimen in

29 CFR 541.707 - Occasional tasks.

Code of Federal Regulations, 2013 CFR

2013-07-01

... DELIMITING THE EXEMPTIONS FOR EXECUTIVE, ADMINISTRATIVE, PROFESSIONAL, COMPUTER AND OUTSIDE SALES EMPLOYEES Definitions and Miscellaneous Provisions § 541.707 Occasional tasks. Occasional, infrequently recurring tasks...

29 CFR 541.707 - Occasional tasks.

Code of Federal Regulations, 2014 CFR

2014-07-01

... DELIMITING THE EXEMPTIONS FOR EXECUTIVE, ADMINISTRATIVE, PROFESSIONAL, COMPUTER AND OUTSIDE SALES EMPLOYEES Definitions and Miscellaneous Provisions § 541.707 Occasional tasks. Occasional, infrequently recurring tasks...

29 CFR 541.707 - Occasional tasks.

Code of Federal Regulations, 2012 CFR

2012-07-01

... DELIMITING THE EXEMPTIONS FOR EXECUTIVE, ADMINISTRATIVE, PROFESSIONAL, COMPUTER AND OUTSIDE SALES EMPLOYEES Definitions and Miscellaneous Provisions § 541.707 Occasional tasks. Occasional, infrequently recurring tasks...

29 CFR 541.707 - Occasional tasks.

Code of Federal Regulations, 2011 CFR

2011-07-01

... DELIMITING THE EXEMPTIONS FOR EXECUTIVE, ADMINISTRATIVE, PROFESSIONAL, COMPUTER AND OUTSIDE SALES EMPLOYEES Definitions and Miscellaneous Provisions § 541.707 Occasional tasks. Occasional, infrequently recurring tasks...

Effects of acute administration of nicotinic and muscarinic cholinergic agonists and antagonists on performance in different cost-benefit decision making tasks in rats.

PubMed

Mendez, Ian A; Gilbert, Ryan J; Bizon, Jennifer L; Setlow, Barry

2012-12-01

Alterations in cost-benefit decision making accompany numerous neuropsychiatric conditions, including schizophrenia, attention deficit hyperactivity disorder, and addiction. Central cholinergic systems have been linked to the etiology and/or treatment of many of these conditions, but little is known about the role of cholinergic signaling in cost-benefit decision making. The goal of these experiments was to determine how cholinergic signaling is involved in cost-benefit decision making, using a behavioral pharmacological approach. Male Long-Evans rats were trained in either "probability discounting" or "delay discounting" tasks, in which rats made discrete-trial choices between a small food reward and a large food reward associated with either varying probabilities of omission or varying delays to delivery, respectively. The effects of acute administration of different doses of nicotinic and muscarinic acetylcholine receptor agonists and antagonists were assessed in each task. In the probability discounting task, acute nicotine administration (1.0 mg/kg) significantly increased choice of the large risky reward, and control experiments suggested that this was due to robust nicotine-induced impairments in behavioral flexibility. In the delay discounting task, the muscarinic antagonists scopolamine (0.03, 0.1, and 0.3 mg/kg) and atropine (0.3 mg/kg) both significantly increased choice of the small immediate reward. Neither mecamylamine nor oxotremorine produced reliable effects on either of the decision making tasks. These data suggest that cholinergic receptors play multiple roles in decision making contexts which include consideration of reward delay or probability. These roles should be considered when targeting these receptors for therapeutic purposes.

Effects of force load, muscle fatigue and extremely low frequency magnetic stimulation on EEG signals during side arm lateral raise task.

PubMed

Wang, Ying; Cao, Liu; Hao, Dongmei; Rong, Yao; Yang, Lin; Zhang, Song; Chen, Fei; Zheng, Dingchang

2017-05-01

This study was to quantitatively investigate the effects of force load, muscle fatigue and extremely low frequency (ELF) magnetic stimulation on electroencephalography (EEG) signal features during side arm lateral raise task. EEG signals were recorded by a BIOSEMI Active Two system with Pin-Type active-electrodes from 18 healthy subjects when they performed the right arm side lateral raise task (90° away from the body) with three different loads (0 kg, 1 kg and 3 kg; their order was randomized among the subjects) on the forearm. The arm maintained the loads until the subject felt exhausted. The first 10 s recording for each load was regarded as non-fatigue status and the last 10 s before the subject was exhausted as fatigue status. The subject was then given a 5 min resting between different loads. Two days later, the same experiment was performed on each subject except that ELF magnetic stimulation was applied to the subject's deltoid muscle during the 5 min resting period. EEG features from C3 and C4 electrodes including the power of alpha, beta and gamma and sample entropy were analyzed and compared between different loads, non-fatigue/fatigue status, and with/without ELF magnetic stimulation. The key results were associated with the change of the power of alpha band. From both C3-EEG and C4-EEG, with 1 kg and 3 kg force loads, the power of alpha band was significantly smaller than that from 0 kg for both non-fatigue and fatigue periods (all p  <  0.05). However, no significant difference of the power in alpha between 1 kg and 3 kg was observed (p  >  0.05 for all the force loads except C4-EEG with ELF simulation). The power of alpha band at fatigue status was significantly increased for both C3-EEG and C4-EEG when compared with the non-fatigue status (p  <  0.01 for all the force loads except 3 kg force from C4-EEG). With magnetic stimulation, the powers of alpha from C3-EEG and C4-EEG were significantly

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.

Opposite Effects of Capacity Load and Resolution Load on Distractor Processing

PubMed Central

Zhang, Weiwei; Luck, Steven J.

2014-01-01

According to the load theory of attention, an increased perceptual load reduces distractor processing whereas an increased working memory load facilitates distractor processing. Here we raise the possibility that the critical distinction may instead be between an emphasis on resolution and an emphasis on capacity. That is, perceptual load manipulations typically emphasize resolution (fine-grained discriminations), whereas working memory load manipulations typically emphasize capacity (simultaneous processing of multiple relevant stimuli). To test the plausibility of this hypothesis, we used a visual working memory task that emphasized either the number of items to be stored (capacity load, retaining two versus four colors) or the precision of the representations (resolution load, detecting small versus large color changes). We found that an increased capacity load led to increased flanker interference (a measure of distractor processing), whereas an increased resolution load led to reduced flanker interference. These opposite effects of capacity load and resolution load on distractor processing mirror the previously described opposite effects of perceptual load and working memory load. PMID:25365573

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).

Trunk coordination in healthy and chronic nonspecific low back pain subjects during repetitive flexion-extension tasks: Effects of movement asymmetry, velocity and load.

PubMed

Mokhtarinia, Hamid Reza; Sanjari, Mohammad Ali; Chehrehrazi, Mahshid; Kahrizi, Sedigheh; Parnianpour, Mohamad

2016-02-01

Multiple joint interactions are critical to produce stable coordinated movements and can be influenced by low back pain and task conditions. Inter-segmental coordination pattern and variability were assessed in subjects with and without chronic nonspecific low back pain (CNSLBP). Kinematic data were collected from 22 CNSLBP and 22 healthy volunteers during repeated trunk flexion-extension in various conditions of symmetry, velocity, and loading; each at two levels. Sagittal plane angular data were time normalized and used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify lumbar-pelvis and pelvis-thigh coordination patterns and variability. Statistical analysis revealed more in-phase coordination pattern in CNSLBP (p=0.005). There was less adaptation in the DP for the CNSLBP group, as shown by interactions of Group by Load (p=.008) and Group by Symmetry by Velocity (p=.03) for the DP of pelvis-thigh and lumbar-pelvis couplings, respectively. Asymmetric (p<0.001) and loaded (p=0.04) conditions caused less in-phase coordination. Coordination variability was higher during asymmetric and low velocity conditions (p<0.001). In conclusion, coordination pattern and variability could be influenced by trunk flexion-extension conditions. CNSLBP subjects demonstrated less adaptability of movement pattern to the demands of the flexion-extension task. Copyright © 2015 Elsevier B.V. All rights reserved.

Interactions Between Modality of Working Memory Load and Perceptual Load in Distractor Processing.

PubMed

Koshino, Hideya; Olid, Pilar

2015-01-01

The present study investigated interactions between working memory load and perceptual load. The load theory (Lavie, Hirst, de Fockert, & Viding, 2004 ) claims that perceptual load decreases distractor interference, whereas working memory load increases interference. However, recent studies showed that effects of working memory might depend on the relationship between modalities of working memory and task stimuli. Here, we examined whether the relationship between working memory load and perceptual load would remain the same across modalities. The results of Experiment 1 showed that verbal working memory load did not affect a compatibility effect for low perceptual load, whereas it increased the compatibility effect for high perceptual load. In Experiment 2, the compatibility effect remained the same regardless of visual working memory load. These results suggest that the effects of working memory load and perceptual load depend on the relationship between the modalities of working memory and stimuli.

Load Theory of Selective Attention and Cognitive Control

ERIC Educational Resources Information Center

Lavie, Nilli; Hirst, Aleksandra; de Fockert, Jan W.; Viding, Essi

2004-01-01

A load theory of attention in which distractor rejection depends on the level and type of load involved in current processing was tested. A series of experiments demonstrates that whereas high perceptual load reduces distractor interference, working memory load or dual-task coordination load increases distractor interference. These findings…

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.

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

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.

Task Descriptions in Diagnostic Radiology. Research Report No. 7. Volume 3, Machine-Related, Patient Care and Administrative Tasks: What Radiologists, Technologists, Nurses and Physicists Do to Run Things and Look After Patients and Equipment.

ERIC Educational Resources Information Center

Gilpatrick, Eleanor

The third of four volumes in Research Report No. 7 of the Health Services Mobility Study (HSMS), this book contains 149 diagnostic radiologist task descriptions that cover activities in the area of nursing (patient care), film processing, quality assurance, radiation protection, machine maintenance, housekeeping, and administration at the…

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.

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.

The effects of task difficulty and workload on training

NASA Technical Reports Server (NTRS)

Mane, Amir; Wickens, Christopher D.

1986-01-01

Four hypotheses regarding the possible effects of workload and task difficulty on training are proposed. These are: (1) increased levels of task difficulty will facilitate learning to the extent that these increases are (a) resource loading and (b) intrinsic to the component task to be learned; (2) decrease of task difficulty will facilitate learning to the extent that these decreases (a) reduce the resource load and (b) are extrinsic of the component task to be learned; (3) the lerner's tendency to conserve resources may bead to the adoption of undesirable, short-term, low resource strategies early in training; and (4) the effect of changes in resource demand on learning will depend upon the similarity of the resource whose demand is changed to the resource involved in learning.

Working memory costs of task switching.

PubMed

Liefooghe, Baptist; Barrouillet, Pierre; Vandierendonck, André; Camos, Valérie

2008-05-01

Although many accounts of task switching emphasize the importance of working memory as a substantial source of the switch cost, there is a lack of evidence demonstrating that task switching actually places additional demands on working memory. The present study addressed this issue by implementing task switching in continuous complex span tasks with strictly controlled time parameters. A series of 4 experiments demonstrate that recall performance decreased as a function of the number of task switches and that the concurrent load of item maintenance had no influence on task switching. These results indicate that task switching induces a cost on working memory functioning. Implications for theories of task switching, working memory, and resource sharing are addressed.

Effects of acute administration of nicotinic and muscarinic cholinergic agonists and antagonists on performance in different cost–benefit decision making tasks in rats

PubMed Central

Mendez, Ian A.; Gilbert, Ryan J.; Bizon, Jennifer L.

2012-01-01

Rationale Alterations in cost–benefit decision making accompany numerous neuropsychiatric conditions, including schizophrenia, attention deficit hyperactivity disorder, and addiction. Central cholinergic systems have been linked to the etiology and/or treatment of many of these conditions, but little is known about the role of cholinergic signaling in cost–benefit decision making. Objectives The goal of these experiments was to determine how cholinergic signaling is involved in cost–benefit decision making, using a behavioral pharmacological approach. Methods Male Long-Evans rats were trained in either “probability discounting” or “delay discounting” tasks, in which rats made discrete-trial choices between a small food reward and a large food reward associated with either varying probabilities of omission or varying delays to delivery, respectively. The effects of acute administration of different doses of nicotinic and muscarinic acetylcholine receptor agonists and antagonists were assessed in each task. Results In the probability discounting task, acute nicotine administration (1.0 mg/kg) significantly increased choice of the large risky reward, and control experiments suggested that this was due to robust nicotine-induced impairments in behavioral flexibility. In the delay discounting task, the muscarinic antagonists scopolamine (0.03, 0.1, and 0.3 mg/kg) and atropine (0.3 mg/kg) both significantly increased choice of the small immediate reward. Neither mecamylamine nor oxotremorine produced reliable effects on either of the decision making tasks. Conclusions These data suggest that cholinergic receptors play multiple roles in decision making contexts which include consideration of reward delay or probability. These roles should be considered when targeting these receptors for therapeutic purposes. PMID:22760484

The in vivo fate of nanoparticles and nanoparticle-loaded microcapsules after oral administration in mice: Evaluation of their potential for colon-specific delivery.

PubMed

Ma, Yiming; Fuchs, Adrian V; Boase, Nathan R B; Rolfe, Barbara E; Coombes, Allan G A; Thurecht, Kristofer J

2015-08-01

Anti-cancer drug loaded-nanoparticles (NPs) or encapsulation of NPs in colon-targeted delivery systems shows potential for increasing the local drug concentration in the colon leading to improved treatment of colorectal cancer. To investigate the potential of the NP-based strategies for colon-specific delivery, two formulations, free Eudragit® NPs and enteric-coated NP-loaded chitosan-hypromellose microcapsules (MCs) were fluorescently-labelled and their tissue distribution in mice after oral administration was monitored by multispectral small animal imaging. The free NPs showed a shorter transit time throughout the mouse digestive tract than the MCs, with extensive excretion of NPs in faeces at 5h. Conversely, the MCs showed complete NP release in the lower region of the mouse small intestine at 8h post-administration. Overall, the encapsulation of NPs in MCs resulted in a higher colonic NP intensity from 8h to 24h post-administration compared to the free NPs, due to a NP 'guarding' effect of MCs during their transit along mouse gastrointestinal tract which decreased NP excretion in faeces. These imaging data revealed that this widely-utilised colon-targeting MC formulation lacked site-precision for releasing its NP load in the colon, but the increased residence time of the NPs in the lower gastrointestinal tract suggests that it is still useful for localised release of chemotherapeutics, compared to NP administration alone. In addition, both formulations resided in the stomach of mice at considerable concentrations over 24h. Thus, adhesion of NP- or MC-based oral delivery systems to gastric mucosa may be problematic for colon-specific delivery of the cargo to the colon and should be carefully investigated for a full evaluation of particulate delivery systems. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

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

Results of the second Round Robin on opening-load measurement conducted by ASTM Task Group E24.04.04 on crack closure measurement and analysis

NASA Technical Reports Server (NTRS)

Phillips, E. P.

1993-01-01

A second experimental Round Robin on the measurement of the crack opening load in fatigue crack growth tests has been completed by the ASTM Task Group E24.04.04 on Crack Closure Measurement and Analysis. Fourteen laboratories participated in the testing of aluminum alloy compact tension specimens. Opening-load measurements were made at three crack lengths during constant Delta K, constant stress ratio tests by most of the participants. Four participants made opening-load measurements during threshold tests. All opening-load measurements were based on the analysis of specimens compliance behavior, where the displacement/strain was measured either at the crack mouth or the mid-height back face location. The Round Robin data were analyzed for opening load using two non-subjective analysis methods: the compliance offset and the correlation coefficient methods. The scatter in the opening load results was significantly reduced when some of the results were excluded from the analysis population based on an accept/reject criterion for raw data quality. The compliance offset and correlation coefficient opening load analysis methods produced similar results for data populations that had been screened to eliminate poor quality data.

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

Is Hand Selection Modulated by Cognitive-perceptual Load?

PubMed

Liang, Jiali; Wilkinson, Krista; Sainburg, Robert L

2018-01-15

Previous studies proposed that selecting which hand to use for a reaching task appears to be modulated by a factor described as "task difficulty". However, what features of a task might contribute to greater or lesser "difficulty" in the context of hand selection decisions has yet to be determined. There has been evidence that biomechanical and kinematic factors such as movement smoothness and work can predict patterns of selection across the workspace, suggesting a role of predictive cost analysis in hand-selection. We hypothesize that this type of prediction for hand-selection should recruit substantial cognitive resources and thus should be influenced by cognitive-perceptual loading. We test this hypothesis by assessing the role of cognitive-perceptual loading on hand selection decisions, using a visual search task that presents different levels of difficulty (cognitive-perceptual load), as established in previous studies on overall response time and efficiency of visual search. Although the data are necessarily preliminary due to small sample size, our data suggested an influence of cognitive-perceptual load on hand selection, such that the dominant hand was selected more frequently as cognitive load increased. Interestingly, cognitive-perceptual loading also increased cross-midline reaches with both hands. Because crossing midline is more costly in terms of kinematic and kinetic factors, our findings suggest that cognitive processes are normally engaged to avoid costly actions, and that the choice not-to-cross midline requires cognitive resources. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

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).

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...

Evaluating Maintenance Performance: Test Administrator's Manual and Test Subject's Instructions for Criterion Referenced Job Task Performance Tests for Electronic Maintenance. Final Report.

ERIC Educational Resources Information Center

Shriver, Edgar L.; And Others

This document furnishes a complete copy of the Test Subject's Instructions and the Test Administrator's Handbook for a battery of criterion referenced Job Task Performance Tests (JTPT) for electronic maintenance. General information is provided on soldering, Radar Set AN/APN-147(v), Radar Set Special Equipment, Radar Set Bench Test Set-Up, and…

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.

In Vivo Administration of a JAK3 Inhibitor during Acute SIV Infection Leads to Significant Increases in Viral Load during Chronic Infection

PubMed Central

Takahashi, Yoshiaki; Byrareddy, Siddappa N.; Albrecht, Christina; Brameier, Markus; Walter, Lutz; Mayne, Ann E.; Dunbar, Paul; Russo, Robert; Little, Dawn M.; Villinger, Tara; Khowawisetsut, Ladawan; Pattanapanyasat, Kovit; Villinger, Francois; Ansari, Aftab A.

2014-01-01

The studies reported herein are the first to document the effect of the in vivo administration of a JAK3 inhibitor for defining the potential role of NK cells during acute SIV infection of a group of 15 rhesus macaques (RM). An additional group of 16 MHC/KIR typed RM was included as controls. The previously optimized in vivo dose regimen (20 mg/kg daily for 35 days) led to a marked depletion of each of the major NK cell subsets both in the blood and gastro-intestinal tissues (GIT) during acute infection. While such depletion had no detectable effects on plasma viral loads during acute infection, there was a significant sustained increase in plasma viral loads during chronic infection. While the potential mechanisms that lead to such increased plasma viral loads during chronic infection remain unclear, several correlates were documented. Thus, during acute infection, the administration of the JAK3 inhibitor besides depleting all NK cell subsets also decreased some CD8+ T cells and inhibited the mobilization of the plasmacytoid dendritic cells in the blood and their localization to the GIT. Of interest is the finding that the administration of the JAK3 inhibitor during acute infection also resulted in the sustained maintenance during chronic infection of a high number of naïve and central memory CD4+ T cells, increases in B cells in the blood, but decreases in the frequencies and function of NKG2a+ NK cells within the GIT and blood, respectively. These data identify a unique role for JAK3 inhibitor sensitive cells, that includes NK cells during acute infection that in concert lead to high viral loads in SIV infected RM during chronic infection without affecting detectable changes in antiviral humoral/cellular responses. Identifying the precise mechanisms by which JAK3 sensitive cells exert their influence is critical with important implications for vaccine design against lentiviruses. PMID:24603870

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).

Local Dynamic Stability Associated with Load Carrying

PubMed Central

Lockhart, Thurmon E

2013-01-01

Objectives Load carrying tasks are recognized as one of the primary occupational factors leading to slip and fall injuries. Nevertheless, the mechanisms associated with load carrying and walking stability remain illusive. The objective of the current study was to apply local dynamic stability measure in walking while carrying a load, and to investigate the possible adaptive gait stability changes. Methods Current study involved 25 young adults in a biomechanics research laboratory. One tri-axial accelerometer was used to measure three-dimensional low back acceleration during continuous treadmill walking. Local dynamic stability was quantified by the maximum Lyapunov exponent (maxLE) from a nonlinear dynamics approach. Results Long term maxLE was found to be significant higher under load condition than no-load condition in all three reference axes, indicating the declined local dynamic stability associated with load carrying. Conclusion Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying. PMID:23515183

Quantifying performance and effects of load carriage during a challenging balancing task using an array of wireless inertial sensors.

PubMed

Cain, Stephen M; McGinnis, Ryan S; Davidson, Steven P; Vitali, Rachel V; Perkins, Noel C; McLean, Scott G

2016-01-01

We utilize an array of wireless inertial measurement units (IMUs) to measure the movements of subjects (n=30) traversing an outdoor balance beam (zigzag and sloping) as quickly as possible both with and without load (20.5kg). Our objectives are: (1) to use IMU array data to calculate metrics that quantify performance (speed and stability) and (2) to investigate the effects of load on performance. We hypothesize that added load significantly decreases subject speed yet results in increased stability of subject movements. We propose and evaluate five performance metrics: (1) time to cross beam (less time=more speed), (2) percentage of total time spent in double support (more double support time=more stable), (3) stride duration (longer stride duration=more stable), (4) ratio of sacrum M-L to A-P acceleration (lower ratio=less lateral balance corrections=more stable), and (5) M-L torso range of motion (smaller range of motion=less balance corrections=more stable). We find that the total time to cross the beam increases with load (t=4.85, p<0.001). Stability metrics also change significantly with load, all indicating increased stability. In particular, double support time increases (t=6.04, p<0.001), stride duration increases (t=3.436, p=0.002), the ratio of sacrum acceleration RMS decreases (t=-5.56, p<0.001), and the M-L torso lean range of motion decreases (t=-2.82, p=0.009). Overall, the IMU array successfully measures subject movement and gait parameters that reveal the trade-off between speed and stability in this highly dynamic balance task. Copyright © 2015 Elsevier B.V. All rights reserved.

75 FR 62611 - Interagency Task Force on Veterans Small Business Development

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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

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 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.

Man-machine Integration Design and Analysis System (MIDAS) Task Loading Model (TLM) experimental and software detailed design report

NASA Technical Reports Server (NTRS)

Staveland, Lowell

1994-01-01

This is the experimental and software detailed design report for the prototype task loading model (TLM) developed as part of the man-machine integration design and analysis system (MIDAS), as implemented and tested in phase 6 of the Army-NASA Aircrew/Aircraft Integration (A3I) Program. The A3I program is an exploratory development effort to advance the capabilities and use of computational representations of human performance and behavior in the design, synthesis, and analysis of manned systems. The MIDAS TLM computationally models the demands designs impose on operators to aide engineers in the conceptual design of aircraft crewstations. This report describes TLM and the results of a series of experiments which were run this phase to test its capabilities as a predictive task demand modeling tool. Specifically, it includes discussions of: the inputs and outputs of TLM, the theories underlying it, the results of the test experiments, the use of the TLM as both stand alone tool and part of a complete human operator simulation, and a brief introduction to the TLM software design.

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.

Chronic postnatal ornithine administration to rats provokes learning deficit in the open field task.

PubMed

Viegas, Carolina Maso; Busanello, Estela Natacha Brandt; Tonin, Anelise Miotti; Grings, Mateus; Moura, Alana Pimentel; Ritter, Luciana; Zanatta, Angela; Knebel, Lisiane Aurélio; Lobato, Vannessa Araujo; Pettenuzzo, Letícia Ferreira; Vargas, Carmen Regla; Leipnitz, Guilhian; Wajner, Moacir

2012-12-01

Hyperornithinemia is the biochemical hallmark of hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome, an inherited metabolic disease clinically characterized by mental retardation whose pathogenesis is still poorly known. In the present work, we produced a chemical animal model of hyperornithinemia induced by a subcutaneous injection of saline-buffered Orn (2-5 μmol/g body weight) to rats. High brain Orn concentrations were achieved, indicating that Orn is permeable to the blood brain barrier. We then investigated the effect of early chronic postnatal administration of Orn on physical development and on the performance of adult rats in the open field, the Morris water maze and in the step down inhibitory avoidance tasks. Chronic Orn treatment had no effect on the appearance of coat, eye opening or upper incisor eruption, nor on the free-fall righting reflex and on the adult rat performance in the Morris water maze and in the inhibitory avoidance tasks, suggesting that physical development, aversive and spatial localization were not changed by Orn. However, Orn-treated rats did not habituate to the open field apparatus, implying a deficit of learning/memory. Motor activity was the same for Orn- and saline- injected animals. We also verified that Orn subcutaneous injections provoked lipid peroxidation in the brain, as determined by a significant increase of thiobarbituric acid-reactive substances levels. Our results indicate that chronic early postnatal hyperornithinemia may impair the central nervous system, causing minor disabilities which result in specific learning deficiencies.

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

Blur Detection is Unaffected by Cognitive Load.

PubMed

Loschky, Lester C; Ringer, Ryan V; Johnson, Aaron P; Larson, Adam M; Neider, Mark; Kramer, Arthur F

2014-03-01

Blur detection is affected by retinal eccentricity, but is it also affected by attentional resources? Research showing effects of selective attention on acuity and contrast sensitivity suggests that allocating attention should increase blur detection. However, research showing that blur affects selection of saccade targets suggests that blur detection may be pre-attentive. To investigate this question, we carried out experiments in which viewers detected blur in real-world scenes under varying levels of cognitive load manipulated by the N -back task. We used adaptive threshold estimation to measure blur detection thresholds at 0°, 3°, 6°, and 9° eccentricity. Participants carried out blur detection as a single task, a single task with to-be-ignored letters, or an N-back task with four levels of cognitive load (0, 1, 2, or 3-back). In Experiment 1, blur was presented gaze-contingently for occasional single eye fixations while participants viewed scenes in preparation for an easy picture recognition memory task, and the N -back stimuli were presented auditorily. The results for three participants showed a large effect of retinal eccentricity on blur thresholds, significant effects of N -back level on N -back performance, scene recognition memory, and gaze dispersion, but no effect of N -back level on blur thresholds. In Experiment 2, we replicated Experiment 1 but presented the images tachistoscopically for 200 ms (half with, half without blur), to determine whether gaze-contingent blur presentation in Experiment 1 had produced attentional capture by blur onset during a fixation, thus eliminating any effect of cognitive load on blur detection. The results with three new participants replicated those of Experiment 1, indicating that the use of gaze-contingent blur presentation could not explain the lack of effect of cognitive load on blur detection. Thus, apparently blur detection in real-world scene images is unaffected by attentional resources, as

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.

14 CFR 27.341 - Gust loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Gust loads. 27.341 Section 27.341 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.341 Gust loads. The rotorcraft...

14 CFR 27.341 - Gust loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Gust loads. 27.341 Section 27.341 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.341 Gust loads. The rotorcraft...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

14 CFR 27.1589 - Loading information.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Loading information. 27.1589 Section 27.1589 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Manual and Approved Manual Material § 27.1589 Loading information. There must be loading instructions for...

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.

Comparative evaluation of workload estimation techniques in piloting tasks

NASA Technical Reports Server (NTRS)

Wierwille, W. W.

1983-01-01

Techniques to measure operator workload in a wide range of situations and tasks were examined. The sensitivity and intrusion of a wide variety of workload assessment techniques in simulated piloting tasks were investigated. Four different piloting tasks, psychomotor, perceptual, mediational, and communication aspects of piloting behavior were selected. Techniques to determine relative sensitivity and intrusion were applied. Sensitivity is the relative ability of a workload estimation technique to discriminate statistically significant differences in operator loading. High sensitivity requires discriminable changes in score means as a function of load level and low variation of the scores about the means. Intrusion is an undesirable change in the task for which workload is measured, resulting from the introduction of the workload estimation technique or apparatus.

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.

Do anticipatory postural adjustments occurring in different segments of the postural chain follow the same organisational rule for different task movement velocities, independently of the inertial load value?

PubMed

Bouisset, S; Richardson, J; Zattara, M

2000-05-01

Dynamic phenomena, termed anticipatory postural adjustments (APA), are known to precede the onset of voluntary movement. Their anticipatory nature confers a particular status on APAs: as they cannot be triggered reflexly by afferent signals induced by a voluntary movement, it can be asked whether the APA parameters are centrally programmed as a function of some task movement parameters or are only the peripheral consequence of control variables. To this end the present study aims to determine whether the APAs occurring at the different sites of the postural chain yield the same accelerometric patterns and follow the same organisational rules when the task movement velocity changes, independently of the inertial load value. Subjects performed unilateral shoulder flexions at maximal and submaximal velocities, with (IUF) and without (OUF) an additional inertial load. Accelerometers were attached to the wrist and trunk, and on both sides of the body at shank, thigh, hip and shoulder. The results show that: 1) there was evidence of anticipatory acceleration in all segments of the postural chain; 2) each acceleration profile for the anticipatory phase was maintained over different focal movement velocities whether there was an additional load or not; 3) there were significant linear relationships between the amplitude of each segmental anticipatory acceleration and the square of the task movement velocity, the slope of which differs as a function of the inertial load; 4) there were close intersegmental correlations between these anticipatory accelerations which did not depend on the inertial load. In addition the correlation between the lower limbs and the opposite side of the body was positive, suggesting a diagonal postural pattern. A comparison of the present kinematic data with the corresponding EMG data reported in the literature argues in favour of a centrally determined kinematic pattern. It is proposed that the diagonal postural pattern between postural segments

The duration perception of loading applications in smartphone: Effects of different loading types.

PubMed

Zhao, Wenguo; Ge, Yan; Qu, Weina; Zhang, Kan; Sun, Xianghong

2017-11-01

The loading time of a smartphone application is an important issue, which affects the satisfaction of phone users. This study evaluated the effects of black loading screen (BLS) and animation loading screen (ALS) during application loading on users' duration perception and satisfaction. A total of 43 volunteers were enrolled. They were asked to complete several tasks by clicking the icons of each application, such as camera or message. The duration of loading time for each application was manipulated. The participants were asked to estimate the duration, evaluate the loading speed and their satisfaction. The results showed that the estimated duration increased and the satisfaction for loading period declined along with the loading time increased. Compared with the BLS, the ALS prolonged the estimated duration, and lowered the evaluation of speed and satisfaction. We also discussed the tendency and key inflection points of the curves involving the estimated duration, speed evaluation and satisfaction with the loading time. Copyright © 2017 Elsevier Ltd. All rights reserved.

75 FR 62438 - Interagency Task Force on Veterans Small Business Development Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-08

... SMALL BUSINESS ADMINISTRATION Interagency Task Force on Veterans Small Business Development Meeting AGENCY: U.S. Small Business Administration. ACTION: Notice of open Federal Interagency Task Force... first public meeting of the Interagency Task Force on Veterans Small Business Development. The meeting...

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.

Administrator Training and Development: Conceptual Model.

ERIC Educational Resources Information Center

Boardman, Gerald R.

A conceptual model for an individualized training program for school administrators integrates processes, characteristics, and tasks through theory training and application. Based on an application of contingency theory, it provides a system matching up administrative candidates' needs in three areas (administrative process, administrative…

Identification of ergonomics interventions used to reduce musculoskeletal loading for building installation tasks.

PubMed

Albers, Jim; Estill, Cherie; MacDonald, Leslie

2005-07-01

Skilled workers in the mechanical and electrical installation (M/EI) building and construction trades experience high rates of disabling work-related musculoskeletal disorders (WMSDs). The M/EI trades involve installing piping; heating, ventilation and air conditioning (HVAC), and electrical systems in residential, commercial, and industrial buildings. In the absence of an ergonomics standard in the United States, some building and construction contractors, including M/EI sector contractors, have implemented various ergonomics interventions on their worksites on a voluntary basis. However, no data were available to determine the type of voluntary control measures being implemented, the task-specific hazards for which control measures needed to be developed or refined, and perceived barriers to improving hazard control. As part of a larger effort to obtain this data, the National Institute for Occupational Safety and Health (NIOSH) organized a stakeholder meeting to gather information regarding ergonomics interventions or "best practices" by M/EI contractors and tradespeople. The attendees included 39 industry representatives, 17 construction ergonomics researchers from government and academia, and four ergonomics consultants with experience in the construction industry. Participants spent more than 50% of time meeting in small trade-specific breakout sessions. According to the participants, tasks common to the three trades included (1) drill holes and shoot fasteners; (2) place and install systems, and (3) lift and carry materials and equipment. Engineering interventions described in the stakeholder meeting included tools, equipment, and engineered building materials; administrative controls largely consisted of training and education programs and modifications of work and management practice. Most participants believed that there were significant limits to the impact individual contractors and tradespeople could have in leading ergonomics improvement in the

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.

During computing tasks symptomatic female office workers demonstrate a trend towards higher cervical postural muscle load than asymptomatic office workers: an experimental study.

PubMed

Szeto, Grace P Y; Straker, Leon M; O'Sullivan, Peter B

2009-01-01

Do symptomatic female office workers perform computing tasks with higher cervical postural muscle loads (in terms of higher amplitudes and less muscular rest) and more discomfort compared with asymptomatic individuals? Are these differences in postural muscle loads consistent across bilateral (typing) and unilateral (mousing) conditions? an experimental case-control study. 18 symptomatic female office workers and 21 asymptomatic female office workers. Three conditions (typing, mousing, and type-and-mouse) were performed in random order. Muscle load was measured as median amplitude and gap frequency using surface EMG of bilateral cervical erector spinae and upper trapezius. Discomfort was measured using a numerical rating scale. The case group demonstrated 4.3% (95% CI 0.1 to 8.4) higher amplitude during typing and 3.5% (95% CI 0.1 to 6.9) higher amplitude during type-and-mouse in the right cervical erector spinae compared with the control group. There was a similar difference between groups in the left cervical erector spinae which also demonstrated a 1.2 gaps/min (95% CI -2.3 to 0.0) lower frequency during typing. The case group had significantly higher discomfort during all conditions compared with the control group. The case group demonstrated higher median amplitudes and lower gap frequencies than the control group during bilateral conditions (typing and type-and-mouse) compared with unilateral conditions (mousing) for both muscle groups. There was increased amplitude and decreased muscular rest in the cervical erector spinae of office workers performing typing and mousing tasks. These findings may represent a mechanism underlying computer-related musculoskeletal disorders.

Rules and more rules: the effects of multiple tasks, extensive training, and aging on task-switching performance.

PubMed

Buchler, Norbou G; Hoyer, William J; Cerella, John

2008-06-01

Task-switching performance was assessed in young and older adults as a function of the number of task sets to be actively maintained in memory (varied from 1 to 4) over the course of extended training (5 days). Each of the four tasks required the execution of a simple computational algorithm, which was instantaneously cued by the color of the two-digit stimulus. Tasks were presented in pure (task set size 1) and mixed blocks (task set sizes 2, 3, 4), and the task sequence was unpredictable. By considering task switching beyond two tasks, we found evidence for a cognitive control system that is not overwhelmed by task set size load manipulations. Extended training eliminated age effects in task-switching performance, even when the participants had to manage the execution of up to four tasks. The results are discussed in terms of current theories of cognitive control, including task set inertia and production system postulates.

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

Business Law: Task Analyses. Competency-Based Education.

ERIC Educational Resources Information Center

Henrico County Public Schools, Glen Allen, VA. Virginia Vocational Curriculum Center.

This task analysis guide is intended to help teachers and administrators develop instructional materials and implement competency-based education for a course in business law. Section 1 contains a validated task inventory for business law. For each task, applicable information pertaining to performance and enabling objectives, criterion-referenced…

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.

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

How do task characteristics affect learning and performance? The roles of variably mapped and dynamic tasks.

PubMed

Macnamara, Brooke N; Frank, David J

2018-05-01

For well over a century, scientists have investigated individual differences in performance. The majority of studies have focused on either differences in practice, or differences in cognitive resources. However, the predictive ability of either practice or cognitive resources varies considerably across tasks. We are the first to examine task characteristics' impact on learning and performance in a complex task while controlling for other task characteristics. In 2 experiments we test key theoretical task characteristic thought to moderate the relationship between practice, cognitive resources, and performance. We devised a task where each of several key task characteristics can be manipulated independently. Participants played 5 rounds of a game similar to the popular tower defense videogame Plants vs. Zombies where both cognitive load and game characteristics were manipulated. In Experiment 1, participants either played a consistently mapped version-the stimuli and the associated meaning of their properties were constant across the 5 rounds-or played a variably mapped version-the stimuli and the associated meaning of their properties changed every few minutes. In Experiment 2, participants either played a static version-that is, turn taking with no time pressure-or played a dynamic version-that is, the stimuli moved regardless of participants' response rates. In Experiment 1, participants' accuracy and efficiency were substantially hindered in the variably mapped conditions. In Experiment 2, learning and performance accuracy were hindered in the dynamic conditions, especially when under cognitive load. Our results suggest that task characteristics impact the relative importance of cognitive resources and practice on predicting learning and performance. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Co-administration with cell penetrating peptide enhances the oral bioavailability of docetaxel-loaded nanoparticles.

PubMed

Bu, Xiangyuan; Zhu, Tao; Ma, Yiran; Shen, Qi

2015-05-01

This study proposes a novel docetaxel (DTX) cyclodextrin inclusion-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles (D-CNPs) system with cell penetrating peptide (CPP), and evaluates its potential for oral administration of DTX. Heptaarginine (R7) was used as the CPP. D-CNPs were prepared by the double-emulsification method. The mean particle size and zeta potential of the resulting D-CNPs were 198.7 ± 12.56 nm and -27.25 ± 4.62 mV, respectively, and their mean encapsulation efficiency and drug loading were 80.35 ± 6.37% and 1.02 ± 0.15%, respectively. The morphology of the D-CNPs was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). The release behavior of the D-CNPs was studied by using the dialysis method. The relative bioavailability of D-CNPs and D-CNPs co-administered with R7 was enhanced about 5.57- and 9.43-fold, respectively, compared with the free DTX suspension. Furthermore, D-CNPs with R7 displayed maximum cytotoxicity against MCF-7 cells in MTT assay. D-CNPs co-administered with R7 showed markedly higher fluorescence intensity than D-CNPs without CPP. The results suggest that the D-CNPs co-administered with R7 could be a potential delivery system with excellent therapeutic efficacy for targeting the drugs to cancer cells.

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.

Distributed and cooperative task processing: Cournot oligopolies on a graph.

PubMed

Pavlic, Theodore P; Passino, Kevin M

2014-06-01

This paper introduces a novel framework for the design of distributed agents that must complete externally generated tasks but also can volunteer to process tasks encountered by other agents. To reduce the computational and communication burden of coordination between agents to perfectly balance load around the network, the agents adjust their volunteering propensity asynchronously within a fictitious trading economy. This economy provides incentives for nontrivial levels of volunteering for remote tasks, and thus load is shared. Moreover, the combined effects of diminishing marginal returns and network topology lead to competitive equilibria that have task reallocations that are qualitatively similar to what is expected in a load-balancing system with explicit coordination between nodes. In the paper, topological and algorithmic conditions are given that ensure the existence and uniqueness of a competitive equilibrium. Additionally, a decentralized distributed gradient-ascent algorithm is given that is guaranteed to converge to this equilibrium while not causing any node to over-volunteer beyond its maximum task-processing rate. The framework is applied to an autonomous-air-vehicle example, and connections are drawn to classic studies of the evolution of cooperation in nature.

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.

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.

Teachers' Aides: Tasks and Concerns

ERIC Educational Resources Information Center

Balderson, James H.; Nixon, Mary

1976-01-01

Addresses three questions: (1) What tasks do aides perform? (2) Does training make a difference in the type of tasks aides perform? (3) What are the concerns of aides? (Available from the Department of Educational Administration, The University of Alberta, Edmonton, Alberta, Canada T6G 2G5; $0.50, single copy.) (Author/IRT)

Face and object encoding under perceptual load: ERP evidence.

PubMed

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

2011-02-14

According to the perceptual load theory, processing of a task-irrelevant distractor is abolished when attentional resources are fully consumed by task-relevant material. As an exception, however, famous faces have been shown to elicit repetition modulations in event-related potentials - an N250r - despite high load at initial presentation, suggesting preserved face-encoding. Here, we recorded N250r repetition modulations by unfamiliar faces, hands, and houses, and tested face specificity of preserved encoding under high load. In an immediate (S1-S2) repetition priming paradigm, participants performed a letter identification task on S1 by indicating whether an "X" vs. "N" was among 6 different (high load condition) or 6 identical (low load condition) letters. Letter strings were superimposed on distractor faces, hands, or houses. Subsequent S2 probes were either identical repetitions of S1 distractors, non-repeated exemplars from the same category, or infrequent butterflies, to which participants responded. Independent of attentional load at S1, an occipito-temporal N250r was found for unfamiliar faces. In contrast, no repetition-related neural modulation emerged for houses or hands. This strongly suggests that a putative face-selective attention module supports encoding under high load, and that similar mechanisms are unavailable for other natural or artificial objects. Copyright © 2010 Elsevier Inc. All rights reserved.

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 25.301 - Loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loads. 25.301 Section 25.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... equilibrium with inertia forces, considering each item of mass in the airplane. These loads must be...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 29.301 - Loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Loads. 29.301 Section 29.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

14 CFR 27.301 - Loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loads. 27.301 Section 27.301 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads...

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

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.

Neural effects of cognitive control load on auditory selective attention.

PubMed

Sabri, Merav; Humphries, Colin; Verber, Matthew; Liebenthal, Einat; Binder, Jeffrey R; Mangalathu, Jain; Desai, Anjali

2014-08-01

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 130-210ms, 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

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

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.

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.

14 CFR 31.21 - Loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loads. 31.21 Section 31.21 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.21 Loads. Strength requirements are specified in terms of...

14 CFR 31.21 - Loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loads. 31.21 Section 31.21 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.21 Loads. Strength requirements are specified in terms of...

Evaluation in vitro and in vivo of curcumin-loaded mPEG-PLA/TPGS mixed micelles for oral administration.

PubMed

Duan, Yuwei; Zhang, Baomei; Chu, Lianjun; Tong, Henry Hy; Liu, Weidong; Zhai, Guangxi

2016-05-01

The aim of this work is to prepare and characterize curcumin-loaded methoxy poly(ethylene glycol)-poly(lactide) (mPEG-PLA)/D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) mixed micelles (CUR-MPP-TPGS-MMs), analyze the influence of formulation on enhancing the solubility of curcumin in water, and evaluate the improvement of intestinal absorption after oral administration. CUR-MPP-TPGS-MMs were prepared using the thin film diffusion method and optimized with the uniform design. The optimal CUR-MPP-TPGS-MMs were provided with high drug-loading (16.1%), small size (46.0 nm) and spherical shape. Low critical micelle concentration (CMC) and superior dilution stability showed that CUR-MPP-TPGS-MMs could keep integrity during the dilution of gastrointestinal fluid. In vitro drug release study indicated a sustained release of curcumin from CUR-MPP-TPGS-MMs in simulated gastrointestinal solution. The absorption mechanism of passive diffusion was obtained by measuring in situ intestinal absorption of CUR-MPP-TPGS-MMs in rats, and the best absorption segment was found to be the duodenum. The pharmacokinetics was evaluated in rats at the dose of 75 mg/kg by intragastric administration. The Cmax and mean retention time (MRT0-24) for CUR-MPP-TPGS-MMs were both increased, and the relative bioavailability of micelle formulation to curcumin suspension was 927.3%. These results suggested that mPEG-PLA/TPGS mixed micelle system (MPP-TPGS-MMs) showed great potential in improving oral bioavailability of curcumin. Copyright © 2016 Elsevier B.V. All rights reserved.

Natural Resources Management: Task Analyses. Competency-Based Education.

ERIC Educational Resources Information Center

James Madison Univ., Harrisonburg, VA.

This task analysis guide is intended to help teachers and administrators develop instructional materials and implement competency-based education for natural resources management courses in the agricultural resources program. Section 1 contains a validated task inventory for natural resources management. For each task, applicable information…

77 FR 10797 - Aviation Rulemaking Advisory Committee-New Task

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-23

... Committee--New Task AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of withdrawal of task assignment for the Aviation Rulemaking Advisory Committee (ARAC). SUMMARY: The FAA has withdrawn a task... is to inform the public of the FAA's decision to withdraw this task. FOR FURTHER INFORMATION CONTACT...

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.

Mobile Thread Task Manager

NASA Technical Reports Server (NTRS)

Clement, Bradley J.; Estlin, Tara A.; Bornstein, Benjamin J.

2013-01-01

The Mobile Thread Task Manager (MTTM) is being applied to parallelizing existing flight software to understand the benefits and to develop new techniques and architectural concepts for adapting software to multicore architectures. It allocates and load-balances tasks for a group of threads that migrate across processors to improve cache performance. In order to balance-load across threads, the MTTM augments a basic map-reduce strategy to draw jobs from a global queue. In a multicore processor, memory may be "homed" to the cache of a specific processor and must be accessed from that processor. The MTTB architecture wraps access to data with thread management to move threads to the home processor for that data so that the computation follows the data in an attempt to avoid L2 cache misses. Cache homing is also handled by a memory manager that translates identifiers to processor IDs where the data will be homed (according to rules defined by the user). The user can also specify the number of threads and processors separately, which is important for tuning performance for different patterns of computation and memory access. MTTM efficiently processes tasks in parallel on a multiprocessor computer. It also provides an interface to make it easier to adapt existing software to a multiprocessor environment.

Increased Early Processing of Task-Irrelevant Auditory Stimuli in Older Adults

PubMed Central

Tusch, Erich S.; Alperin, Brittany R.; Holcomb, Phillip J.; Daffner, Kirk R.

2016-01-01

The inhibitory deficit hypothesis of cognitive aging posits that older adults’ inability to adequately suppress processing of irrelevant information is a major source of cognitive decline. Prior research has demonstrated that in response to task-irrelevant auditory stimuli there is an age-associated increase in the amplitude of the N1 wave, an ERP marker of early perceptual processing. Here, we tested predictions derived from the inhibitory deficit hypothesis that the age-related increase in N1 would be 1) observed under an auditory-ignore, but not auditory-attend condition, 2) attenuated in individuals with high executive capacity (EC), and 3) augmented by increasing cognitive load of the primary visual task. ERPs were measured in 114 well-matched young, middle-aged, young-old, and old-old adults, designated as having high or average EC based on neuropsychological testing. Under the auditory-ignore (visual-attend) task, participants ignored auditory stimuli and responded to rare target letters under low and high load. Under the auditory-attend task, participants ignored visual stimuli and responded to rare target tones. Results confirmed an age-associated increase in N1 amplitude to auditory stimuli under the auditory-ignore but not auditory-attend task. Contrary to predictions, EC did not modulate the N1 response. The load effect was the opposite of expectation: the N1 to task-irrelevant auditory events was smaller under high load. Finally, older adults did not simply fail to suppress the N1 to auditory stimuli in the task-irrelevant modality; they generated a larger response than to identical stimuli in the task-relevant modality. In summary, several of the study’s findings do not fit the inhibitory-deficit hypothesis of cognitive aging, which may need to be refined or supplemented by alternative accounts. PMID:27806081

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.

Changes in intervertebral disk dimensions after a loading task and the relationship with stature change measurements.

PubMed

Lewis, Sandra E; Fowler, Neil E

2009-10-01

Lewis SE, Fowler NE. Changes in intervertebral disk dimensions after a loading task and the relationship with stature change measurements. To test the hypothesis that there would be a linear relationship between overall stature change determined by stadiometry and markers of lumbar disk height loss determined from magnetic resonance imaging (MRI). The short-term loading response of the lumbar spine was evaluated with both stadiometry and MRI, using a within-subject repeated-measures design. Measures were obtained both before and after 15 minutes of walking wearing a weighted vest (20% of body mass). Stature loss measured on the stadiometer was compared with change in lumbar spine length assessed from the MRI images. A university laboratory. Participants (N=13; mean age +/- SD, 28.5+/-5.2y; mean height +/- SD, 1.76+/-0.10m; mean body mass +/- SD, 76.6+/-14.9kg) were invited to take part in the investigation. The group was mixed (9 men, 4 women) and comprised people with no history of low back pain. Not applicable. Lumbar spine length assessed via MRI and stature change measured via stadiometry. A significant height loss was observed over the complete lumbar spine (P<.05), and a significant correlation was found between the decrease in posterior spine length and stature loss (r=.61). The results were supportive of the use of stadiometry as an indirect measure of changes in intervertebral disk height.

Extrinsic cognitive load impairs low-level speech perception.

PubMed

Mattys, Sven L; Barden, Katharine; Samuel, Arthur G

2014-06-01

Recent research has suggested that the extrinsic cognitive load generated by performing a nonlinguistic visual task while perceiving speech increases listeners' reliance on lexical knowledge and decreases their capacity to perceive phonetic detail. In the present study, we asked whether this effect is accounted for better at a lexical or a sublexical level. The former would imply that cognitive load directly affects lexical activation but not perceptual sensitivity; the latter would imply that increased lexical reliance under cognitive load is only a secondary consequence of imprecise or incomplete phonetic encoding. Using the phoneme restoration paradigm, we showed that perceptual sensitivity decreases (i.e., phoneme restoration increases) almost linearly with the effort involved in the concurrent visual task. However, cognitive load had only a minimal effect on the contribution of lexical information to phoneme restoration. We concluded that the locus of extrinsic cognitive load on the speech system is perceptual rather than lexical. Mechanisms by which cognitive load increases tolerance to acoustic imprecision and broadens phonemic categories were discussed.

[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.

Cognitive load disrupts implicit theory-of-mind processing.

PubMed

Schneider, Dana; Lam, Rebecca; Bayliss, Andrew P; Dux, Paul E

2012-08-01

Eye movements in Sally-Anne false-belief tasks appear to reflect the ability to implicitly monitor the mental states of other individuals (theory of mind, or ToM). It has recently been proposed that an early-developing, efficient, and automatically operating ToM system subserves this ability. Surprisingly absent from the literature, however, is an empirical test of the influence of domain-general executive processing resources on this implicit ToM system. In the study reported here, a dual-task method was employed to investigate the impact of executive load on eye movements in an implicit Sally-Anne false-belief task. Under no-load conditions, adult participants displayed eye movement behavior consistent with implicit belief processing, whereas evidence for belief processing was absent for participants under cognitive load. These findings indicate that the cognitive system responsible for implicitly tracking beliefs draws at least minimally on executive processing resources. Thus, even the most low-level processing of beliefs appears to reflect a capacity-limited operation.

The impact of secondary-task type on the sensitivity of reaction-time based measurement of cognitive load for novices learning surgical skills using simulation.

PubMed

Rojas, David; Haji, Faizal; Shewaga, Rob; Kapralos, Bill; Dubrowski, Adam

2014-01-01

Interest in the measurement of cognitive load (CL) in simulation-based education has grown in recent years. In this paper we present two pilot experiments comparing the sensitivity of two reaction time based secondary task measures of CL. The results suggest that simple reaction time measures are sensitive enough to detect changes in CL experienced by novice learners in the initial stages of simulation-based surgical skills training.

Business and Marketing Cluster. Task Analyses.

ERIC Educational Resources Information Center

Henrico County Public Schools, Glen Allen, VA. Virginia Vocational Curriculum and Resource Center.

Developed in Virginia, this publication contains task analysis guides to support selected tech prep programs that prepare students for careers in the business and marketing cluster. Guides are included for accounting systems, legal systems administration, office systems technology, and retail marketing. Each task analyses guide has the following…

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.

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

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.

Low cognitive load strengthens distractor interference while high load attenuates when cognitive load and distractor possess similar visual characteristics.

PubMed

Minamoto, Takehiro; Shipstead, Zach; Osaka, Naoyuki; Engle, Randall W

2015-07-01

Studies on visual cognitive load have reported inconsistent effects of distractor interference when distractors have visual characteristic that are similar to the cognitive load. Some studies have shown that the cognitive load enhances distractor interference, while others reported an attenuating effect. We attribute these inconsistencies to the amount of cognitive load that a person is required to maintain. Lower amounts of cognitive load increase distractor interference by orienting attention toward visually similar distractors. Higher amounts of cognitive load attenuate distractor interference by depleting attentional resources needed to process distractors. In the present study, cognitive load consisted of faces (Experiments 1-3) or scenes (Experiment 2). Participants performed a selective attention task in which they ignored face distractors while judging a color of a target dot presented nearby, under differing amounts of load. Across these experiments distractor interference was greater in the low-load condition and smaller in the high-load condition when the content of the cognitive load had similar visual characteristic to the distractors. We also found that when a series of judgments needed to be made, the effect was apparent for the first trial but not for the second. We further tested an involvement of working memory capacity (WMC) in the load effect (Experiment 3). Interestingly, both high and low WMC groups received an equivalent effect of the cognitive load in the first distractor, suggesting these effects are fairly automatic.

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.

30 CFR 56.6307 - Drill stem loading.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Drill stem loading. 56.6307 Section 56.6307 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Drill stem loading. Explosive material shall not be loaded into blastholes with drill stem equipment or...

30 CFR 56.6307 - Drill stem loading.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Drill stem loading. 56.6307 Section 56.6307 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Drill stem loading. Explosive material shall not be loaded into blastholes with drill stem equipment or...

30 CFR 56.6307 - Drill stem loading.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Drill stem loading. 56.6307 Section 56.6307 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Drill stem loading. Explosive material shall not be loaded into blastholes with drill stem equipment or...

30 CFR 56.6307 - Drill stem loading.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Drill stem loading. 56.6307 Section 56.6307 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Drill stem loading. Explosive material shall not be loaded into blastholes with drill stem equipment or...

30 CFR 56.6307 - Drill stem loading.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Drill stem loading. 56.6307 Section 56.6307 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Drill stem loading. Explosive material shall not be loaded into blastholes with drill stem equipment or...

Simulation of short-term electric load using an artificial neural network

NASA Astrophysics Data System (ADS)

Ivanin, O. A.

2018-01-01

While solving the task of optimizing operation modes and equipment composition of small energy complexes or other tasks connected with energy planning, it is necessary to have data on energy loads of a consumer. Usually, there is a problem with obtaining real load charts and detailed information about the consumer, because a method of load-charts simulation on the basis of minimal information should be developed. The analysis of work devoted to short-term loads prediction allows choosing artificial neural networks as a most suitable mathematical instrument for solving this problem. The article provides an overview of applied short-term load simulation methods; it describes the advantages of artificial neural networks and offers a neural network structure for electric loads of residential buildings simulation. The results of modeling loads with proposed method and the estimation of its error are presented.

Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions.

PubMed

Murphy, Gillian; Greene, Ciara M

2016-01-01

Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals.

Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions

PubMed Central

Murphy, Gillian; Greene, Ciara M.

2016-01-01

Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals. PMID:27625628

Cerebellar tDCS does not affect performance in the N-back task.

PubMed

van Wessel, Brenda W V; Claire Verhage, M; Holland, Peter; Frens, Maarten A; van der Geest, Jos N

2016-01-01

The N-back task is widely used in cognitive research. Furthermore, the cerebellum's role in cognitive processes is becoming more widely recognized. Studies using transcranial direct current stimulation (tDCS) have demonstrated effects of cerebellar stimulation on several cognitive tasks. Therefore, the aim of this study was to investigate the effects of cerebellar tDCS on cognitive performance by using the N-back task. The cerebellum of 12 participants was stimulated during the task. Moreover, the cognitive load was manipulated in N = 2, N = 3, and N = 4. Every participant received three tDCS conditions (anodal, cathodal, and sham) divided over three separated days. It was expected that anodal stimulation would improve performance on the task. Each participant performed 6 repetitions of every load in which correct responses, false alarms, and reaction times were recorded. We found significant differences between the three levels of load in the rate of correct responses and false alarms, indicating that subjects followed the expected pattern of performance for the N-back task. However, no significant differences between the three tDCS conditions were found. Therefore, it was concluded that in this study cognitive performance on the N-back task was not readily influenced by cerebellar tDCS, and any true effects are likely to be small. We discuss several limitations in task design and suggest future experiments to address such issues.

Defining Administrative Tasks, Evaluating Performance, and Developing Skills.

ERIC Educational Resources Information Center

Herman, Janice L.; Herman, Jerry J.

1995-01-01

To ensure high performance, administrators should develop an articulated structure and process systems approach that identifies the critical success factors (CSFs) of performance for each position; appropriate indicators and scales; and a personal-improvement plan based on last year's evaluation. Once CSFs are identified and written into the…

Analysis of Skeletal Muscle Metrics as Predictors of Functional Task Performance

NASA Technical Reports Server (NTRS)

Ryder, Jeffrey W.; Buxton, Roxanne E.; Redd, Elizabeth; Scott-Pandorf, Melissa; Hackney, Kyle J.; Fiedler, James; Ploutz-Snyder, Robert J.; Bloomberg, Jacob J.; Ploutz-Snyder, Lori L.

2010-01-01

PURPOSE: The ability to predict task performance using physiological performance metrics is vital to ensure that astronauts can execute their jobs safely and effectively. This investigation used a weighted suit to evaluate task performance at various ratios of strength, power, and endurance to body weight. METHODS: Twenty subjects completed muscle performance tests and functional tasks representative of those that would be required of astronauts during planetary exploration (see table for specific tests/tasks). Subjects performed functional tasks while wearing a weighted suit with additional loads ranging from 0-120% of initial body weight. Performance metrics were time to completion for all tasks except hatch opening, which consisted of total work. Task performance metrics were plotted against muscle metrics normalized to "body weight" (subject weight + external load; BW) for each trial. Fractional polynomial regression was used to model the relationship between muscle and task performance. CONCLUSION: LPMIF/BW is the best predictor of performance for predominantly lower-body tasks that are ambulatory and of short duration. LPMIF/BW is a very practical predictor of occupational task performance as it is quick and relatively safe to perform. Accordingly, bench press work best predicts hatch-opening work performance.

14 CFR 27.865 - External loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... must be shown by analysis, test, or both, that the rotorcraft external load attaching means for rotorcraft-load combinations to be used for nonhuman external cargo applications can withstand a limit static...

14 CFR 27.865 - External loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... must be shown by analysis, test, or both, that the rotorcraft external load attaching means for rotorcraft-load combinations to be used for nonhuman external cargo applications can withstand a limit static...

14 CFR 27.865 - External loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... must be shown by analysis, test, or both, that the rotorcraft external load attaching means for rotorcraft-load combinations to be used for nonhuman external cargo applications can withstand a limit static...

14 CFR 27.865 - External loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... must be shown by analysis, test, or both, that the rotorcraft external load attaching means for rotorcraft-load combinations to be used for nonhuman external cargo applications can withstand a limit static...

14 CFR 27.865 - External loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... must be shown by analysis, test, or both, that the rotorcraft external load attaching means for rotorcraft-load combinations to be used for nonhuman external cargo applications can withstand a limit static...

Following ergonomics guidelines decreases physical and cardiovascular workload during cleaning tasks.

PubMed

Samani, Afshin; Holtermann, Andreas; Søgaard, Karen; Holtermann, Andreas; Madeleine, Pascal

2012-01-01

The aim was to investigate the effect of ergonomics guidelines on muscular activity, postural and cardiovascular load during cleaning. Eighteen cleaners performed 10 min of cleaning tasks in two locations; three min in a laboratory and seven min in a lecture room. All participants performed the task with or without focusing on ergonomics guidelines (ergonomics/non-ergonomics session). Bipolar surface electromyography was recorded bilaterally from upper trapezius and erector spinae muscles. A tri-axial accelerometer package was mounted on the low back (L5-S1) to measure postural changes, and the cardiovascular load was estimated by electrocardiogram. Ergonomics sessions resulted in lower muscular load, a more complex pattern of muscular activity, lower range of motion and angular velocity of the trunk as well as lower cardiovascular load compared with non-ergonomics sessions (p < 0.05). The study highlighted the multiple musculoskeletal and cardiovascular benefits of following ergonomics guidelines during cleaning tasks. This study investigated the effects of following instructive ergonomics guidelines during cleaning tasks (daily curriculum of cleaning including mopping, sweeping, changing trash bins and cleaning of desks and blackboards). Following the ergonomics guidelines reduces the general workload and induces a more complex pattern of muscular activity. The study contributes with novel knowledge concerning ergonomics guidelines and work techniques.

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.

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'…

The Effect of Physical Load and Environment on Soldier Performance

DTIC Science & Technology

2014-02-01

when walking over obstacles compared with standing still with and without a load. Knapik et al. (1990) found significant decrements in military...load carriage (34–61 kg carried 20 km) led to decrements in subsequent physical performance but not in cognitive ability. Crowell et al. (1999) found...with a simultaneous visual navigation task was thought to be advantageous; Wickens’s (1984) multiple resource theory stated that different tasks can

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

Biomechanical analysis of loading/unloading a ladder on a truck.

PubMed

Moriguchi, Cristiane Shinohara; Carnaz, Leticia; de Miranda, Luiz Carlos; Marklin, Richard William; Coury, Helenice Jane Cote Gil

2012-01-01

Loading/unloading a ladder on vehicles are frequent tasks and involve overhead handling that may expose workers to risk factors of shoulder musculoskeletal disorders. The objective of the present study was to evaluate posture, forces required and perceived exertion when loading and unloading the ladder on a utility truck. Thirteen male overhead line workers from an electric utility in Brazil participated in this study. Shoulder elevation angle was measured using inclinometers. The required force to load/unload the ladder was measured by dynamometer. Subjective assessment of the perceived exertion was recorded to compare the exertion reported during the test conditions to the field conditions. The task of loading/unloading the ladder presented risks of shoulder musculoskeletal disorders (MSDs) to workers because it requires high levels of force (approximately 60% of the maximal force) combined with overhead posture of the shoulders (more than 100° from the neutral posture). Age and height presented to interfere in biomechanical risks presented in load/unload task. There was no significant difference between the subjective exertion during the test conditions and handling the ladder in the field. Ergonomic intervention is recommended to reduce these risks for shoulder MSDs.

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…

Effects of Cognitive Load on Driving Performance: The Cognitive Control Hypothesis.

PubMed

Engström, Johan; Markkula, Gustav; Victor, Trent; Merat, Natasha

2017-08-01

The objective of this paper was to outline an explanatory framework for understanding effects of cognitive load on driving performance and to review the existing experimental literature in the light of this framework. Although there is general consensus that taking the eyes off the forward roadway significantly impairs most aspects of driving, the effects of primarily cognitively loading tasks on driving performance are not well understood. Based on existing models of driver attention, an explanatory framework was outlined. This framework can be summarized in terms of the cognitive control hypothesis: Cognitive load selectively impairs driving subtasks that rely on cognitive control but leaves automatic performance unaffected. An extensive literature review was conducted wherein existing results were reinterpreted based on the proposed framework. It was demonstrated that the general pattern of experimental results reported in the literature aligns well with the cognitive control hypothesis and that several apparent discrepancies between studies can be reconciled based on the proposed framework. More specifically, performance on nonpracticed or inherently variable tasks, relying on cognitive control, is consistently impaired by cognitive load, whereas the performance on automatized (well-practiced and consistently mapped) tasks is unaffected and sometimes even improved. Effects of cognitive load on driving are strongly selective and task dependent. The present results have important implications for the generalization of results obtained from experimental studies to real-world driving. The proposed framework can also serve to guide future research on the potential causal role of cognitive load in real-world crashes.

Barriers to critical thinking: workflow interruptions and task switching among nurses.

PubMed

Cornell, Paul; Riordan, Monica; Townsend-Gervis, Mary; Mobley, Robin

2011-10-01

Nurses are increasingly called upon to engage in critical thinking. However, current workflow inhibits this goal with frequent task switching and unpredictable demands. To assess workflow's cognitive impact, nurses were observed at 2 hospitals with different patient loads and acuity levels. Workflow on a medical/surgical and pediatric oncology unit was observed, recording tasks, tools, collaborators, and locations. Nineteen nurses were observed for a total of 85.2 hours. Tasks were short with a mean duration of 62.4 and 81.6 seconds on the 2 units. More than 50% of the recorded tasks were less than 30 seconds in length. An analysis of task sequence revealed few patterns and little pairwise repetition. Performance on specific tasks differed between the 2 units, but the character of the workflow was highly similar. The nonrepetitive flow and high amount of switching indicate nurses experience a heavy cognitive load with little uninterrupted time. This implies that nurses rarely have the conditions necessary for critical thinking.

14 CFR 29.865 - External loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) It must be shown by analysis, test, or both, that the rotorcraft external load attaching means for rotorcraft-load combinations to be used for nonhuman external cargo applications can withstand a limit static...