Revisiting the Development of Time Sharing Using a Dual Motor Task Performance

ERIC Educational Resources Information Center

Getchell, Nancy; Pabreja, Priya

2006-01-01

In this article, the authors discuss and examine how to develop time sharing using a dual motor task and its effects. They state that when one is required to perform two tasks at the same time (time sharing), an individual may experience difficulty in expressing one or both of the tasks. This phenomenon, known as interference, has been studied…

Time response for sensor sensed to actuator response for mobile robotic system

NASA Astrophysics Data System (ADS)

Amir, N. S.; Shafie, A. A.

2017-11-01

Time and performance of a mobile robot are very important in completing the tasks given to achieve its ultimate goal. Tasks may need to be done within a time constraint to ensure smooth operation of a mobile robot and can result in better performance. The main purpose of this research was to improve the performance of a mobile robot so that it can complete the tasks given within time constraint. The problem that is needed to be solved is to minimize the time interval between sensor detection and actuator response. The research objective is to analyse the real time operating system performance of sensors and actuators on one microcontroller and on two microcontroller for a mobile robot. The task for a mobile robot for this research is line following with an obstacle avoidance. Three runs will be carried out for the task and the time between the sensors senses to the actuator responses were recorded. Overall, the results show that two microcontroller system have better response time compared to the one microcontroller system. For this research, the average difference of response time is very important to improve the internal performance between the occurrence of a task, sensors detection, decision making and actuator response of a mobile robot. This research helped to develop a mobile robot with a better performance and can complete task within the time constraint.

Feedback and the rationing of time and effort among competing tasks.

PubMed

Northcraft, Gregory B; Schmidt, Aaron M; Ashford, Susan J

2011-09-01

The study described here tested a model of how characteristics of the feedback environment influence the allocation of resources (time and effort) among competing tasks. Results demonstrated that performers invest more resources on tasks for which higher quality (more timely and more specific) feedback is available; this effect was partially mediated by task salience and task expectancies. Feedback timing and feedback specificity demonstrated both main and interaction effects on resource allocations. Results also demonstrated that performers do better on tasks for which higher quality feedback is available; this effect was mediated by resources allocated to tasks. The practical and theoretical implications of the role of the feedback environment in managing performance are discussed. PsycINFO Database Record (c) 2011 APA, all rights reserved

Remember to do: insomnia versus control groups in a prospective memory task.

PubMed

Fabbri, Marco; Tonetti, Lorenzo; Martoni, Monica; Natale, Vincenzo

2015-01-01

Primary insomnia is characterized by difficulty in falling asleep and/or remaining asleep, by early morning awakening and/or nonrestorative sleep, and resultant daytime dysfunction in the absence of specific physical, mental, or substance-related causes. However, the studies on daytime cognitive functioning of insomnia patients report inconclusive results. This retrospective study aimed to compare the performance of insomnia patients (N = 54) to that of controls (N = 113) in a naturalistic prospective memory task. Task performance was defined by the percentage of times the event-marker button of an actigraph was pressed, at lights-off time and at wake-up time. The performance pattern in the prospective memory task was similar in both groups. In addition, the task was performed better at lights-off time than at wake-up time regardless of group. Post-hoc subgroup analysis showed that there were more insomnia patients who performed the task perfectly (i.e., 100%) than controls. Performance at wake-up time was significantly correlated to objective sleep quality (i.e., sleep efficiency) only in insomnia patients.

Task-Dependent Behavioral Dynamics Make the Case for Temporal Integration in Multiple Strategies during Odor Processing

PubMed Central

Brown, Austin; Mehta, Nisarg; Vujovic, Mark; Amina, Tasneem; Fixsen, Bethany

2017-01-01

Differing results in olfactory-based decision-making research regarding the amount of time that rats and mice use to identify odors have led to some disagreements about odor-processing mechanics, including whether or not rodents use temporal integration (i.e., sniffing longer to identify odors better). Reported differences in behavioral strategies may be due to the different types of tasks used in different laboratories. Some researchers have reported that animals performing two-alternative choice (TAC) tasks need only 1–2 sniffs and do not increase performance with longer sampling. Others have reported that animals performing go/no-go (GNG) tasks increase sampling times and performance for difficult discriminations, arguing for temporal integration. We present results from four experiments comparing GNG and TAC tasks over several behavioral variables (e.g., performance, sampling duration). When rats know only one task, they perform better in GNG than in TAC. However, performance was not statistically different when rats learned and were tested in both tasks. Rats sample odors longer in GNG than in TAC, even when they know both tasks and perform them in the same or different sessions. Longer sampling is associated with better performance for both tasks in difficult discriminations, which supports the case for temporal integration over ≥2–6 sniffs in both tasks. These results illustrate that generalizations from a single task about behavioral or cognitive abilities (e.g., processing, perception) do not capture the full range of complexity and can significantly impact inferences about general abilities in sensory perception. SIGNIFICANCE STATEMENT Behavioral tasks and training and testing history affect measured outcomes in cognitive tests. Rats sample odors longer in a go/no-go (GNG) than in a two-alternative choice (TAC) task, performing better in GNG unless they know both tasks. Odor-sampling time is extended in both tasks when the odors to be discriminated are very similar. Rats may extend sampling time to integrate odor information up to ∼0.5 s (2–6 sniffs). Such factors as task, task parameters, and training history affect decision times and performance, making it important to use multiple tasks when making inferences about sensory or cognitive processing. PMID:28336570

The effects of voice and manual control mode on dual task performance

NASA Technical Reports Server (NTRS)

Wickens, C. D.; Zenyuh, J.; Culp, V.; Marshak, W.

1986-01-01

Two fundamental principles of human performance, compatibility and resource competition, are combined with two structural dichotomies in the human information processing system, manual versus voice output, and left versus right cerebral hemisphere, in order to predict the optimum combination of voice and manual control with either hand, for time-sharing performance of a dicrete and continuous task. Eight right handed male subjected performed a discrete first-order tracking task, time-shared with an auditorily presented Sternberg Memory Search Task. Each task could be controlled by voice, or by the left or right hand, in all possible combinations except for a dual voice mode. When performance was analyzed in terms of a dual-task decrement from single task control conditions, the following variables influenced time-sharing efficiency in diminishing order of magnitude, (1) the modality of control, (discrete manual control of tracking was superior to discrete voice control of tracking and the converse was true with the memory search task), (2) response competition, (performance was degraded when both tasks were responded manually), (3) hemispheric competition, (performance degraded whenever two tasks were controlled by the left hemisphere) (i.e., voice or right handed control). The results confirm the value of predictive models invoice control implementation.

Understanding the role of mind wandering in stress-related working memory impairments.

PubMed

Banks, Jonathan B; Boals, Adriel

2017-08-01

Mind wandering has been identified as a possible cause for stress-related working memory (WM) task impairments following laboratory stressors. The current study attempted to induce mind wandering regarding negative, positive, or neutral events using an expressive writing task and examined the impact on WM task performance. We examined the role of mind wandering in understanding the impact of life stress on WM. Additionally, we explored the role of thought suppression on the relationship between mind wandering and WM. One hundred and fifty participants completed WM measures before (Time 1) and after (Time 2) the writing manipulation. The writing manipulation did not alter mind wandering or WM task performance. Time 1 WM predicted mind wandering during the Time 2 WM task, which subsequently predicted poorer Time 2 WM task performance. The impact of daily life stress on WM was mediated by mind wandering. Trait levels of thought suppression moderated the impact of mind wandering on WM. Specifically, higher levels of suppression resulted in stronger negative impact of mind wandering on WM task performance. Findings are discussed in terms of the impact of mind wandering on WM task performance.

Sleep deprivation and time-on-task performance decrement in the rat psychomotor vigilance task.

PubMed

Oonk, Marcella; Davis, Christopher J; Krueger, James M; Wisor, Jonathan P; Van Dongen, Hans P A

2015-03-01

The rat psychomotor vigilance task (rPVT) was developed as a rodent analog of the human psychomotor vigilance task (hPVT). We examined whether rPVT performance displays time-on-task effects similar to those observed on the hPVT. The rPVT requires rats to respond to a randomly presented light stimulus to obtain a water reward. Rats were water deprived for 22 h prior to each 30-min rPVT session to motivate performance. We analyzed rPVT performance over time on task and as a function of the response-stimulus interval, at baseline and after sleep deprivation. The study was conducted in an academic research vivarium. Male Long-Evans rats were trained to respond to a 0.5 sec stimulus light within 3 sec of stimulus onset. Complete data were available for n = 20 rats. Rats performed the rPVT for 30 min at baseline and after 24 h total sleep deprivation by gentle handling. Compared to baseline, sleep deprived rats displayed increased performance lapses and premature responses, similar to hPVT lapses of attention and false starts. However, in contrast to hPVT performance, the time-on-task performance decrement was not significantly enhanced by sleep deprivation. Moreover, following sleep deprivation, rPVT response times were not consistently increased after short response-stimulus intervals. The rPVT manifests similarities to the hPVT in global performance outcomes, but not in post-sleep deprivation effects of time on task and response-stimulus interval. © 2015 Associated Professional Sleep Societies, LLC.

Characterizing and Mitigating Work Time Inflation in Task Parallel Programs

DOE PAGES

Olivier, Stephen L.; de Supinski, Bronis R.; Schulz, Martin; ...

2013-01-01

Task parallelism raises the level of abstraction in shared memory parallel programming to simplify the development of complex applications. However, task parallel applications can exhibit poor performance due to thread idleness, scheduling overheads, and work time inflation – additional time spent by threads in a multithreaded computation beyond the time required to perform the same work in a sequential computation. We identify the contributions of each factor to lost efficiency in various task parallel OpenMP applications and diagnose the causes of work time inflation in those applications. Increased data access latency can cause significant work time inflation in NUMA systems.more » Our locality framework for task parallel OpenMP programs mitigates this cause of work time inflation. Our extensions to the Qthreads library demonstrate that locality-aware scheduling can improve performance up to 3X compared to the Intel OpenMP task scheduler.« less

Effect of Tai Chi Training on Dual-Tasking Performance That Involves Stepping Down among Stroke Survivors: A Pilot Study.

PubMed

Chan, Wing-Nga; Tsang, William Wai-Nam

2017-01-01

Descending stairs demands attention and neuromuscular control, especially with dual-tasking. Studies have demonstrated that stroke often degrades a survivor's ability to descend stairs. Tai Chi has been shown to improve dual-tasking performance of healthy older adults, but no such study has been conducted in stroke survivors. This study investigated the effect of Tai Chi training on dual-tasking performance that involved stepping down and compared it with that of conventional exercise among stroke survivors. Subjects were randomized into Tai Chi ( n = 9), conventional exercise ( n = 8), and control ( n = 9) groups. Those in the former two groups received 12-week training. Assessments included auditory Stroop test, stepping down test, and dual-tasking test involving both simultaneously. They were evaluated before training (time-1), after training (time-2), and one month after training (time-3). Tai Chi group showed significant improvement in the auditory Stroop test from time-1 to time-3 and the performance was significantly better than that of the conventional exercise group in time-3. No significant effect was found in the stepping down task or dual-tasking in the control group. These results suggest a beneficial effect of Tai Chi training on cognition among stroke survivors without compromising physical task performance in dual-tasking. The effect was better than the conventional exercise group. Nevertheless, further research with a larger sample is warranted.

Multi-AUV autonomous task planning based on the scroll time domain quantum bee colony optimization algorithm in uncertain environment

PubMed Central

Zhang, Rubo; Yang, Yu

2017-01-01

Research on distributed task planning model for multi-autonomous underwater vehicle (MAUV). A scroll time domain quantum artificial bee colony (STDQABC) optimization algorithm is proposed to solve the multi-AUV optimal task planning scheme. In the uncertain marine environment, the rolling time domain control technique is used to realize a numerical optimization in a narrowed time range. Rolling time domain control is one of the better task planning techniques, which can greatly reduce the computational workload and realize the tradeoff between AUV dynamics, environment and cost. Finally, a simulation experiment was performed to evaluate the distributed task planning performance of the scroll time domain quantum bee colony optimization algorithm. The simulation results demonstrate that the STDQABC algorithm converges faster than the QABC and ABC algorithms in terms of both iterations and running time. The STDQABC algorithm can effectively improve MAUV distributed tasking planning performance, complete the task goal and get the approximate optimal solution. PMID:29186166

Multi-AUV autonomous task planning based on the scroll time domain quantum bee colony optimization algorithm in uncertain environment.

PubMed

Li, Jianjun; Zhang, Rubo; Yang, Yu

2017-01-01

Research on distributed task planning model for multi-autonomous underwater vehicle (MAUV). A scroll time domain quantum artificial bee colony (STDQABC) optimization algorithm is proposed to solve the multi-AUV optimal task planning scheme. In the uncertain marine environment, the rolling time domain control technique is used to realize a numerical optimization in a narrowed time range. Rolling time domain control is one of the better task planning techniques, which can greatly reduce the computational workload and realize the tradeoff between AUV dynamics, environment and cost. Finally, a simulation experiment was performed to evaluate the distributed task planning performance of the scroll time domain quantum bee colony optimization algorithm. The simulation results demonstrate that the STDQABC algorithm converges faster than the QABC and ABC algorithms in terms of both iterations and running time. The STDQABC algorithm can effectively improve MAUV distributed tasking planning performance, complete the task goal and get the approximate optimal solution.

The effect of visual-motion time delays on pilot performance in a pursuit tracking task

NASA Technical Reports Server (NTRS)

Miller, G. K., Jr.; Riley, D. R.

1976-01-01

A study has been made to determine the effect of visual-motion time delays on pilot performance of a simulated pursuit tracking task. Three interrelated major effects have been identified: task difficulty, motion cues, and time delays. As task difficulty, as determined by airplane handling qualities or target frequency, increases, the amount of acceptable time delay decreases. However, when relatively complete motion cues are included in the simulation, the pilot can maintain his performance for considerably longer time delays. In addition, the number of degrees of freedom of motion employed is a significant factor.

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.

Performance Trends During Sleep Deprivation on a Tilt-Based Control Task.

PubMed

Bolkhovsky, Jeffrey B; Ritter, Frank E; Chon, Ki H; Qin, Michael

2018-07-01

Understanding human behavior under the effects of sleep deprivation allows for the mitigation of risk due to reduced performance. To further this goal, this study investigated the effects of short-term sleep deprivation using a tilt-based control device and examined whether existing user models accurately predict targeting performance. A task in which the user tilts a surface to roll a ball into a target was developed to examine motor performance. A model was built to predict human performance for this task under various levels of sleep deprivation. Every 2 h, 10 subjects completed the task until they reached 24 h of wakefulness. Performance measurements of this task, which were based on Fitts' law, included movement time, task throughput, and time intercept. The model predicted significant performance decrements over the 24-h period with an increase in movement time (R2 = 0.61), a decrease in throughput (R2 = 0.57), and an increase in time intercept (R2 = 0.60). However, it was found that in experimental trials there was no significant change in movement time (R2 = 0.11), throughput (R2 = 0.15), or time intercept (R2 = 0.27). The results found were unexpected as performance decrement is frequently reported during sleep deprivation. These findings suggest a reexamination of the initial thought of sleep loss leading to a decrement in all aspects of performance.Bolkovsky JB, Ritter FE, Chon KH, Qin M. Performance trends during sleep deprivation on a tilt-based control task. Aerosp Med Hum Perform. 2018; 89(7):626-633.

Effects of total sleep deprivation on divided attention performance

PubMed Central

2017-01-01

Dividing attention across two tasks performed simultaneously usually results in impaired performance on one or both tasks. Most studies have found no difference in the dual-task cost of dividing attention in rested and sleep-deprived states. We hypothesized that, for a divided attention task that is highly cognitively-demanding, performance would show greater impairment during exposure to sleep deprivation. A group of 30 healthy males aged 21–30 years was exposed to 40 h of continuous wakefulness in a laboratory setting. Every 2 h, subjects completed a divided attention task comprising 3 blocks in which an auditory Go/No-Go task was 1) performed alone (single task); 2) performed simultaneously with a visual Go/No-Go task (dual task); and 3) performed simultaneously with both a visual Go/No-Go task and a visually-guided motor tracking task (triple task). Performance on all tasks showed substantial deterioration during exposure to sleep deprivation. A significant interaction was observed between task load and time since wake on auditory Go/No-Go task performance, with greater impairment in response times and accuracy during extended wakefulness. Our results suggest that the ability to divide attention between multiple tasks is impaired during exposure to sleep deprivation. These findings have potential implications for occupations that require multi-tasking combined with long work hours and exposure to sleep loss. PMID:29166387

Effects of total sleep deprivation on divided attention performance.

PubMed

Chua, Eric Chern-Pin; Fang, Eric; Gooley, Joshua J

2017-01-01

Dividing attention across two tasks performed simultaneously usually results in impaired performance on one or both tasks. Most studies have found no difference in the dual-task cost of dividing attention in rested and sleep-deprived states. We hypothesized that, for a divided attention task that is highly cognitively-demanding, performance would show greater impairment during exposure to sleep deprivation. A group of 30 healthy males aged 21-30 years was exposed to 40 h of continuous wakefulness in a laboratory setting. Every 2 h, subjects completed a divided attention task comprising 3 blocks in which an auditory Go/No-Go task was 1) performed alone (single task); 2) performed simultaneously with a visual Go/No-Go task (dual task); and 3) performed simultaneously with both a visual Go/No-Go task and a visually-guided motor tracking task (triple task). Performance on all tasks showed substantial deterioration during exposure to sleep deprivation. A significant interaction was observed between task load and time since wake on auditory Go/No-Go task performance, with greater impairment in response times and accuracy during extended wakefulness. Our results suggest that the ability to divide attention between multiple tasks is impaired during exposure to sleep deprivation. These findings have potential implications for occupations that require multi-tasking combined with long work hours and exposure to sleep loss.

Time-on-task decrements in "steer clear" performance of patients with sleep apnea and narcolepsy

NASA Technical Reports Server (NTRS)

Findley, L. J.; Suratt, P. M.; Dinges, D. F.

1999-01-01

Loss of attention with time-on-task reflects the increasing instability of the waking state during performance in experimentally induced sleepiness. To determine whether patients with disorders of excessive sleepiness also displayed time-on-task decrements indicative of wake state instability, visual sustained attention performance on "Steer Clear," a computerized simple RT driving simulation task, was compared among 31 patients with untreated sleep apnea, 16 patients with narcolepsy, and 14 healthy control subjects. Vigilance decrement functions were generated by analyzing the number of collisions in each of six four-minute periods of Steer Clear task performance in a mixed-model analysis of variance and linear regression equations. As expected, patients had more Steer Clear collisions than control subjects (p=0.006). However, the inter-subject variability in errors among the narcoleptic patients was four-fold that of the apnea patients, and 100-fold that of the controls volunteers; the variance in errors among untreated apnea patients was 27-times that of controls. The results of transformed collision data revealed main effects for group (p=0.006), time-on-task (p=0.001), and a significant interaction (p=0.022). Control subjects showed no clear evidence of increasing collision errors with time-on-task (adjusted R2=0.22), while apnea patients showed a trend toward vigilance decrement (adjusted R2=0.42, p=0.097), and narcolepsy patients evidenced a robust linear vigilance decrement (adjusted R2=0.87, p=0.004). The association of disorders of excessive somnolence with escalating time-on-task decrements makes it imperative that when assessment of neurobehavioral performance is conducted in patients, it involves task durations and analyses that will evaluate the underlying vulnerability of potentially sleepy patients to decrements over time in tasks that require sustained attention and timely responses, both of which are key components in safe driving performance.

How we can measure the non-driving-task engagement in automated driving: Comparing flow experience and workload.

PubMed

Ko, Sang Min; Ji, Yong Gu

2018-02-01

In automated driving, a driver can completely concentrate on non-driving-related tasks (NDRTs). This study investigated the flow experience of a driver who concentrated on NDRTs and tasks that induce mental workload under conditional automation. Participants performed NDRTs under different demand levels: a balanced demand-skill level (fit condition) to induce flow, low-demand level to induce boredom, and high-demand level to induce anxiety. In addition, they performed the additional N-Back task, which artificially induces mental workload. The results showed participants had the longest reaction time when they indicated the highest flow score, and had the longest gaze-on time, road-fixation time, hands-on time, and take-over time under the fit condition. Significant differences were not observed in the driver reaction times in the fit condition and the additional N-Back task, indicating that performing NDRTs that induce a high flow experience could influence driver reaction time similar to performing tasks with a high mental workload. Copyright © 2017. Published by Elsevier Ltd.

The influence of time management skill on the curvilinear relationship between organizational citizenship behavior and task performance.

PubMed

Rapp, Adam A; Bachrach, Daniel G; Rapp, Tammy L

2013-07-01

In this research we integrate resource allocation and social exchange perspectives to build and test theory focusing on the moderating role of time management skill in the nonmonotonic relationship between organizational citizenship behavior (OCB) and task performance. Results from matching survey data collected from 212 employees and 41 supervisors and from task performance metrics collected several months later indicate that the curvilinear association between OCB and task performance is significantly moderated by employees' time management skill. Implications for theory and practice are discussed. PsycINFO Database Record (c) 2013 APA, all rights reserved.

The effect of visual-motion time-delays on pilot performance in a simulated pursuit tracking task

NASA Technical Reports Server (NTRS)

Miller, G. K., Jr.; Riley, D. R.

1977-01-01

An experimental study was made to determine the effect on pilot performance of time delays in the visual and motion feedback loops of a simulated pursuit tracking task. Three major interrelated factors were identified: task difficulty either in the form of airplane handling qualities or target frequency, the amount and type of motion cues, and time delay itself. In general, the greater the task difficulty, the smaller the time delay that could exist without degrading pilot performance. Conversely, the greater the motion fidelity, the greater the time delay that could be tolerated. The effect of motion was, however, pilot dependent.

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.

Erroneous knowledge of results affects decision and memory processes on timing tasks.

PubMed

Ryan, Lawrence J; Fritz, Matthew S

2007-12-01

On mental timing tasks, erroneous knowledge of results (KR) leads to incorrect performance accompanied by the subjective judgment of accurate performance. Using the start-stop technique (an analogue of the peak interval procedure) with both reproduction and production timing tasks, the authors analyze what processes erroneous KR alters. KR provides guidance (performance error information) that lowers decision thresholds. Erroneous KR also provides targeting information that alters response durations proportionately to the magnitude of the feedback error. On the production task, this shift results from changes in the reference memory, whereas on the reproduction task this shift results from changes in the decision threshold for responding. The idea that erroneous KR can alter different cognitive processes on related tasks is supported by the authors' demonstration that the learned strategies can transfer from the reproduction task to the production task but not visa versa. Thus effects of KR are both task and context dependent.

The Vigilance Decrement in Executive Function Is Attenuated When Individual Chronotypes Perform at Their Optimal Time of Day

PubMed Central

Lara, Tania; Madrid, Juan Antonio; Correa, Ángel

2014-01-01

Time of day modulates our cognitive functions, especially those related to executive control, such as the ability to inhibit inappropriate responses. However, the impact of individual differences in time of day preferences (i.e. morning vs. evening chronotype) had not been considered by most studies. It was also unclear whether the vigilance decrement (impaired performance with time on task) depends on both time of day and chronotype. In this study, morning-type and evening-type participants performed a task measuring vigilance and response inhibition (the Sustained Attention to Response Task, SART) in morning and evening sessions. The results showed that the vigilance decrement in inhibitory performance was accentuated at non-optimal as compared to optimal times of day. In the morning-type group, inhibition performance decreased linearly with time on task only in the evening session, whereas in the morning session it remained more accurate and stable over time. In contrast, inhibition performance in the evening-type group showed a linear vigilance decrement in the morning session, whereas in the evening session the vigilance decrement was attenuated, following a quadratic trend. Our findings imply that the negative effects of time on task in executive control can be prevented by scheduling cognitive tasks at the optimal time of day according to specific circadian profiles of individuals. Therefore, time of day and chronotype influences should be considered in research and clinical studies as well as real-word situations demanding executive control for response inhibition. PMID:24586404

PAVENET OS: A Compact Hard Real-Time Operating System for Precise Sampling in Wireless Sensor Networks

NASA Astrophysics Data System (ADS)

Saruwatari, Shunsuke; Suzuki, Makoto; Morikawa, Hiroyuki

The paper shows a compact hard real-time operating system for wireless sensor nodes called PAVENET OS. PAVENET OS provides hybrid multithreading: preemptive multithreading and cooperative multithreading. Both of the multithreading are optimized for two kinds of tasks on wireless sensor networks, and those are real-time tasks and best-effort ones. PAVENET OS can efficiently perform hard real-time tasks that cannot be performed by TinyOS. The paper demonstrates the hybrid multithreading realizes compactness and low overheads, which are comparable to those of TinyOS, through quantitative evaluation. The evaluation results show PAVENET OS performs 100 Hz sensor sampling with 0.01% jitter while performing wireless communication tasks, whereas optimized TinyOS has 0.62% jitter. In addition, PAVENET OS has a small footprint and low overheads (minimum RAM size: 29 bytes, minimum ROM size: 490 bytes, minimum task switch time: 23 cycles).

Effects of System Timing Parameters on Operator Performance in a Personnel Records Task

DTIC Science & Technology

1981-03-01

work sampling, embedded performance measures, and operator satisfaction ratings) are needed to provide a complete analysis of the effects of the four...HFL-8 l-l/NPRDC-8 1-1 March 1981 EFFECTS OF SYSTEM TIMING PARAMETERS ON OPERATOR PERFORMANCE IN A PERSONNEL RECORDS TASK Robert C. Williges Beverly H...and Subtitle) S. TYPE OF REPORT & PERIOD COVERED EFFECTS OF SYSTEM TIMING PARAMETERS ON OPERATOR PERFORMANCE IN A PERSONNEL RECORDS TASK Final

The cortisol awakening response is associated with performance of a serial sequence reaction time task.

PubMed

Hodyl, Nicolette A; Schneider, Luke; Vallence, Ann-Maree; Clow, Angela; Ridding, Michael C; Pitcher, Julia B

2016-02-01

There is emerging evidence of a relationship between the cortisol awakening response (CAR) and the neural mechanisms underlying learning and memory. The aim of this study was to determine whether the CAR is associated with acquisition, retention and overnight consolidation or improvement of a serial sequence reaction time task. Salivary samples were collected at 0, 15, 30 and 45 min after awakening in 39 healthy adults on 2 consecutive days. The serial sequence reaction time task was repeated each afternoon. Participants completed the perceived stress scale and provided salivary samples prior to testing for cortisol assessment. While the magnitude of the CAR (Z score) was not associated with either baseline performance or the timed improvement during task acquisition of the serial sequence task, a positive correlation was observed with reaction times during the stable performance phase on day 1 (r=0.373, p=0.019). Residuals derived from the relationship between baseline and stable phase reaction times on day 1 were used as a surrogate for the degree of learning: these residuals were also correlated with the CAR mean increase on day 1 (r=0.357, p=0.048). Task performance on day 2 was not associated with the CAR obtained on this same day. No association was observed between the perceived stress score, cortisol at testing or task performance. These data indicate that a smaller CAR in healthy adults is associated with a greater degree of learning and faster performance of a serial sequence reaction time task. These results support recognition of the CAR as an important factor contributing to cognitive performance throughout the day. Copyright © 2015 Elsevier B.V. All rights reserved.

Age-related differences in dual task performance: A cross-sectional study on women.

PubMed

Brustio, Paolo R; Magistro, Daniele; Rabaglietti, Emanuela; Liubicich, Monica E

2017-02-01

Simultaneous performances of motor and attention-demanding tasks are common in activities of everyday life. The present cross-sectional study examined the changes and age-related differences on mobility performance with an additional cognitive or motor task, and evaluated the relative dual-task cost (DTC) on the motor performance in young, middle-aged and older women. A total of 30 young (mean age 25.12 ± 3.00 years), 30 middle-aged (mean age 47.82 ± 5.06 years) and 30 older women (mean age 72.74 ± 5.95 years) were recruited. Participants carried out: (i) single task: Timed Up & Go Test; (ii) cognitive dual-task: Timed Up & Go Test while counting backwards by three; (iii) manual dual-task: Timed Up & Go Test while carrying a glass of water. A repeated measures anova with between-factor as age groups and within-factor as tasks was carried out to assess the effect of aging on the performance of mobility tasks. DTC was calculated as ([performance in single-task - performance in dual-task] / performance in single task) × 100%. One-way ancova were carried out to compare the DTC among the three age groups. A significant interaction between age groups and task (F 4,172  = 6.716, P < 0.001, partial η 2  = 0.135) was observed. Specifically, older women showed a worse mobility performance under dual-task condition compared with young and middle-aged groups. Furthermore, DTC differences in cognitive task were observed in older women compared with younger and middle-aged women (F 2,86  = 7.649, P < 0.001, partial η 2  = 0.151), but not in manual task. Dual-task conditions might affect mobility performance differently across the lifespan, and could be particularly challenging in older women. Geriatr Gerontol Int 2017; 17: 315-321. © 2015 Japan Geriatrics Society.

Implicit Coordination Strategies for Effective Team Communication.

PubMed

Butchibabu, Abhizna; Sparano-Huiban, Christopher; Sonenberg, Liz; Shah, Julie

2016-06-01

We investigated implicit communication strategies for anticipatory information sharing during team performance of tasks with varying degrees of complexity. We compared the strategies used by teams with the highest level of performance to those used by the lowest-performing teams to evaluate the frequency and methods of communications used as a function of task structure. High-performing teams share information by anticipating the needs of their teammates rather than explicitly requesting the exchange of information. As the complexity of a task increases to involve more interdependence among teammates, the impact of coordination on team performance also increases. This observation motivated us to conduct a study of anticipatory information sharing as a function of task complexity. We conducted an experiment in which 13 teams of four people performed collaborative search-and-deliver tasks with varying degrees of complexity in a simulation environment. We elaborated upon prior characterizations of communication as implicit versus explicit by dividing implicit communication into two subtypes: (a) deliberative/goal information and (b) reactive status updates. We then characterized relationships between task structure, implicit communication, and team performance. We found that the five teams with the fastest task completion times and lowest idle times exhibited higher rates of deliberative communication versus reactive communication during high-complexity tasks compared with the five teams with the slowest completion times and longest idle times (p = .039). Teams in which members proactively communicated information about their next goal to teammates exhibited improved team performance. The findings from our work can inform the design of communication strategies for team training to improve performance of complex tasks. © 2016, Human Factors and Ergonomics Society.

Age-Related Effects of Study Time Allocation on Memory Performance in a Verbal and a Spatial Task

ERIC Educational Resources Information Center

Krueger, Lacy E.

2012-01-01

Past studies have suggested that study time allocation partially mediates age relations on memory performance in a verbal task. To identify whether this applied to a different material modality, participants ages 20-87 completed a spatial task in addition to a traditional verbal task. In both the verbal and the spatial task, increased age was…

Task Training Emphasis for Determining Training Priority.

DTIC Science & Technology

1987-08-01

the relative time spent on tasks performed in their current jobs. Supervisors also rated the tasks on several different task factors, including a new... different task factors, including Task Difficulty, Probable Consequences of Inadequate Performance, Task Delay Tolerance, and Recommended Training Emphasis...3 11. APPROACH. .. ..... ..... ...... ..... ..... ...... ...... 4 III. METHOD

Erroneous Knowledge of Results Affects Decision and Memory Processes on Timing Tasks

ERIC Educational Resources Information Center

Ryan, Lawrence J.; Fritz, Matthew S.

2007-01-01

On mental timing tasks, erroneous knowledge of results (KR) leads to incorrect performance accompanied by the subjective judgment of accurate performance. Using the start-stop technique (an analogue of the peak interval procedure) with both reproduction and production timing tasks, the authors analyze what processes erroneous KR alters. KR…

Time-sharing ability in complex performance : an expanded replication.

DOT National Transportation Integrated Search

1978-09-01

Factor analyses were performed on data from 51 subjects tested on the CAMI Multiple Task Performance Battery (MTPB). Five different complex performance task combinations were used as well as the six individual MTPB tasks performed by themselves. The ...

Effect of time delay on surgical performance during telesurgical manipulation.

PubMed

Fabrizio, M D; Lee, B R; Chan, D Y; Stoianovici, D; Jarrett, T W; Yang, C; Kavoussi, L R

2000-03-01

Telementoring allows a less experienced surgeon to benefit from an expert surgical consultation, reducing cost, travel, and the learning curve associated with new procedures. However, there are several technical limitations that affect practical applications. One potentially serious problem is the time delay that occurs any time data are transferred across long distances. To date, the effect of time delay on surgical performance has not been studied. A two-phase trial was designed to examine the effect of time delay on surgical performance. In the first phase, a series of tasks was performed, and the numbers of robotic movements required for completion was counted. Programmed incremental time delays were made in audiovisual acquisition and robotic controls. The number of errors made while performing each task at various time delay intervals was noted. In the second phase, a remote surgeon in Baltimore performed the tasks 9000 miles away in Singapore. The number of errors made was recorded. As the time delay increased, the number of operator errors increased. The accuracy needed to perform remote robotic procedures was diminished as the time delay increased. A learning curve did exist for each task, but as the time delay interval increased, it took longer to complete the task. Time delay does affect surgical performance. There is an acceptable delay of <700 msec in which surgeons can compensate for this phenomenon. Clinical studies will be needed to evaluate the true impact of time delay.

Single-task and dual-task tandem gait test performance after concussion.

PubMed

Howell, David R; Osternig, Louis R; Chou, Li-Shan

2017-07-01

To compare single-task and dual-task tandem gait test performance between athletes after concussion with controls on observer-timed, spatio-temporal, and center-of-mass (COM) balance control measurements. Ten participants (19.0±5.5years) were prospectively identified and completed a tandem gait test protocol within 72h of concussion and again 1 week, 2 weeks, 1 month, and 2 months post-injury. Seven uninjured controls (20.0±4.5years) completed the same protocol in similar time increments. Tandem gait test trials were performed with (dual-task) and without (single-task) concurrently performing a cognitive test as whole-body motion analysis was performed. Outcome variables included test completion time, average tandem gait velocity, cadence, and whole-body COM frontal plane displacement. Concussion participants took significantly longer to complete the dual-task tandem gait test than controls throughout the first 2 weeks post-injury (mean time=16.4 [95% CI: 13.4-19.4] vs. 10.1 [95% CI: 6.4-13.7] seconds; p=0.03). Single-task tandem gait times were significantly lower 72h post-injury (p=0.04). Dual-task cadence was significantly lower for concussion participants than controls (89.5 [95% CI: 68.6-110.4] vs. 127.0 [95% CI: 97.4-156.6] steps/minute; p=0.04). Moderately-high to high correlations between tandem gait test time and whole-body COM medial-lateral displacement were detected at each time point during dual-task gait (r s =0.70-0.93; p=0.03-0.001). Adding a cognitive task during the tandem gait test resulted in longer detectable deficits post-concussion compared to the traditional single-task tandem gait test. As a clinical tool to assess dynamic motor function, tandem gait may assist with return to sport decisions after concussion. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Measuring listening effort: driving simulator vs. simple dual-task paradigm

PubMed Central

Wu, Yu-Hsiang; Aksan, Nazan; Rizzo, Matthew; Stangl, Elizabeth; Zhang, Xuyang; Bentler, Ruth

2014-01-01

Objectives The dual-task paradigm has been widely used to measure listening effort. The primary objectives of the study were to (1) investigate the effect of hearing aid amplification and a hearing aid directional technology on listening effort measured by a complicated, more real world dual-task paradigm, and (2) compare the results obtained with this paradigm to a simpler laboratory-style dual-task paradigm. Design The listening effort of adults with hearing impairment was measured using two dual-task paradigms, wherein participants performed a speech recognition task simultaneously with either a driving task in a simulator or a visual reaction-time task in a sound-treated booth. The speech materials and road noises for the speech recognition task were recorded in a van traveling on the highway in three hearing aid conditions: unaided, aided with omni directional processing (OMNI), and aided with directional processing (DIR). The change in the driving task or the visual reaction-time task performance across the conditions quantified the change in listening effort. Results Compared to the driving-only condition, driving performance declined significantly with the addition of the speech recognition task. Although the speech recognition score was higher in the OMNI and DIR conditions than in the unaided condition, driving performance was similar across these three conditions, suggesting that listening effort was not affected by amplification and directional processing. Results from the simple dual-task paradigm showed a similar trend: hearing aid technologies improved speech recognition performance, but did not affect performance in the visual reaction-time task (i.e., reduce listening effort). The correlation between listening effort measured using the driving paradigm and the visual reaction-time task paradigm was significant. The finding showing that our older (56 to 85 years old) participants’ better speech recognition performance did not result in reduced listening effort was not consistent with literature that evaluated younger (approximately 20 years old), normal hearing adults. Because of this, a follow-up study was conducted. In the follow-up study, the visual reaction-time dual-task experiment using the same speech materials and road noises was repeated on younger adults with normal hearing. Contrary to findings with older participants, the results indicated that the directional technology significantly improved performance in both speech recognition and visual reaction-time tasks. Conclusions Adding a speech listening task to driving undermined driving performance. Hearing aid technologies significantly improved speech recognition while driving, but did not significantly reduce listening effort. Listening effort measured by dual-task experiments using a simulated real-world driving task and a conventional laboratory-style task was generally consistent. For a given listening environment, the benefit of hearing aid technologies on listening effort measured from younger adults with normal hearing may not be fully translated to older listeners with hearing impairment. PMID:25083599

Effect of type of cue, type of response, time delay and two different ongoing tasks on prospective memory functioning after acquired brain injury.

PubMed

Raskin, Sarah A; Buckheit, Carol A; Waxman, Amanda

2012-01-01

Failures of prospective memory (PM) are one of the most frequent, and least studied, sequelae of brain injury. PM, also referred to as memory for intentions, is the ability to remember to carry out a future task. Successful completion of a PM task requires the ability to monitor time, keep the action to be performed periodically in awareness, remember the task to be performed, and initiate the action. Although PM has been shown to be a common difficulty after brain injury, it remains unknown which aspects of performance are impaired. In this study, the performance of 25 individuals with brain injury and that of 25 healthy participants were measured separately on the following variables: time until completion of the task, difficulty of the ongoing task being performed while waiting, whether the task to be performed is an action or is verbal, and whether the cue to perform the task is the passing of a particular amount of time (e.g., 10 minutes) or is an external cue (e.g., an alarm sounding). Individuals with brain injury demonstrated impairment compared to healthy adults on virtually all variables. PM performance was also compared to a battery of standard neuropsychological measures of attention, memory, and executive functions, and to self-report measures of PM functioning, in order to determine the underlying cognitive deficits responsible for poor PM performance, if any. PM performance was correlated with measures of executive functioning but not to self-report measures of PM functioning. Implications are discussed in terms of cognitive rehabilitation recommendations.

Factors Influencing Children's Performances of a Steady-State Bimanual Coordination Task

ERIC Educational Resources Information Center

Lantero, Dawn A.; Ringenbach, Shannon D.

2009-01-01

Children ages 4, 6, and 8 years and adults performed self-selected, continuous, unimanual and bimanual coordination tasks for 30 s. The length of time performing the task was investigated as a potential control parameter. As hypothesized, all groups spent less time in antiphase than in in-phase coordination as the trial continued. These results…

Mental workload and cognitive task automaticity: an evaluation of subjective and time estimation metrics.

PubMed

Liu, Y; Wickens, C D

1994-11-01

The evaluation of mental workload is becoming increasingly important in system design and analysis. The present study examined the structure and assessment of mental workload in performing decision and monitoring tasks by focusing on two mental workload measurements: subjective assessment and time estimation. The task required the assignment of a series of incoming customers to the shortest of three parallel service lines displayed on a computer monitor. The subject was either in charge of the customer assignment (manual mode) or was monitoring an automated system performing the same task (automatic mode). In both cases, the subjects were required to detect the non-optimal assignments that they or the computer had made. Time pressure was manipulated by the experimenter to create fast and slow conditions. The results revealed a multi-dimensional structure of mental workload and a multi-step process of subjective workload assessment. The results also indicated that subjective workload was more influenced by the subject's participatory mode than by the factor of task speed. The time estimation intervals produced while performing the decision and monitoring tasks had significantly greater length and larger variability than those produced while either performing no other tasks or performing a well practised customer assignment task. This result seemed to indicate that time estimation was sensitive to the presence of perceptual/cognitive demands, but not to response related activities to which behavioural automaticity has developed.

Real-Time Performance Feedback for the Manual Control of Spacecraft

NASA Astrophysics Data System (ADS)

Karasinski, John Austin

Real-time performance metrics were developed to quantify workload, situational awareness, and manual task performance for use as visual feedback to pilots of aerospace vehicles. Results from prior lunar lander experiments with variable levels of automation were replicated and extended to provide insights for the development of real-time metrics. Increased levels of automation resulted in increased flight performance, lower workload, and increased situational awareness. Automated Speech Recognition (ASR) was employed to detect verbal callouts as a limited measure of subjects' situational awareness. A one-dimensional manual tracking task and simple instructor-model visual feedback scheme was developed. This feedback was indicated to the operator by changing the color of a guidance element on the primary flight display, similar to how a flight instructor points out elements of a display to a student pilot. Experiments showed that for this low-complexity task, visual feedback did not change subject performance, but did increase the subjects' measured workload. Insights gained from these experiments were applied to a Simplified Aid for EVA Rescue (SAFER) inspection task. The effects of variations of an instructor-model performance-feedback strategy on human performance in a novel SAFER inspection task were investigated. Real-time feedback was found to have a statistically significant effect of improving subject performance and decreasing workload in this complicated four degree of freedom manual control task with two secondary tasks.

The Effect of Two-dimensional and Stereoscopic Presentation on Middle School Students' Performance of Spatial Cognition Tasks

NASA Astrophysics Data System (ADS)

Price, Aaron; Lee, Hee-Sun

2010-02-01

We investigated whether and how student performance on three types of spatial cognition tasks differs when worked with two-dimensional or stereoscopic representations. We recruited nineteen middle school students visiting a planetarium in a large Midwestern American city and analyzed their performance on a series of spatial cognition tasks in terms of response accuracy and task completion time. Results show that response accuracy did not differ between the two types of representations while task completion time was significantly greater with the stereoscopic representations. The completion time increased as the number of mental manipulations of 3D objects increased in the tasks. Post-interviews provide evidence that some students continued to think of stereoscopic representations as two-dimensional. Based on cognitive load and cue theories, we interpret that, in the absence of pictorial depth cues, students may need more time to be familiar with stereoscopic representations for optimal performance. In light of these results, we discuss potential uses of stereoscopic representations for science learning.

Effects of Non-Driving Related Task Modalities on Takeover Performance in Highly Automated Driving.

PubMed

Wandtner, Bernhard; Schömig, Nadja; Schmidt, Gerald

2018-04-01

Aim of the study was to evaluate the impact of different non-driving related tasks (NDR tasks) on takeover performance in highly automated driving. During highly automated driving, it is allowed to engage in NDR tasks temporarily. However, drivers must be able to take over control when reaching a system limit. There is evidence that the type of NDR task has an impact on takeover performance, but little is known about the specific task characteristics that account for performance decrements. Thirty participants drove in a simulator using a highly automated driving system. Each participant faced five critical takeover situations. Based on assumptions of Wickens's multiple resource theory, stimulus and response modalities of a prototypical NDR task were systematically manipulated. Additionally, in one experimental group, the task was locked out simultaneously with the takeover request. Task modalities had significant effects on several measures of takeover performance. A visual-manual texting task degraded performance the most, particularly when performed handheld. In contrast, takeover performance with an auditory-vocal task was comparable to a baseline without any task. Task lockout was associated with faster hands-on-wheel times but not altered brake response times. Results showed that NDR task modalities are relevant factors for takeover performance. An NDR task lockout was highly accepted by the drivers and showed moderate benefits for the first takeover reaction. Knowledge about the impact of NDR task characteristics is an enabler for adaptive takeover concepts. In addition, it might help regulators to make decisions on allowed NDR tasks during automated driving.

Predictors of Time-Based Prospective Memory in Children

ERIC Educational Resources Information Center

Mackinlay, Rachael J.; Kliegel, Matthias; Mantyla, Timo

2009-01-01

This study identified age differences in time-based prospective memory performance in school-aged children and explored possible cognitive correlates of age-related performance. A total of 56 7- to 12-year-olds performed a prospective memory task in which prospective memory accuracy, ongoing task performance, and time monitoring were assessed.…

Saccadic performance in questionnaire-identified schizotypes over time.

PubMed

Gooding, Diane C; Shea, Heather B; Matts, Christie W

2005-02-28

In the present study, 121 young adults (mean age=19 years), hypothesized to be at varying levels of risk for psychosis on the basis of their psychometric profiles, were administered saccadic (antisaccade and refixation) tasks at two separate assessments. At Time 1, individuals posited to be at heightened risk for the later development of schizophrenia-spectrum disorders (i.e., those individuals with elevated Social Anhedonia Scale [SAS] scores) produced significantly more antisaccade task errors than the controls. Despite apparent improvement in antisaccade task performance from initial testing to the follow-up (mean test-retest interval=59 months) across all groups, the Social Anhedonia (SocAnh) group continued to produce significantly more errors than the control group. The antisaccade task performance of the control group showed good temporal stability (Pearson's r=0.70, ICC=0.52), and the SocAnh group's performance showed excellent temporal stability (Pearson's r=0.85, ICC=0.83). The results of this investigation are twofold: First, antisaccade task performance is temporally stable, even in psychometrically identified schizotypes over long test-retest intervals; and secondly, Social Anhedonia Scale scores as well as Time 1 antisaccade task accuracy accounted for much of the variability in Time 2 antisaccade task performance. These findings add to the growing body of literature suggesting that antisaccade task deficits may serve as an endophenotypic marker of a schizophrenia diathesis.

Dual Motor-Cognitive Virtual Reality Training Impacts Dual-Task Performance in Freezing of Gait.

PubMed

Killane, Isabelle; Fearon, Conor; Newman, Louise; McDonnell, Conor; Waechter, Saskia M; Sons, Kristian; Lynch, Timothy; Reilly, Richard B

2015-11-01

Freezing of gait (FOG), an episodic gait disturbance characterized by the inability to generate effective stepping, occurs in more than half of Parkinson's disease patients. It is associated with both executive dysfunction and attention and becomes most evident during dual tasking (performing two tasks simultaneously). This study examined the effect of dual motor-cognitive virtual reality training on dual-task performance in FOG. Twenty community dwelling participants with Parkinson's disease (13 with FOG, 7 without FOG) participated in a pre-assessment, eight 20-minute intervention sessions, and a post-assessment. The intervention consisted of a virtual reality maze (DFKI, Germany) through which participants navigated by stepping-in-place on a balance board (Nintendo, Japan) under time pressure. This was combined with a cognitive task (Stroop test), which repeatedly divided participants' attention. The primary outcome measures were pre- and post-intervention differences in motor (stepping time, symmetry, rhythmicity) and cognitive (accuracy, reaction time) performance during single- and dual-tasks. Both assessments consisted of 1) a single cognitive task 2) a single motor task, and 3) a dual motor-cognitive task. Following the intervention, there was significant improvement in dual-task cognitive and motor parameters (stepping time and rhythmicity), dual-task effect for those with FOG and a noteworthy improvement in FOG episodes. These improvements were less significant for those without FOG. This is the first study to show benefit of a dual motor-cognitive approach on dual-task performance in FOG. Advances in such virtual reality interventions for home use could substantially improve the quality of life for patients who experience FOG.

Evaluation of 2 cognitive abilities tests in a dual-task environment

NASA Technical Reports Server (NTRS)

Vidulich, M. A.; Tsang, P. S.

1986-01-01

Most real world operators are required to perform multiple tasks simultaneously. In some cases, such as flying a high performance aircraft or trouble shooting a failing nuclear power plant, the operator's ability to time share or process in parallel" can be driven to extremes. This has created interest in selection tests of cognitive abilities. Two tests that have been suggested are the Dichotic Listening Task and the Cognitive Failures Questionnaire. Correlations between these test results and time sharing performance were obtained and the validity of these tests were examined. The primary task was a tracking task with dynamically varying bandwidth. This was performed either alone or concurrently with either another tracking task or a spatial transformation task. The results were: (1) An unexpected negative correlation was detected between the two tests; (2) The lack of correlation between either test and task performance made the predictive utility of the tests scores appear questionable; (3) Pilots made more errors on the Dichotic Listening Task than college students.

Effects of dual-task balance training on postural performance in patients with Multiple Sclerosis: a double-blind, randomized controlled pilot trial.

PubMed

Monjezi, Saeideh; Negahban, Hossein; Tajali, Shirin; Yadollahpour, Nava; Majdinasab, Nastaran

2017-02-01

To investigate the effects of dual-task balance training on postural performance in patients with multiple sclerosis as compared with single-task balance training. Double-blind, pretest-posttest, randomized controlled pilot trial. Local Multiple Sclerosis Society. A total of 47 patients were randomly assigned to two equal groups labeled as single-task training and dual-task training groups. All patients received supervised balance training sessions, 3 times per week for 4 weeks. The patients in the single-task group performed balance activities, alone. However, patients in dual-task group practiced balance activities while simultaneously performing cognitive tasks. The 10-Meter Walk Test and Timed Up-and-Go under single-task and dual-task conditions, in addition to Activities-specific Balance Confidence, Berg Balance Scale, and Functional Gait Assessment were assessed pre-, and post intervention and also 6-weeks after the end of intervention. Only 38 patients completed the treatment plan. There was no difference in the amount of improvement seen between the two study groups. In both groups there was a significant effect of time for dual-10 Meter Walk Test (F 1, 36 =11.33, p=0.002) and dual-Timed Up-and-Go (F 1, 36 =14.27, p=0.001) but not for their single-tasks. Moreover, there was a significant effect of time for Activities-specific Balance Confidence, Berg Balance Scale, and Functional Gait Assessment ( P<0.01). This pilot study did not show more benefits from undertaking dual-task training than single-task training. A power analysis showed 71 patients per group would be needed to determine whether there was a clinically relevant difference for dual-task gait speed between the groups.

Mediators of methylphenidate effects on math performance in children with attention-deficit hyperactivity disorder.

PubMed

Froehlich, Tanya E; Antonini, Tanya N; Brinkman, William B; Langberg, Joshua M; Simon, John O; Adams, Ryan; Fredstrom, Bridget; Narad, Megan E; Kingery, Kathleen M; Altaye, Mekibib; Matheson, Heather; Tamm, Leanne; Epstein, Jeffery N

2014-01-01

Stimulant medications, such as methylphenidate (MPH), improve the academic performance of children with attention-deficit hyperactivity disorder (ADHD). However, the mechanism by which MPH exerts an effect on academic performance is unclear. We examined MPH effects on math performance and investigated possible mediation of MPH effects by changes in time on-task, inhibitory control, selective attention, and reaction time variability. Children with ADHD aged 7 to 11 years (N = 93) completed a timed math worksheet (with problems tailored to each individual's level of proficiency) and 2 neuropsychological tasks (Go/No-Go and Child Attention Network Test) at baseline, then participated in a 4-week, randomized, controlled, titration trial of MPH. Children were then randomly assigned to their optimal MPH dose or placebo for 1 week (administered double-blind) and repeated the math and neuropsychological tasks (posttest). Baseline and posttest videorecordings of children performing the math task were coded to assess time on-task. Children taking MPH completed 23 more math problems at posttest compared to baseline, whereas the placebo group completed 24 fewer problems on posttest versus baseline, but the effects on math accuracy (percent correct) did not differ. Path analyses revealed that only change in time on-task was a significant mediator of MPH's improvements in math productivity. MPH-derived math productivity improvements may be explained in part by increased time spent on-task, rather than improvements in neurocognitive parameters, such as inhibitory control, selective attention, or reaction time variability.

An investigation of time-sharing ability as a factor in complex performance.

DOT National Transportation Integrated Search

1976-05-01

Thirty-nine men were tested on a total of six tasks; performance was measured on each task presented individually and on two complex tasks made up of three-task subsets. The tasks measured monitoring, arithmetic, pattern-discrimination, tracking, and...

Preferential processing of task-irrelevant beloved-related information and task performance: Two event-related potential studies.

PubMed

Langeslag, Sandra J E; van Strien, Jan W

2017-09-18

People who are in love have better attention for beloved-related information, but report having trouble focusing on other tasks, such as (home)work. So, romantic love can both improve and hurt cognition. Emotional information is preferentially processed, which improves task performance when the information is task-relevant, but hurts task performance when it is task-irrelevant. Because beloved-related information is highly emotional, the effects of romantic love on cognition may resemble these effects of emotion on cognition. We examined whether beloved-related information is preferentially processed even when it is task-irrelevant and whether this hurts task performance. In two event-related potential studies, participants who had recently fallen in love performed a visuospatial short-term memory task. Task-irrelevant beloved, friend, and stranger faces were presented during maintenance (Study 1), or encoding (Study 2). The Early Posterior Negativity (EPN) reflecting early automatic attentional capturing and the Late Positive Potential (LPP) reflecting sustained motivated attention were largest for beloved pictures. Thus, beloved pictures are preferentially processed even when they are task-irrelevant. Task performance and reaction times did not differ between beloved, friend, and stranger conditions. Nevertheless, self-reported obsessive thinking about the beloved tended to correlate negatively with task performance, and positively with reaction times, across conditions. So, although task-irrelevant beloved-related information does not impact task performance, more obsessive thinking about the beloved might relate to poorer and slower overall task performance. More research is needed to clarify why people experience trouble focusing on beloved-unrelated tasks and how this negative effect of love on cognition could be reduced. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relationships Among Lower Body Strength, Power, and Performance of Functional Tasks

NASA Technical Reports Server (NTRS)

Ploutz-Snyder, Lori; Ryder, J.; Hackney, K.; Scott-Pandorf, M.; Redd, E.; Buxton, R.; Bloomberg, J.

2010-01-01

There is a large degree of variability among crewmembers with respect to decrements in muscle strength and power following long duration spaceflight, ranging from 0 to approx.30% reductions. The purpose of this study was to investigate the influence of varying decrements in lower body muscle strength and power (relative to body weight) on the performance of 2 occupationally relevant tasks (ladder climb and supine egress & walk). Seventeen participants with leg strength similar to US crewmembers performed a leg press power test, an isokinetic knee extension strength test and they were asked to complete the 2 functional tasks as quickly as possible. On additional test days the participants were asked to repeat the functional tasks under 3 conditions where a different external load was applied each time using a weighted suit in order to experimentally manipulate participants strength/body weight and power/body weight ratios. The weight in the suit ranged from 20-120% of body weight and was distributed in proportion to limb segment weights to minimize changes in center of gravity. The ladder task consisted of climbing 40 rungs on a ladder treadmill as fast as possible. The supine egress & walk task consisted of rising from a supine position and walking through an obstacle course. Results show a relatively linear relationship between strength/body weight and task time and power/body weight with task time such that the fastest performance times are associated with higher strength and power with about half the variance in task time is accounted for by a single variable (either strength or power). For the average person, a 20% reduction in power/body weight (from 18 to 14.4 W/kg) induces an increase (slowing) of about 10 seconds in the ladder climb task from 14 to 24 seconds (approx.70%) and a slowing of the supine egress & walk task from 14 to 21 seconds (approx.50%). Similar relationships were observed with strength/body weight and task performance. For the average person, a 20% reduction in strength/body weight (from 2.1 to 1.7 Nm/kg) resulted in a slowing of the ladder climb from 10.5 to 24 seconds (approx.128%) and a slowing of the supine egress & walk from 11 to 20 seconds (approx.82%). These data suggest that the single variable of either low body muscle strength or power, relative to body weight is predictive of about 50% of the variance in task performance time, and that considerable slowing in task performance is associated with relatively typical decrements in muscle performance seen with long duration spaceflight. The observation of a relatively linear relationship between strength/power and task time suggests that across the full spectrum of initial crew strengths and typical decrements in strength previously observed, that task performance would be expected to be slowed following long duration spaceflight. These data will be confirmed in actual spaceflight with subsequent studies.

Cognitive timing: neuropsychology and anatomic basis.

PubMed

Coslett, H Branch; Shenton, Jeff; Dyer, Tamarah; Wiener, Martin

2009-02-13

We report data from 31 subjects with focal hemisphere lesions (15 left hemisphere) as well as 16 normal controls on a battery of tasks assessing the estimation, production and reproduction of time intervals ranging from 2-12 s. Both visual and auditory stimuli were employed for the estimation and production tasks. First, ANOVAs were performed to assess the effect of stimulus modality on estimation and production tasks; a significant effect of stimulus modality was observed for the production but not the estimation task. Second, accuracy was significantly different for the 2 s interval as compared to longer intervals. Subsequent analyses of the data from 4-12 s stimuli demonstrated that patients with brain lesions were more variable than controls on the estimation and reproduction tasks. Additionally, patients with brain lesions but not controls exhibited significant differences in performance on the different tasks; patients with brain lesions under-produced but over-estimated time intervals of 4-12 s but performed relatively well on the reproduction task, a pattern of performance consistent with a "fast clock". There was a significant correlation between impaired performance and lesions of the parietal lobe but there was no effect of laterality of lesion or correlation between lateral frontal lobe lesions and impairment on any task.

The impact of cognitive control on children's goal monitoring in a time-based prospective memory task.

PubMed

Mahy, Caitlin E V; Voigt, Babett; Ballhausen, Nicola; Schnitzspahn, Katharina; Ellis, Judi; Kliegel, Matthias

2015-01-01

The present study investigated whether developmental changes in cognitive control may underlie improvements of time-based prospective memory. Five-, 7-, 9-, and 11-year-olds (N = 166) completed a driving simulation task (ongoing task) in which they had to refuel their vehicle at specific points in time (PM task). The availability of cognitive control resources was experimentally manipulated by imposing a secondary task that required divided attention. Children completed the driving simulation task both in a full-attention condition and a divided-attention condition where they had to carry out a secondary task. Results revealed that older children performed better than younger children on the ongoing task and PM task. Children performed worse on the ongoing and PM tasks in the divided-attention condition compared to the full-attention condition. With respect to time monitoring in the final interval prior to the PM target, divided attention interacted with age such that older children's time monitoring was more negatively affected by the secondary task compared to younger children. Results are discussed in terms of developmental shifts from reactive to proactive monitoring strategies.

Recoding low-level simulator data into a record of meaningful task performance: the integrated task modeling environment (ITME).

PubMed

King, Robert; Parker, Simon; Mouzakis, Kon; Fletcher, Winston; Fitzgerald, Patrick

2007-11-01

The Integrated Task Modeling Environment (ITME) is a user-friendly software tool that has been developed to automatically recode low-level data into an empirical record of meaningful task performance. The present research investigated and validated the performance of the ITME software package by conducting complex simulation missions and comparing the task analyses produced by ITME with taskanalyses produced by experienced video analysts. A very high interrater reliability (> or = .94) existed between experienced video analysts and the ITME for the task analyses produced for each mission. The mean session time:analysis time ratio was 1:24 using video analysis techniques and 1:5 using the ITME. It was concluded that the ITME produced task analyses that were as reliable as those produced by experienced video analysts, and significantly reduced the time cost associated with these analyses.

Apollo 15 time and motion study

NASA Technical Reports Server (NTRS)

Kubis, J. F.; Elrod, J. T.; Rusnak, R.; Barnes, J. E.

1972-01-01

A time and motion study of Apollo 15 lunar surface activity led to examination of four distinct areas of crewmen activity. These areas are: an analysis of lunar mobility, a comparative analysis of tasks performed in 1-g training and lunar EVA, an analysis of the metabolic cost of two activities that are performed in several EVAs, and a fall/near-fall analysis. An analysis of mobility showed that the crewmen used three basic mobility patterns (modified walk, hop, side step) while on the lunar surface. These mobility patterns were utilized as adaptive modes to compensate for the uneven terrain and varied soil conditions that the crewmen encountered. A comparison of the time required to perform tasks at the final 1-g lunar EVA training sessions and the time required to perform the same task on the lunar surface indicates that, in almost all cases, it took significantly more time (on the order of 40%) to perform tasks on the moon. This increased time was observed even after extraneous factors (e.g., hardware difficulties) were factored out.

Maximal force and tremor changes across the menstrual cycle.

PubMed

Tenan, Matthew S; Hackney, Anthony C; Griffin, Lisa

2016-01-01

Sex hormones have profound effects on the nervous system in vitro and in vivo. The present study examines the effect of the menstrual cycle on maximal isometric force (MVC) and tremor during an endurance task. Nine eumenorrheic females participated in five study visits across their menstrual cycle. In each menstrual phase, an MVC and an endurance task to failure were performed. Tremor across the endurance task was quantified as the coefficient of variation in force and was assessed in absolute time and relative percent time to task failure. MVC decreases 23% from ovulation to the mid luteal phase of the menstrual cycle. In absolute time, the mid luteal phase has the highest initial tremor, though the early follicular phase has substantially higher tremor than other phases after 150 s of task performance. In relative time, the mid luteal phase has the highest level of tremor throughout the endurance task. Both MVC and tremor during an endurance task are modified by the menstrual cycle. Performance of tasks and sports which require high force and steadiness to exhaustion may be decreased in the mid luteal phase compared to other menstrual phases.

WHY DOES OLDER ADULTS' BALANCE BECOME LESS STABLE WHEN WALKING AND PERFORMING A SECONDARY TASK? EXAMINATION OF ATTENTIONAL SWITCHING ABILITIES

PubMed Central

Hawkes, Teresa D; Siu, Ka-Chun; Silsupadol, Patima; Woollacott, Marjorie H.

2011-01-01

Previous research using dual-task paradigms indicates balance-impaired older adults (BIOA) are less able to flexibly shift attentional focus between a cognitive and motor task than healthy older adults (HOA). Shifting attention is a component of executive function. Task switch tests assess executive attention function. This multivariate study asked if BIOAs demonstrate greater task switching deficits than HOAs. A group of 39 HOA (65–80 yrs) and BIOA (65–87 yrs) subjects performed a visuo-spatial task switch. A sub-group of subjects performed a dual-task obstacle avoidance paradigm. All participants completed the Berg Balance Scale (BBS) and Timed Up and Go (TUG). We assessed differences by group for: 1) visuo-spatial task switch reaction times (switch/no-switch), and performance on the BBS and TUG. Our balance groups differed significantly on BBS score (p < .001) and switch reaction time (p = .032), but not the TUG. This confirmed our hypothesis that neuromuscular and executive attention function differs between these two groups. For our BIOA sub-group, gait velocity correlated negatively with performance on the switch condition (p=.036). This suggests that BIOA efficiency of attentional allocation in dual task settings should be further explored. PMID:21964051

The hard fall effect: high working memory capacity leads to a higher, but less robust short-term memory performance.

PubMed

Thomassin, Noémylle; Gonthier, Corentin; Guerraz, Michel; Roulin, Jean-Luc

2015-01-01

Participants with a high working memory span tend to perform better than low spans in a variety of tasks. However, their performance is paradoxically more impaired when they have to perform two tasks at once, a phenomenon that could be labeled the "hard fall effect." The present study tested whether this effect exists in a short-term memory task, and investigated the proposal that the effect is due to high spans using efficient facilitative strategies under simple task conditions. Ninety-eight participants performed a spatial short-term memory task under simple and dual task conditions; stimuli presentation times either allowed for the use of complex facilitative strategies or not. High spans outperformed low spans only under simple task conditions when presentation times allowed for the use of facilitative strategies. These results indicate that the hard fall effect exists on a short-term memory task and may be caused by individual differences in strategy use.

Effects of reaction time variability and age on brain activity during Stroop task performance.

PubMed

Tam, Angela; Luedke, Angela C; Walsh, Jeremy J; Fernandez-Ruiz, Juan; Garcia, Angeles

2015-09-01

Variability in reaction time during task performance may reflect fluctuations in attention and cause reduced performance in goal-directed tasks, yet it is unclear whether the mechanisms behind this phenomenon change with age. Using fMRI, we tested young and cognitively healthy older adults with the Stroop task to determine whether aging affects the neural mechanisms underlying intra-individual reaction time variability. We found significant between-group differences in BOLD activity modulated by reaction time. In older adults, longer reaction times were associated with greater activity in frontoparietal attentional areas, while in younger adults longer reaction times were associated with greater activity in default mode network areas. Our results suggest that the neural correlates of reaction time variability change with healthy aging, reinforcing the concept of functional plasticity to maintain high cognitive function throughout the lifespan.

Time-on-task effects in children with and without ADHD: depletion of executive resources or depletion of motivation?

PubMed

Dekkers, Tycho J; Agelink van Rentergem, Joost A; Koole, Alette; van den Wildenberg, Wery P M; Popma, Arne; Bexkens, Anika; Stoffelsen, Reino; Diekmann, Anouk; Huizenga, Hilde M

2017-12-01

Children with attention-deficit/hyperactivity disorder (ADHD) are characterized by deficits in their executive functioning and motivation. In addition, these children are characterized by a decline in performance as time-on-task increases (i.e., time-on-task effects). However, it is unknown whether these time-on-task effects should be attributed to deficits in executive functioning or to deficits in motivation. Some studies in typically developing (TD) adults indicated that time-on-task effects should be interpreted as depletion of executive resources, but other studies suggested that they represent depletion of motivation. We, therefore, investigated, in children with and without ADHD, whether there were time-on-task effects on executive functions, such as inhibition and (in)attention, and whether these were best explained by depletion of executive resources or depletion of motivation. The stop-signal task (SST), which generates both indices of inhibition (stop-signal reaction time) and attention (reaction time variability and errors), was administered in 96 children (42 ADHD, 54 TD controls; aged 9-13). To differentiate between depletion of resources and depletion of motivation, the SST was administered twice. Half of the participants was reinforced during second task performance, potentially counteracting depletion of motivation. Multilevel analyses indicated that children with ADHD were more affected by time-on-task than controls on two measures of inattention, but not on inhibition. In the ADHD group, reinforcement only improved performance on one index of attention (i.e., reaction time variability). The current findings suggest that time-on-task effects in children with ADHD occur specifically in the attentional domain, and seem to originate in both depletion of executive resources and depletion of motivation. Clinical implications for diagnostics, psycho-education, and intervention are discussed.

Strategic workload management and decision biases in aviation

NASA Technical Reports Server (NTRS)

Raby, Mireille; Wickens, Christopher D.

1994-01-01

Thirty pilots flew three simulated landing approaches under conditions of low, medium, and high workload. Workload conditions were created by varying time pressure and external communications requirements. Our interest was in how the pilots strategically managed or adapted to the increasing workload. We independently assessed the pilot's ranking of the priority of different discrete tasks during the approach and landing. Pilots were found to sacrifice some aspects of primary flight control as workload increased. For discrete tasks, increasing workload increased the amount of time in performing the high priority tasks, decreased the time in performing those of lowest priority, and did not affect duration of performance episodes or optimality of scheduling of tasks of any priority level. Individual differences analysis revealed that high-performing subjects scheduled discrete tasks earlier in the flight and shifted more often between different activities.

The Effect of Task Duration on Event-Based Prospective Memory: A Multinomial Modeling Approach

PubMed Central

Zhang, Hongxia; Tang, Weihai; Liu, Xiping

2017-01-01

Remembering to perform an action when a specific event occurs is referred to as Event-Based Prospective Memory (EBPM). This study investigated how EBPM performance is affected by task duration by having university students (n = 223) perform an EBPM task that was embedded within an ongoing computer-based color-matching task. For this experiment, we separated the overall task’s duration into the filler task duration and the ongoing task duration. The filler task duration is the length of time between the intention and the beginning of the ongoing task, and the ongoing task duration is the length of time between the beginning of the ongoing task and the appearance of the first Prospective Memory (PM) cue. The filler task duration and ongoing task duration were further divided into three levels: 3, 6, and 9 min. Two factors were then orthogonally manipulated between-subjects using a multinomial processing tree model to separate the effects of different task durations on the two EBPM components. A mediation model was then created to verify whether task duration influences EBPM via self-reminding or discrimination. The results reveal three points. (1) Lengthening the duration of ongoing tasks had a negative effect on EBPM performance while lengthening the duration of the filler task had no significant effect on it. (2) As the filler task was lengthened, both the prospective and retrospective components show a decreasing and then increasing trend. Also, when the ongoing task duration was lengthened, the prospective component decreased while the retrospective component significantly increased. (3) The mediating effect of discrimination between the task duration and EBPM performance was significant. We concluded that different task durations influence EBPM performance through different components with discrimination being the mediator between task duration and EBPM performance. PMID:29163277

Mitigating the effects of in-vehicle distractions through use of the Psychological Refractory Period paradigm.

PubMed

Hibberd, Daryl L; Jamson, Samantha L; Carsten, Oliver M J

2013-01-01

Modern driving involves frequent and potentially detrimental interactions with distracting in-vehicle tasks. Distraction has been shown to slow brake reaction time and decrease lateral and longitudinal vehicle control. It is likely that these negative effects will become more prevalent in the future as advances are made in the functionality, availability, and number of in-vehicle systems. This paper addresses this problem by considering ways to manage in-vehicle task presentation to mitigate their distracting effects. A driving simulator experiment using 48 participants was performed to investigate the existence of the Psychological Refractory Period in the driving context and its effect on braking performance. Drivers were exposed to lead vehicle braking events in isolation (single-task) and with a preceding surrogate in-vehicle task (dual-task). In dual-task scenarios, the time interval between the in-vehicle and braking tasks was manipulated. Brake reaction time increased when drivers were distracted. The in-vehicle task interfered with the performance of the braking task in a manner that was dependent on the interval between the two tasks, with slower reactions following a shorter inter-task interval. This is the Psychological Refractory Period effect. These results have implications for driver safety during in-vehicle distraction. The findings are used to develop recommendations regarding the timing of in-vehicle task presentation so as to reduce their potentially damaging effects on braking performance. In future, these guidelines could be incorporated into a driver workload management system to minimise the opportunity for a driver to be distracted from the ongoing driving task. Copyright © 2012 Elsevier Ltd. All rights reserved.

Dynamic postural control and associated attentional demands in contemporary dancers versus non-dancers

PubMed Central

Sirois-Leclerc, Geneviève; Remaud, Anthony

2017-01-01

Postural control is not a fully automatic process, but requires a certain level of attention, particularly as the difficulty of the postural task increases. This study aimed at testing whether experienced contemporary dancers, because of their specialized training involving the control of posture/balance, would present with a dual-task performance suggesting lesser attentional demands associated with dynamic postural control compared with non-dancers. Twenty dancers and 16 non-dancers performed a dynamic postural tracking task in both antero-posterior and side-to-side directions, while standing on a force platform. The postural task was performed, in turn, 1) as a stand-alone task, and concurrently with both 2) a simple reaction time task and 3) a choice reaction time task. Postural control performance was estimated through variables calculated from centre of pressure movements. Although no overall group difference was found in reaction time values, we found a better ability to control the side to side movements of the centre of pressure during the tracking task in dancers compared with non-dancers, which was dependent on the secondary task. This suggests that such increased ability is influenced by available attentional resources. PMID:28323843

Dynamic postural control and associated attentional demands in contemporary dancers versus non-dancers.

PubMed

Sirois-Leclerc, Geneviève; Remaud, Anthony; Bilodeau, Martin

2017-01-01

Postural control is not a fully automatic process, but requires a certain level of attention, particularly as the difficulty of the postural task increases. This study aimed at testing whether experienced contemporary dancers, because of their specialized training involving the control of posture/balance, would present with a dual-task performance suggesting lesser attentional demands associated with dynamic postural control compared with non-dancers. Twenty dancers and 16 non-dancers performed a dynamic postural tracking task in both antero-posterior and side-to-side directions, while standing on a force platform. The postural task was performed, in turn, 1) as a stand-alone task, and concurrently with both 2) a simple reaction time task and 3) a choice reaction time task. Postural control performance was estimated through variables calculated from centre of pressure movements. Although no overall group difference was found in reaction time values, we found a better ability to control the side to side movements of the centre of pressure during the tracking task in dancers compared with non-dancers, which was dependent on the secondary task. This suggests that such increased ability is influenced by available attentional resources.

Recalibration of the Multisensory Temporal Window of Integration Results from Changing Task Demands

PubMed Central

Mégevand, Pierre; Molholm, Sophie; Nayak, Ashabari; Foxe, John J.

2013-01-01

The notion of the temporal window of integration, when applied in a multisensory context, refers to the breadth of the interval across which the brain perceives two stimuli from different sensory modalities as synchronous. It maintains a unitary perception of multisensory events despite physical and biophysical timing differences between the senses. The boundaries of the window can be influenced by attention and past sensory experience. Here we examined whether task demands could also influence the multisensory temporal window of integration. We varied the stimulus onset asynchrony between simple, short-lasting auditory and visual stimuli while participants performed two tasks in separate blocks: a temporal order judgment task that required the discrimination of subtle auditory-visual asynchronies, and a reaction time task to the first incoming stimulus irrespective of its sensory modality. We defined the temporal window of integration as the range of stimulus onset asynchronies where performance was below 75% in the temporal order judgment task, as well as the range of stimulus onset asynchronies where responses showed multisensory facilitation (race model violation) in the reaction time task. In 5 of 11 participants, we observed audio-visual stimulus onset asynchronies where reaction time was significantly accelerated (indicating successful integration in this task) while performance was accurate in the temporal order judgment task (indicating successful segregation in that task). This dissociation suggests that in some participants, the boundaries of the temporal window of integration can adaptively recalibrate in order to optimize performance according to specific task demands. PMID:23951203

Force-reflection and shared compliant control in operating telemanipulators with time delay

NASA Technical Reports Server (NTRS)

Kim, Won S.; Hannaford, Blake; Bejczy, Antal K.

1992-01-01

The performance of an advanced telemanipulation system in the presence of a wide range of time delays between a master control station and a slave robot is quantified. The contemplated applications include multiple satellite links to LEO, geosynchronous operation, spacecraft local area networks, and general-purpose computer-based short-distance designs. The results of high-precision peg-in-hole tasks performed by six test operators indicate that task performance decreased linearly with introduced time delays for both kinesthetic force feedback (KFF) and shared compliant control (SCC). The rate of this decrease was substantially improved with SCC compared to KFF. Task performance at delays above 1 s was not possible using KFF. SCC enabled task performance for such delays, which are realistic values for ground-controlled remote manipulation of telerobots in space.

How Changes in White Matter Might Underlie Improved Reaction Time Due to Practice1

PubMed Central

Voelker, Pascale; Piscopo, Denise; Weible, Aldis; Lynch, Gary; Rothbart, Mary K.; Posner, Michael I.; Niell, Cristopher M.

2017-01-01

Why does training on a task reduce the reaction time for performing it? New research points to changes in white matter pathways as one likely mechanism. These pathways connect remote brain areas involved in performing the task. Genetic variations may be involved in individual differences in the extent of this improvement. If white matter change is involved in improved reaction time with training, it may point the way toward understanding where and how generalization occurs. We examine the hypothesis that brain pathways shared by different tasks may result in improved performance of cognitive tasks remote from the training. PMID:27064751

Sleep to the beat: A nap favours consolidation of timing.

PubMed

Verweij, Ilse M; Onuki, Yoshiyuki; Van Someren, Eus J W; Van der Werf, Ysbrand D

2016-06-01

Growing evidence suggests that sleep is important for procedural learning, but few studies have investigated the effect of sleep on the temporal aspects of motor skill learning. We assessed the effect of a 90-min day-time nap on learning a motor timing task, using 2 adaptations of a serial interception sequence learning (SISL) task. Forty-two right-handed participants performed the task before and after a 90-min period of sleep or wake. Electroencephalography (EEG) was recorded throughout. The motor task consisted of a sequential spatial pattern and was performed according to 2 different timing conditions, that is, either following a sequential or a random temporal pattern. The increase in accuracy was compared between groups using a mixed linear regression model. Within the sleep group, performance improvement was modeled based on sleep characteristics, including spindle- and slow-wave density. The sleep group, but not the wake group, showed improvement in the random temporal, but especially and significantly more strongly in the sequential temporal condition. None of the sleep characteristics predicted improvement on either general of the timing conditions. In conclusion, a daytime nap improves performance on a timing task. We show that performance on the task with a sequential timing sequence benefits more from sleep than motor timing. More important, the temporal sequence did not benefit initial learning, because differences arose only after an offline period and specifically when this period contained sleep. Sleep appears to aid in the extraction of regularities for optimal subsequent performance. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Context-Sensitive Adjustment of Cognitive Control in Dual-Task Performance

ERIC Educational Resources Information Center

Fischer, Rico; Gottschalk, Caroline; Dreisbach, Gesine

2014-01-01

Performing 2 highly similar tasks at the same time requires an adaptive regulation of cognitive control to shield prioritized primary task processing from between-task (cross-talk) interference caused by secondary task processing. In the present study, the authors investigated how implicitly and explicitly delivered information promotes the…

Evaluation of several secondary tasks in the determination of permissible time delays in simulator visual and motion cues

NASA Technical Reports Server (NTRS)

Miller, G. K., Jr.; Riley, D. R.

1978-01-01

The effect of secondary tasks in determining permissible time delays in visual-motion simulation of a pursuit tracking task was examined. A single subject, a single set of aircraft handling qualities, and a single motion condition in tracking a target aircraft that oscillates sinusoidally in altitude were used. In addition to the basic simulator delays the results indicate that the permissible time delay is about 250 msec for either a tapping task, an adding task, or an audio task and is approximately 125 msec less than when no secondary task is involved. The magnitudes of the primary task performance measures, however, differ only for the tapping task. A power spectraldensity analysis basically confirms the result by comparing the root-mean-square performance measures. For all three secondary tasks, the total pilot workload was quite high.

Dual-tasks and walking fast: relationship to extra-pyramidal signs in advanced Alzheimer disease.

PubMed

Camicioli, Richard; Bouchard, Thomas; Licis, Lisa

2006-10-25

Extra-pyramidal signs (EPS) and cadence predicted falls risk in patients with advanced Alzheimer disease (AD). Dual task performance predicts falls with variable success. Dual-task performance and walking fast were examined in advanced AD patients with EPS (EPS+, >3 modified Unified Parkinson's Disease Rating Scale [UPDRS] signs) or without EPS (EPS-, three or less UPDRS signs). Demographics, mental and functional status, behavioral impairment, EPS, and quantitative gait measures (GaitRite) were determined. The effects of an automatic dual-task (simple counting) and of walking fast on spatial and temporal gait characteristics were compared between EPS+ and EPS- subjects using a repeated measures design. Cadence decreased, while stride time, swing time and variability in swing time increased with the dual task. Results were insignificant after adjusting for secondary task performance. With walking fast, speed, cadence and stride length increased while stride time, swing time and double support time decreased. Although EPS+ subjects were slower and had decreased stride length, dual task and walking fast effects did not differ from EPS- subjects. Patient characteristics, the type of secondary task and the specific gait measures examined vary in the literature. In this moderately to severely demented population, EPS did not affect "unconscious" (dual task) or "conscious" (walking fast) gait modulation. Given their high falls risk, and retained ability to modulate walking, EPS+ AD patients may be ideal candidates for interventions aimed at preventing falls.

An evidence accumulation model for conflict detection performance in a simulated air traffic control task.

PubMed

Neal, Andrew; Kwantes, Peter J

2009-04-01

The aim of this article is to develop a formal model of conflict detection performance. Our model assumes that participants iteratively sample evidence regarding the state of the world and accumulate it over time. A decision is made when the evidence reaches a threshold that changes over time in response to the increasing urgency of the task. Two experiments were conducted to examine the effects of conflict geometry and timing on response proportions and response time. The model is able to predict the observed pattern of response times, including a nonmonotonic relationship between distance at point of closest approach and response time, as well as effects of angle of approach and relative velocity. The results demonstrate that evidence accumulation models provide a good account of performance on a conflict detection task. Evidence accumulation models are a form of dynamic signal detection theory, allowing for the analysis of response times as well as response proportions, and can be used for simulating human performance on dynamic decision tasks.

Quality of Learners' Time and Learning Performance beyond Quantitative Time-on-Task

ERIC Educational Resources Information Center

Romero, Margarida; Barbera, Elena

2011-01-01

Along with the amount of time spent learning (or time-on-task), the quality of learning time has a real influence on learning performance. Quality of time in online learning depends on students' time availability and their willingness to devote quality cognitive time to learning activities. However, the quantity and quality of the time spent by…

Sex differences in prefrontal hemodynamic response to mental arithmetic as assessed by near-infrared spectroscopy.

PubMed

Yang, Hongyu; Wang, Ying; Zhou, Zhenyu; Gong, Hui; Luo, Qingming; Wang, Yiwen; Lu, Zuhong

2009-12-01

Sex differences in cognitive tasks have been widely investigated. With brain-imaging techniques, the functions of the brain during the performance of tasks can be examined. Mental arithmetic and near-infrared spectroscopy (NIRS) were used to assess sex differences in prefrontal area activation in a functional brain study. Healthy college students were recruited to perform 2 mental arithmetic tasks. In the first (easy) task, students had to subtract a 1-digit number from a 3-digit number. In the second (difficult) task, they had to subtract a 2-digit number from a 3-digit number. Changes in the concentration of oxygenated hemoglobin (oxy-Hgb) in the prefrontal area during the tasks were measured with NIRS. Thirty students (15 men, 15 women; mean [SD] age: 24.9 [2.2] and 24.3 [2.6] years, respectively) were recruited from Southeast University, Nanjing, China, to participate in the study. The concentration of oxy-Hgb increased during both mental arithmetic tasks (difficult task vs easy task, mean [SD] % arbitrary units: 4.36 [4.38] vs 2.26 [2.82]; F(1,28) = 222.80; P < 0.01). Significant interactions of task x sex (F(1,28) = 82.95), time x sex (F(1,28) = 34.48), task x time (F(1,28) = 222.57), and task x time x sex (F(1,28) = 83.09) were obtained (all, P < 0.01). However, for the 2 tasks, no significant differences between men and women were observed in the mean (SD) response time (men vs women, sec: 3.60 [0.74] vs 3.56 [0.49] for the easy task, 6.55 [0.77] vs 6.44 [0.75] for the difficult task; F(1,28) = 0.67; P = NS) or accuracy rate (men vs women, %: 95.33 [7.40] vs 92.77 [8.80] for the easy task, 62.67 [28.56] vs 54.67 [18.75] for the difficult task; F(1,28) = 0.54; P = NS). Male students showed neural efficiency (less prefrontal activation in subjects with better performance) during the difficult task. In these subjects, sex differences in prefrontal response when performing mental arithmetic were associated with the intensity of the task. Compared with men, women had greater efficiency in task performance (ie, less activation or oxygen consumption for equal performance). Copyright 2009 Excerpta Medica Inc. All rights reserved.

Why are You Late?: Investigating the Role of Time Management in Time-Based Prospective Memory

PubMed Central

Waldum, Emily R; McDaniel, Mark A.

2016-01-01

Time-based prospective memory tasks (TBPM) are those that are to be performed at a specific future time. Contrary to typical laboratory TBPM tasks (e.g., “hit the “z” key every 5 minutes”), many real-world TBPM tasks require more complex time-management processes. For instance to attend an appointment on time, one must estimate the duration of the drive to the appointment and then utilize this estimate to create and execute a secondary TBPM intention (e.g., “I need to start driving by 1:30 to make my 2:00 appointment on time”). Future under- and overestimates of drive time can lead to inefficient TBPM performance with the former lending to missed appointments and the latter to long stints in the waiting room. Despite the common occurrence of complex TBPM tasks in everyday life, to date, no studies have investigated how components of time management, including time estimation, affect behavior in such complex TBPM tasks. Therefore, the current study aimed to investigate timing biases in both older and younger adults and further to determine how such biases along with additional time management components including planning and plan fidelity influence complex TBPM performance. Results suggest for the first time that younger and older adults do not always utilize similar timing strategies, and as a result, can produce differential timing biases under the exact same environmental conditions. These timing biases, in turn, play a vital role in how efficiently both younger and older adults perform a later TBPM task that requires them to utilize their earlier time estimate. PMID:27336325

Correlates of stimulus-response congruence in the posterior parietal cortex.

PubMed

Stoet, Gijsbert; Snyder, Lawrence H

2007-02-01

Primate behavior is flexible: The response to a stimulus often depends on the task in which it occurs. Here we study how single neurons in the posterior parietal cortex (PPC) respond to stimuli which are associated with different responses in different tasks. Two rhesus monkeys performed a task-switching paradigm. Each trial started with a task cue instructing which of two tasks to perform, followed by a stimulus requiring a left or right button press. For half the stimuli, the associated responses were different in the two tasks, meaning that the task context was necessary to disambiguate the incongruent stimuli. The other half of stimuli required the same response irrespective of task context (congruent). Using this paradigm, we previously showed that behavioral responses to incongruent stimuli are significantly slower than to congruent stimuli. We now demonstrate a neural correlate in the PPC of the additional processing time required for incongruent stimuli. Furthermore, we previously found that 29% of parietal neurons encode the task being performed (task-selective cells). We now report differences in neuronal timing related to congruency in task-selective versus task nonselective cells. These differences in timing suggest that the activity in task nonselective cells reflects a motor command, whereas activity in task-selective cells reflects a decision process.

Studying Different Tasks of Implicit Learning across Multiple Test Sessions Conducted on the Web

PubMed Central

Sævland, Werner; Norman, Elisabeth

2016-01-01

Implicit learning is usually studied through individual performance on a single task, with the most common tasks being the Serial Reaction Time (SRT) task, the Dynamic System Control (DSC) task, and Artificial Grammar Learning (AGL). Few attempts have been made to compare performance across different implicit learning tasks within the same study. The current study was designed to explore the relationship between performance on the DSC Sugar factory task and the Alternating Serial Reaction Time (ASRT) task. We also addressed another limitation of traditional implicit learning experiments, namely that implicit learning is usually studied in laboratory settings over a restricted time span lasting for less than an hour. In everyday situations, implicit learning is assumed to involve a gradual accumulation of knowledge across several learning episodes over a longer time span. One way to increase the ecological validity of implicit learning experiments could be to present the learning material repeatedly across shorter test sessions. This can most easily be done by using a web-based setup in which participants can access the material from home. We therefore created an online web-based system for measuring implicit learning that could be administered in either single or multiple sessions. Participants (n = 66) were assigned to either a single session or a multiple session condition. Learning occurred on both tasks, and awareness measures suggested that acquired knowledge was not fully conscious on either of the tasks. Learning and the degree of conscious awareness of the learned regularities were compared across conditions and tasks. On the DSC task, performance was not affected by whether learning had taken place in one or over multiple sessions. On the ASRT task, RT improvement across blocks was larger in the multiple-session condition. Learning in the two tasks was not related. PMID:27375512

The effect of haptic guidance and visual feedback on learning a complex tennis task.

PubMed

Marchal-Crespo, Laura; van Raai, Mark; Rauter, Georg; Wolf, Peter; Riener, Robert

2013-11-01

While haptic guidance can improve ongoing performance of a motor task, several studies have found that it ultimately impairs motor learning. However, some recent studies suggest that the haptic demonstration of optimal timing, rather than movement magnitude, enhances learning in subjects trained with haptic guidance. Timing of an action plays a crucial role in the proper accomplishment of many motor skills, such as hitting a moving object (discrete timing task) or learning a velocity profile (time-critical tracking task). The aim of the present study is to evaluate which feedback conditions-visual or haptic guidance-optimize learning of the discrete and continuous elements of a timing task. The experiment consisted in performing a fast tennis forehand stroke in a virtual environment. A tendon-based parallel robot connected to the end of a racket was used to apply haptic guidance during training. In two different experiments, we evaluated which feedback condition was more adequate for learning: (1) a time-dependent discrete task-learning to start a tennis stroke and (2) a tracking task-learning to follow a velocity profile. The effect that the task difficulty and subject's initial skill level have on the selection of the optimal training condition was further evaluated. Results showed that the training condition that maximizes learning of the discrete time-dependent motor task depends on the subjects' initial skill level. Haptic guidance was especially suitable for less-skilled subjects and in especially difficult discrete tasks, while visual feedback seems to benefit more skilled subjects. Additionally, haptic guidance seemed to promote learning in a time-critical tracking task, while visual feedback tended to deteriorate the performance independently of the task difficulty and subjects' initial skill level. Haptic guidance outperformed visual feedback, although additional studies are needed to further analyze the effect of other types of feedback visualization on motor learning of time-critical tasks.

Tracking performance under time sharing conditions with a digit processing task: A feedback control theory analysis. [attention sharing effect on operator performance

NASA Technical Reports Server (NTRS)

Gopher, D.; Wickens, C. D.

1975-01-01

A one dimensional compensatory tracking task and a digit processing reaction time task were combined in a three phase experiment designed to investigate tracking performance in time sharing. Adaptive techniques, elaborate feedback devices, and on line standardization procedures were used to adjust task difficulty to the ability of each individual subject and manipulate time sharing demands. Feedback control analysis techniques were employed in the description of tracking performance. The experimental results show that when the dynamics of a system are constrained, in such a manner that man machine system stability is no longer a major concern of the operator, he tends to adopt a first order control describing function, even with tracking systems of higher order. Attention diversion to a concurrent task leads to an increase in remnant level, or nonlinear power. This decrease in linearity is reflected both in the output magnitude spectra of the subjects, and in the linear fit of the amplitude ratio functions.

The effects of aging on postural control and selective attention when stepping down while performing a concurrent auditory response task.

PubMed

Tsang, William W N; Lam, Nazca K Y; Lau, Kit N L; Leung, Harry C H; Tsang, Crystal M S; Lu, Xi

2013-12-01

To investigate the effects of aging on postural control and cognitive performance in single- and dual-tasking. A cross-sectional comparative design was conducted in a university motion analysis laboratory. Young adults (n = 30; age 21.9 ± 2.4 years) and older adults (n = 30; age 71.9 ± 6.4 years) were recruited. Postural control after stepping down was measured with and without performing a concurrent auditory response task. Measurement included: (1) reaction time and (2) error rate in performing the cognitive task; (3) total sway path and (4) total sway area after stepping down. Our findings showed that the older adults had significantly longer reaction times and higher error rates than the younger subjects in both the single-tasking and dual-tasking conditions. The older adults had significantly longer reaction times and higher error rates when dual-tasking compared with single-tasking, but the younger adults did not. The older adults demonstrated significantly less total sway path, but larger total sway area in single-leg stance after stepping down than the young adults. The older adults showed no significant change in total sway path and area between the dual-tasking and when compared with single-tasking conditions, while the younger adults showed significant decreases in sway. Older adults prioritize postural control by sacrificing cognitive performance when faced with dual-tasking.

The effects of using a portable music player on simulated driving performance and task-sharing strategies.

PubMed

Young, Kristie L; Mitsopoulos-Rubens, Eve; Rudin-Brown, Christina M; Lenné, Michael G

2012-07-01

This study examined the effects of performing scrollable music selection tasks using a portable music player (iPod Touch™) on simulated driving performance and task-sharing strategies, as evidenced through eye glance behaviour and secondary task performance. A total of 37 drivers (18-48 yrs) completed the PC-based MUARC Driver Distraction Test (DDT) while performing music selection tasks on an iPod Touch. Drivers' eye glance behaviour was examined using faceLAB eye tracking equipment. Results revealed that performing music search tasks while driving increased the amount of time that drivers spent with their eyes off the roadway and decreased their ability to maintain a constant lane position and time headway from a lead vehicle. There was also evidence, however, that drivers attempted to regulate their behaviour when distracted by decreasing their speed and taking a large number of short glances towards the device. Overall, results suggest that performing music search tasks while driving is problematic and steps to prohibit this activity should be taken. Copyright © 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.

The effects of interaction with the device described by procedural text on recall, true/false, and task performance.

PubMed

Diehl, V A; Mills, C B

1995-11-01

In two experiments, subjects interacted to different extents with relevant devices while reading two complex multistep procedural texts and were then tested with task performance time, true/false, and recall measures. While reading, subjects performed the task (read and do), saw the experimenter perform the task (read and see experimenter do), imagined doing the task (read and imagine), looked at the device while reading (read and see), or only read (read only). Van Dijk and Kintsch's (1983) text representation theory led to the prediction that exposure to the task device (in the read-and-do, read-and-see, and read-and-see-experimenter-do conditions) would lead to the development of a stronger situation model and therefore faster task performance, whereas the read-only and read-and-see conditions would lead to a better textbase, and therefore better performance on the true/false and recall tasks. Paivio's (1991) dual coding theory led to the opposite prediction for recall. The results supported the text representation theory with task performance and recall. The read-and-see condition produced consistently good performance on the true/false measure. Amount of text study time contributed to recall performance. These findings support the notion that information available while reading leads to differential development of representations in memory, which, in turn, causes differences in performance on various measures.

Next Generation Real-Time Systems: Investigating the Potential of Partial-Solution Tasks.

DTIC Science & Technology

1994-12-01

insufficient for dealing with the complexities of next-generation real - time systems . New methods of intelligent control must be developed for guaranteeing...on-time task completion for real - time systems that are faced with unpredictable and dynamically changing requirements. Implementing real-time...tasks by experimentally measuring the change in performance of 11 simulated real - time systems when converted from all-or-nothing tasks to partial

Individual differences in implicit motor learning: task specificity in sensorimotor adaptation and sequence learning

PubMed Central

Raza, Meher; Ivry, Richard B.

2016-01-01

In standard taxonomies, motor skills are typically treated as representative of implicit or procedural memory. We examined two emblematic tasks of implicit motor learning, sensorimotor adaptation and sequence learning, asking whether individual differences in learning are correlated between these tasks, as well as how individual differences within each task are related to different performance variables. As a prerequisite, it was essential to establish the reliability of learning measures for each task. Participants were tested twice on a visuomotor adaptation task and on a sequence learning task, either the serial reaction time task or the alternating reaction time task. Learning was evident in all tasks at the group level and reliable at the individual level in visuomotor adaptation and the alternating reaction time task but not in the serial reaction time task. Performance variability was predictive of learning in both domains, yet the relationship was in the opposite direction for adaptation and sequence learning. For the former, faster learning was associated with lower variability, consistent with models of sensorimotor adaptation in which learning rates are sensitive to noise. For the latter, greater learning was associated with higher variability and slower reaction times, factors that may facilitate the spread of activation required to form predictive, sequential associations. Interestingly, learning measures of the different tasks were not correlated. Together, these results oppose a shared process for implicit learning in sensorimotor adaptation and sequence learning and provide insight into the factors that account for individual differences in learning within each task domain. NEW & NOTEWORTHY We investigated individual differences in the ability to implicitly learn motor skills. As a prerequisite, we assessed whether individual differences were reliable across test sessions. We found that two commonly used tasks of implicit learning, visuomotor adaptation and the alternating serial reaction time task, exhibited good test-retest reliability in measures of learning and performance. However, the learning measures did not correlate between the two tasks, arguing against a shared process for implicit motor learning. PMID:27832611

Effects of the Addition of a Dual Task to a Supervised Physical Exercise Program on Older Adults' Cognitive Performance.

PubMed

Ansai, Juliana Hotta; de Andrade, Larissa Pires; de Souza Buto, Marcele Stephanie; de Vassimon Barroso, Verena; Farche, Ana Claudia Silva; Rossi, Paulo Giusti; de Medeiros Takahashi, Anielle Cristhine

2017-04-01

The purpose of this study was to investigate the effects of the addition of a dual task to multicomponent training on cognition of active older adults. Eighty physically active older adults were divided into an intervention group (IG) and a control group (CG). Both groups performed multicomponent training over 12 weeks. The IG simultaneously performed exercises and cognitive tasks. The Mini-Mental State Examination, the Montreal Cognitive Assessment, and the Clock Drawing Test were used for cognitive assessments. The Timed Up and Go Test associated with a cognitive task was used for dual-task assessment. Significant interactions were not observed between groups in terms of the cognitive variables or the dual-task performance. An interaction was observed only for Timed Up and Go Test performance, which was better in the CG than in the IG. Active older adults showed no improvement in cognition following the addition of the dual task to the multicomponent training.

The Effect of N-3 on N-2 Repetition Costs in Task Switching

ERIC Educational Resources Information Center

Schuch, Stefanie; Grange, James A.

2015-01-01

N-2 task repetition cost is a response time and error cost returning to a task recently performed after one intervening trial (i.e., an ABA task sequence) compared with returning to a task not recently performed (i.e., a CBA task sequence). This cost is considered a robust measure of inhibitory control during task switching. The present article…

Blue-Enriched Light Enhances Alertness but Impairs Accurate Performance in Evening Chronotypes Driving in the Morning.

PubMed

Rodríguez-Morilla, Beatriz; Madrid, Juan A; Molina, Enrique; Pérez-Navarro, José; Correa, Ángel

2018-01-01

Attention maintenance is highly demanding and typically leads to vigilance decrement along time on task. Therefore, performance in tasks involving vigilance maintenance for long periods, such as driving, tends to deteriorate over time. Cognitive performance has been demonstrated to fluctuate over 24 h of the day (known as circadian oscillations), thus showing peaks and troughs depending on the time of day (leading to optimal and suboptimal times of day, respectively). Consequently, vigilance decrements are more pronounced along time on task when it is performed at suboptimal times of day. According to research, light exposure (especially blue-enriched white) enhances alertness. Thus, it has been proposed to prevent the vigilance decrement under such adverse circumstances. We aimed to explore the effects of blue-enriched white light (vs. dim light) on the performance of a simulated driving task at a suboptimal time of day. A group of evening-types was tested at 8 am, as this chronotype had previously shown their largest vigilance decrement at that time. In the dim light condition, vigilance decrements were expected on both subjective (as increments in the Karolinska Sleepiness Scale scores) and behavioral measures [as slower reaction times (RTs) in the auditory Psychomotor Vigilance Task, slower RTs to unexpected events during driving, and deteriorated driving accuracy along time on task]. Physiological activation was expected to decrease (as indexed by an increase of the distal-proximal temperature gradient, DPG). Under blue-enriched white light, all these trends should be attenuated. Results from the control dim light condition replicated the vigilance decrement in all measures. Most important, the blue-enriched white light attenuated this decrement, leading to both lower DPG and faster RTs. However, it impaired accuracy of driving performance, and did not have any effect on subjective sleepiness. We conclude that exposure to blue-enriched light provides an effective countermeasure to enhance vigilance performance at suboptimal times of day, according to measures such as RTs. However, it should be considered that alerting effects of light could impair accuracy in precision tasks as keeping a proper car position. The current findings provide ergonomic implications for safety and fatigue related management systems.

Color temperature’s impact on task performance and brainwaves of school-age children

PubMed Central

Park, YunHee

2015-01-01

[Purpose] This study investigated color temperature’s impact on task performance. It presents a scientific analysis of brainwave and task performance time changes, and the results of a self-report type survey. [Subjects] Twenty-four elementary school fifth-grade boys and girls with no visual problems participated in the experiment. [Methods] Physiological reaction times of task performance were measured in a laboratory that could fix and maintain color temperature. Brainwave changes and the task performance times were measured, and a self-report questionnaire was conducted in order to measure of emotional reactions. [Results] Regarding the brainwave changes associated with color temperature, alpha waves were emitted in the O2 area when puzzle tasks were illuminated by orange light and low and high beta waves were emitted in the F3 area under white light. Five items (Brilliant, Soft, Lively, Relaxed, Open) were reported predominantly in responses to orange light in the self-report questionnaire. [Conclusion] The results of this study show that relaxation and stability are not assured when the color temperature is low, and that concentration and cognitive activity are not necessarily easier when the color temperature is high. The color temperature change when performing tasks promoted emotional factors more than brainwave, a biological change. PMID:26644662

Color temperature's impact on task performance and brainwaves of school-age children.

PubMed

Park, YunHee

2015-10-01

[Purpose] This study investigated color temperature's impact on task performance. It presents a scientific analysis of brainwave and task performance time changes, and the results of a self-report type survey. [Subjects] Twenty-four elementary school fifth-grade boys and girls with no visual problems participated in the experiment. [Methods] Physiological reaction times of task performance were measured in a laboratory that could fix and maintain color temperature. Brainwave changes and the task performance times were measured, and a self-report questionnaire was conducted in order to measure of emotional reactions. [Results] Regarding the brainwave changes associated with color temperature, alpha waves were emitted in the O2 area when puzzle tasks were illuminated by orange light and low and high beta waves were emitted in the F3 area under white light. Five items (Brilliant, Soft, Lively, Relaxed, Open) were reported predominantly in responses to orange light in the self-report questionnaire. [Conclusion] The results of this study show that relaxation and stability are not assured when the color temperature is low, and that concentration and cognitive activity are not necessarily easier when the color temperature is high. The color temperature change when performing tasks promoted emotional factors more than brainwave, a biological change.

Age-Related Differences in Reaction Time Task Performance in Young Children

ERIC Educational Resources Information Center

Kiselev, Sergey; Espy, Kimberlay Andrews; Sheffield, Tiffany

2009-01-01

Performance of reaction time (RT) tasks was investigated in young children and adults to test the hypothesis that age-related differences in processing speed supersede a "global" mechanism and are a function of specific differences in task demands and processing requirements. The sample consisted of 54 4-year-olds, 53 5-year-olds, 59…

Analysis of Time-on-Task, Behavior Experiences, and Performance in Two Online Courses with Different Authentic Learning Tasks

ERIC Educational Resources Information Center

Park, Sanghoon

2017-01-01

This paper reports the findings of a comparative analysis of online learner behavioral interactions, time-on-task, attendance, and performance at different points throughout a semester (beginning, during, and end) based on two online courses: one course offering authentic discussion-based learning activities and the other course offering authentic…

The Endurance of Children's Working Memory: A Recall Time Analysis

ERIC Educational Resources Information Center

Towse, John N.; Hitch, Graham J.; Hamilton, Z.; Pirrie, Sarah

2008-01-01

We analyze the timing of recall as a source of information about children's performance in complex working memory tasks. A group of 8-year-olds performed a traditional operation span task in which sequence length increased across trials and an operation period task in which processing requirements were extended across trials of constant sequence…

The role of memory representation in the vigilance decrement.

PubMed

Caggiano, Daniel M; Parasuraman, Raja

2004-10-01

Working memory load is critically important for the overall level of performance on vigilance tasks. However, its role in a key aspect of vigilance-sensitivity decrement over time-is unclear. We used a dual-task procedure in which either a spatial or a nonspatial working memory task was performed simultaneously with a spatial vigilance task for 20 min. Sensitivity in the vigilance task declined over time when the concurrent task involved spatial working memory. In contrast, there was no sensitivity decrement with a nonspatial working memory task. The results provide the first evidence of a specific role for working memory representation in vigilance decrement. The findings are also consistent with a multiple resource theory in which separate resources for memory representation and cognitive control operations are differentially susceptible to depletion over time, depending on the demands of the task at hand.

Working Memory Training Improves Dual-Task Performance on Motor Tasks.

PubMed

Kimura, Takehide; Kaneko, Fuminari; Nagahata, Keita; Shibata, Eriko; Aoki, Nobuhiro

2017-01-01

The authors investigated whether working memory training improves motor-motor dual-task performance consisted of upper and lower limb tasks. The upper limb task was a simple reaction task and the lower limb task was an isometric knee extension task. 45 participants (age = 21.8 ± 1.6 years) were classified into a working memory training group (WM-TRG), dual-task training group, or control group. The training duration was 2 weeks (15 min, 4 times/week). Our results indicated that working memory capacity increased significantly only in the WM-TRG. Dual-task performance improved in the WM-TRG and dual-task training group. Our study provides the novel insight that working memory training improves dual-task performance without specific training on the target motor task.

Does a multicomponent exercise program improve dual-task performance in amnestic mild cognitive impairment? A randomized controlled trial.

PubMed

Makizako, Hyuma; Doi, Takehiko; Shimada, Hiroyuki; Yoshida, Daisuke; Tsutsumimoto, Kota; Uemura, Kazuki; Suzuki, Takao

2012-12-01

There has been much interest in exercise interventions as a primary behavioral prevention strategy against cognitive decline. The aim of this study was to evaluate the effect of a multicomponent exercise program on physical and dual-task performances in community-dwelling older adults with amnestic mild cognitive impairment (aMCI). Fifty older adults (23 women) with aMCI (mean age, 76 years) were randomized to an intervention (n=25) or a control group (n=25). The intervention group received a multicomponent exercise program for 90 minutes/day, 2 days/week, or 40 times over six months. The multicomponent exercises included aerobic exercise, muscle strength training and postural balance retraining, which was conducted under multi-task conditions to stimulate attention and memory. Participants in the control group attended two health promotion education classes within six months. Physical and dual-task performances were measured before randomization and after six months. Dual-task performances using reaction times with balance and cognitive demands were measured. The improvement effects on dual-task performances with both balance and cognitive demands were not statistically significant: reaction time with balance demand F1,45=3.3, p=0.07, and cognitive demand F1,45=2.6, p=0.12. However, there was a significant group-by-time interaction on maximal walking speed, which decreased significantly in the control group (F1,45=5.9, p=0.02). This six-month multicomponent exercise program improved maximal walking speed in older adults with aMCI; however, it did not improve dual-task performances assessed by reaction times.

Between-Trial Forgetting Due to Interference and Time in Motor Adaptation.

PubMed

Kim, Sungshin; Oh, Youngmin; Schweighofer, Nicolas

2015-01-01

Learning a motor task with temporally spaced presentations or with other tasks intermixed between presentations reduces performance during training, but can enhance retention post training. These two effects are known as the spacing and contextual interference effect, respectively. Here, we aimed at testing a unifying hypothesis of the spacing and contextual interference effects in visuomotor adaptation, according to which forgetting between trials due to either spaced presentations or interference by another task will promote between-trial forgetting, which will depress performance during acquisition, but will promote retention. We first performed an experiment with three visuomotor adaptation conditions: a short inter-trial-interval (ITI) condition (SHORT-ITI); a long ITI condition (LONG-ITI); and an alternating condition with two alternated opposite tasks (ALT), with the same single-task ITI as in LONG-ITI. In the SHORT-ITI condition, there was fastest increase in performance during training and largest immediate forgetting in the retention tests. In contrast, in the ALT condition, there was slowest increase in performance during training and little immediate forgetting in the retention tests. Compared to these two conditions, in the LONG-ITI, we found intermediate increase in performance during training and intermediate immediate forgetting. To account for these results, we fitted to the data six possible adaptation models with one or two time scales, and with interference in the fast, or in the slow, or in both time scales. Model comparison confirmed that two time scales and some degree of interferences in either time scale are needed to account for our experimental results. In summary, our results suggest that retention following adaptation is modulated by the degree of between-trial forgetting, which is due to time-based decay in single adaptation task and interferences in multiple adaptation tasks.

The Use of Cognitive Cues for Anticipatory Strategies in a Dynamic Postural Control Task - Validation of a Novel Approach to Dual-Task Testing.

PubMed

Laessoe, Uffe; Grarup, Bo; Bangshaab, Jette

2016-01-01

Dual-task testing is relevant in the assessment of postural control. A combination of a primary (motor) and a secondary (distracting cognitive) tasks is most often used. It remains a challenge however, to standardize and monitor the cognitive task. In this study a new dual-task testing approach with a facilitating, rather than distracting, cognitive component was evaluated. Thirty-one community-dwelling elderly and fifteen young people were tested with respect to their ability to use anticipatory postural control strategies. The motor task consisted of twenty-five repetitive tasks in which the participants needed to exceed their limit of stability in order to touch one out of eight lights. The participants performed three tests. In two of the tests the color cues of the lights allowed the participants to utilize cognitive strategies to plan their next movement and improve their performance time. The young performed the baseline motor task test in an average of 29 seconds, while the average time for the elderly was 44 seconds. When comparing the performance time with a leading cue to the time with no cue, the young group improved their performance time significantly better than the elderly did: young: 17% (5), elderly: 5% (8); p<0.001. Similar differences were seen with a more complicated leading cue: young: 12% (5), elderly: 4% (9); p<0.01. The reliability of the test showed moderate to substantial agreement (ICC = 0.74), with a small learning effect between two sessions. The dual-task test was sensitive enough to discriminate between elderly and young people. It revealed that the elderly did not utilize cognitive cues for their anticipatory postural control strategies as well as the young were able to. The test procedure was feasible and comprehensible for the participants, and it may be relevant to standardize a similar test for an alternative dual-task approach in the clinical setting.

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 Fatigue Influences Time-On-Task during Bodyweight Resistance Training Exercise

PubMed Central

Head, James R.; Tenan, Matthew S.; Tweedell, Andrew J.; Price, Thomas F.; LaFiandra, Michael E.; Helton, William S.

2016-01-01

Prior investigations have shown measurable performance impairments on continuous physical performance tasks when preceded by a cognitively fatiguing task. However, the effect of cognitive fatigue on bodyweight resistance training exercise task performance is unknown. In the current investigation 18 amateur athletes completed a full body exercise task preceded by either a cognitive fatiguing or control intervention. In a randomized repeated measure design, each participant completed the same exercise task preceded by a 52 min cognitively fatiguing intervention (vigilance) or control intervention (video). Data collection sessions were separated by 1 week. Participants rated the fatigue intervention with a significantly higher workload compared to the control intervention (p < 0.001). Additionally, participants self-reported significantly greater energetic arousal for cognitively fatiguing task (p = 0.02). Cognitive fatigue did not significantly impact number of repetitions completed during the exercise task (p = 0.77); however, when cognitively fatigued, participants had decreased percent time-on-task (57%) relative to the no fatigue condition (60%; p = 0.04). RPE significantly changed over time (p < 0.001), but failed to show significant differences between the cognitive fatigue intervention and control intervention (p > 0.05). There was no statistical difference for heart rate or metabolic expenditure as a function of fatigue intervention during exercise. Cognitively fatigued athletes have decreased time-on-task in bodyweight resistance training exercise tasks. PMID:27635122

Electrophysiological indices of anterior cingulate cortex function reveal changing levels of cognitive effort and reward valuation that sustain task performance.

PubMed

Umemoto, Akina; Inzlicht, Michael; Holroyd, Clay B

2018-06-21

Successful execution of goal-directed behaviors often requires the deployment of cognitive control, which is thought to require cognitive effort. Recent theories have proposed that anterior cingulate cortex (ACC) regulates control levels by weighing the reward-related benefits of control against its effort-related costs. However, given that the sensations of cognitive effort and reward valuation are available only to introspection, this hypothesis is difficult to investigate empirically. We have proposed that two electrophysiological indices of ACC function, frontal midline theta and the reward positivity (RewP), provide objective measures of these functions. To explore this issue, we recorded the electroencephalogram (EEG) from participants engaged in an extended, cognitively-demanding task. Participants performed a time estimation task for 2 h in which they received reward and error feedback according to their task performance. We observed that the amplitude of the RewP, a feedback-locked component of the event related brain potential associated with reward processing, decreased with time-on-task. Conversely, frontal midline theta power, which consists of 4-8 Hz EEG oscillations associated with cognitive effort, increased with time-on-task. We also explored how these phenomena changed over time by conducting within-participant multi-level modeling analyses. Our results suggest that extended execution of a cognitively-demanding task is characterized by an early phase in which high control levels foster rapid improvements in task performance, and a later phase in which high control levels were necessary to maintain stable task performance, perhaps counteracting waning reward valuation. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Verification Method of Inter-Task Cooperation in Embedded Real-time Systems and its Evaluation

NASA Astrophysics Data System (ADS)

Yoshida, Toshio

In software development process of embedded real-time systems, the design of the task cooperation process is very important. The cooperating process of such tasks is specified by task cooperation patterns. Adoption of unsuitable task cooperation patterns has fatal influence on system performance, quality, and extendibility. In order to prevent repetitive work caused by the shortage of task cooperation performance, it is necessary to verify task cooperation patterns in an early software development stage. However, it is very difficult to verify task cooperation patterns in an early software developing stage where task program codes are not completed yet. Therefore, we propose a verification method using task skeleton program codes and a real-time kernel that has a function of recording all events during software execution such as system calls issued by task program codes, external interrupts, and timer interrupt. In order to evaluate the proposed verification method, we applied it to the software development process of a mechatronics control system.

Development and Testing of a Smartphone-Based Cognitive/Neuropsychological Evaluation System for Substance Abusers.

PubMed

Pal, Reshmi; Mendelson, John; Clavier, Odile; Baggott, Mathew J; Coyle, Jeremy; Galloway, Gantt P

2016-01-01

In methamphetamine (MA) users, drug-induced neurocognitive deficits may help to determine treatment, monitor adherence, and predict relapse. To measure these relationships, we developed an iPhone app (Neurophone) to compare lab and field performance of N-Back, Stop Signal, and Stroop tasks that are sensitive to MA-induced deficits. Twenty healthy controls and 16 MA-dependent participants performed the tasks in-lab using a validated computerized platform and the Neurophone before taking the latter home and performing the tasks twice daily for two weeks. N-Back task: there were no clear differences in performance between computer-based vs. phone-based in-lab tests and phone-based in-lab vs. phone-based in-field tests. Stop-Signal task: difference in parameters prevented comparison of computer-based and phone-based versions. There was significant difference in phone performance between field and lab. Stroop task: response time measured by the speech recognition engine lacked precision to yield quantifiable results. There was no learning effect over time. On an average, each participant completed 84.3% of the in-field NBack tasks and 90.4% of the in-field Stop Signal tasks (MA-dependent participants: 74.8% and 84.3%; healthy controls: 91.4% and 95.0%, respectively). Participants rated Neurophone easy to use. Cognitive tasks performed in-field using Neurophone have the potential to yield results comparable to those obtained in a laboratory setting. Tasks need to be modified for use as the app's voice recognition system is not yet adequate for timed tests.

Estimating endogenous changes in task performance from EEG

PubMed Central

Touryan, Jon; Apker, Gregory; Lance, Brent J.; Kerick, Scott E.; Ries, Anthony J.; McDowell, Kaleb

2014-01-01

Brain wave activity is known to correlate with decrements in behavioral performance as individuals enter states of fatigue, boredom, or low alertness.Many BCI technologies are adversely affected by these changes in user state, limiting their application and constraining their use to relatively short temporal epochs where behavioral performance is likely to be stable. Incorporating a passive BCI that detects when the user is performing poorly at a primary task, and adapts accordingly may prove to increase overall user performance. Here, we explore the potential for extending an established method to generate continuous estimates of behavioral performance from ongoing neural activity; evaluating the extended method by applying it to the original task domain, simulated driving; and generalizing the method by applying it to a BCI-relevant perceptual discrimination task. Specifically, we used EEG log power spectra and sequential forward floating selection (SFFS) to estimate endogenous changes in behavior in both a simulated driving task and a perceptual discrimination task. For the driving task the average correlation coefficient between the actual and estimated lane deviation was 0.37 ± 0.22 (μ ± σ). For the perceptual discrimination task we generated estimates of accuracy, reaction time, and button press duration for each participant. The correlation coefficients between the actual and estimated behavior were similar for these three metrics (accuracy = 0.25 ± 0.37, reaction time = 0.33 ± 0.23, button press duration = 0.36 ± 0.30). These findings illustrate the potential for modeling time-on-task decrements in performance from concurrent measures of neural activity. PMID:24994968

Why are you late? Investigating the role of time management in time-based prospective memory.

PubMed

Waldum, Emily R; McDaniel, Mark A

2016-08-01

Time-based prospective memory tasks (TBPM) are those that are to be performed at a specific future time. Contrary to typical laboratory TBPM tasks (e.g., hit the Z key every 5 min), many real-world TBPM tasks require more complex time-management processes. For instance, to attend an appointment on time, one must estimate the duration of the drive to the appointment and then use this estimate to create and execute a secondary TBPM intention (e.g., "I need to start driving by 1:30 to make my 2:00 appointment on time"). Future under- and overestimates of drive time can lead to inefficient TBPM performance with the former lending to missed appointments and the latter to long stints in the waiting room. Despite the common occurrence of complex TBPM tasks in everyday life, to date, no studies have investigated how components of time management, including time estimation, affect behavior in such complex TBPM tasks. Therefore, the current study aimed to investigate timing biases in both older and younger adults and, further, to determine how such biases along with additional time management components including planning and plan fidelity influence complex TBPM performance. Results suggest for the first time that younger and older adults do not always utilize similar timing strategies, and as a result, can produce differential timing biases under the exact same environmental conditions. These timing biases, in turn, play a vital role in how efficiently both younger and older adults perform a later TBPM task that requires them to utilize their earlier time estimate. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Can a senior house officer's time be used more effectively?

PubMed

Mitchell, J; Hayhurst, C; Robinson, S M

2004-09-01

To determine the amount of time senior house officers (SHO) spent performing tasks that could be delegated to a technician or administrative assistant and therefore to quantify the expected benefit that could be obtained by employing such physicians' assistants (PA). SHOs working in the emergency department were observed for one week by pre-clinical students who had been trained to code and time each task performed by SHOs. Activity was grouped into four categories (clinical, technical, administrative, and other). Those activities in the technical and administrative categories were those we believed could be performed by a PA. The SHOs worked 430 hours in total, of which only 25 hours were not coded due to lack of an observer. Of the 405 hours observed 86.2% of time was accounted for by the various codes. The process of taking a history and examining patients accounted for an average of 22% of coded time. Writing the patient's notes accounted for an average of 20% of coded time. Discussion with relatives and patients accounted for 4.7% of coded time and performing procedures accounted for 5.2% of coded time. On average across all shifts, 15% of coded time was spent doing either technical or administrative tasks. In this department an average of 15% of coded SHOs working time was spent performing administrative and technical tasks, rising to 17% of coded time during a night shift. This is equivalent to an average time of 78 minutes per 10 hour shift/SHO. Most tasks included in these categories could be performed by PAs thus potentially decreasing patient waiting times, improving risk management, allowing doctors to spend more time with their patients, and possibly improving doctors' training.

Comparison of precision and speed in laparoscopic and robot-assisted surgical task performance.

PubMed

Zihni, Ahmed; Gerull, William D; Cavallo, Jaime A; Ge, Tianjia; Ray, Shuddhadeb; Chiu, Jason; Brunt, L Michael; Awad, Michael M

2018-03-01

Robotic platforms have the potential advantage of providing additional dexterity and precision to surgeons while performing complex laparoscopic tasks, especially for those in training. Few quantitative evaluations of surgical task performance comparing laparoscopic and robotic platforms among surgeons of varying experience levels have been done. We compared measures of quality and efficiency of Fundamentals of Laparoscopic Surgery task performance on these platforms in novices and experienced laparoscopic and robotic surgeons. Fourteen novices, 12 expert laparoscopic surgeons (>100 laparoscopic procedures performed, no robotics experience), and five expert robotic surgeons (>25 robotic procedures performed) performed three Fundamentals of Laparoscopic Surgery tasks on both laparoscopic and robotic platforms: peg transfer (PT), pattern cutting (PC), and intracorporeal suturing. All tasks were repeated three times by each subject on each platform in a randomized order. Mean completion times and mean errors per trial (EPT) were calculated for each task on both platforms. Results were compared using Student's t-test (P < 0.05 considered statistically significant). Among novices, greater errors were noted during laparoscopic PC (Lap 2.21 versus Robot 0.88 EPT, P < 0.001). Among expert laparoscopists, greater errors were noted during laparoscopic PT compared with robotic (PT: Lap 0.14 versus Robot 0.00 EPT, P = 0.04). Among expert robotic surgeons, greater errors were noted during laparoscopic PC compared with robotic (Lap 0.80 versus Robot 0.13 EPT, P = 0.02). Among expert laparoscopists, task performance was slower on the robotic platform compared with laparoscopy. In comparisons of expert laparoscopists performing tasks on the laparoscopic platform and expert robotic surgeons performing tasks on the robotic platform, expert robotic surgeons demonstrated fewer errors during the PC task (P = 0.009). Robotic assistance provided a reduction in errors at all experience levels for some laparoscopic tasks, but no benefit in the speed of task performance. Robotic assistance may provide some benefit in precision of surgical task performance. Copyright © 2017 Elsevier Inc. All rights reserved.

Performance improvements from imagery: evidence that internal visual imagery is superior to external visual imagery for slalom performance

PubMed Central

Callow, Nichola; Roberts, Ross; Hardy, Lew; Jiang, Dan; Edwards, Martin Gareth

2013-01-01

We report three experiments investigating the hypothesis that use of internal visual imagery (IVI) would be superior to external visual imagery (EVI) for the performance of different slalom-based motor tasks. In Experiment 1, three groups of participants (IVI, EVI, and a control group) performed a driving-simulation slalom task. The IVI group achieved significantly quicker lap times than EVI and the control group. In Experiment 2, participants performed a downhill running slalom task under both IVI and EVI conditions. Performance was again quickest in the IVI compared to EVI condition, with no differences in accuracy. Experiment 3 used the same group design as Experiment 1, but with participants performing a downhill ski-slalom task. Results revealed the IVI group to be significantly more accurate than the control group, with no significant differences in time taken to complete the task. These results support the beneficial effects of IVI for slalom-based tasks, and significantly advances our knowledge related to the differential effects of visual imagery perspectives on motor performance. PMID:24155710

Artificial time constraints on the Iowa Gambling Task: the effects on behavioural performance and subjective experience.

PubMed

Bowman, Caroline H; Evans, Cathryn E Y; Turnbull, Oliver H

2005-02-01

In the last decade, the Iowa Gambling Task (IGT) has become a widely employed neuropsychological research instrument for the investigation of executive function. The task has been employed in a wide range of formats, from 'manual' procedures to more recently introduced computerised versions. Computer-based formats often require that responses on the task should be artificially delayed by a number of seconds between trials to collect skin-conductance data. Participants, however, may become frustrated when they want to select from a particular deck in the time-limited versions--so that an unintended emotional experience of frustration might well disrupt a task presumed to be reliant on emotion-based learning. We investigated the effect of the various types of Iowa Gambling Task format on performance, using three types of task: the classic manual administration, with no time limitations; a computerised administration with a 6-s enforced delay; and a control computerised version which had no time constraints. We also evaluated the subjective experience of participants on each task. There were no significant differences in performance, between formats, in behavioural terms. Subjective experience measures on the task also showed consistent effects across all three formats-with substantial, and rapidly developing, awareness of which decks were 'good' and 'bad.'

Event-related potentials and secondary task performance during simulated driving.

PubMed

Wester, A E; Böcker, K B E; Volkerts, E R; Verster, J C; Kenemans, J L

2008-01-01

Inattention and distraction account for a substantial number of traffic accidents. Therefore, we examined the impact of secondary task performance (an auditory oddball task) on a primary driving task (lane keeping). Twenty healthy participants performed two 20-min tests in the Divided Attention Steering Simulator (DASS). The visual secondary task of the DASS was replaced by an auditory oddball task to allow recording of brain activity. The driving task and the secondary (distracting) oddball task were presented in isolation and simultaneously, to assess their mutual interference. In addition to performance measures (lane keeping in the primary driving task and reaction speed in the secondary oddball task), brain activity, i.e. event-related potentials (ERPs), was recorded. Performance parameters on the driving test and the secondary oddball task did not differ between performance in isolation and simultaneous performance. However, when both tasks were performed simultaneously, reaction time variability increased in the secondary oddball task. Analysis of brain activity indicated that ERP amplitude (P3a amplitude) related to the secondary task, was significantly reduced when the task was performed simultaneously with the driving test. This study shows that when performing a simple secondary task during driving, performance of the driving task and this secondary task are both unaffected. However, analysis of brain activity shows reduced cortical processing of irrelevant, potentially distracting stimuli from the secondary task during driving.

Cognitive performance under motor demands - On the influence of task difficulty and postural control.

PubMed

Liebherr, Magnus; Weiland-Breckle, Hanna; Grewe, Tanja; Schumacher, Petra B

2018-04-01

We often walk around when we have to think about something, but suddenly stop when we are confronted with a demanding cognitive task, such as calculating 1540*24. While previous neurophysiological research investigated cognitive and motor performance separately, findings that combine both are rare. To get a deeper understanding of the influence of motor demands as well as the difficulty of a simultaneously performed cognitive task, we investigated 20 healthy individuals. Participants performed two cognitive tasks with different levels of difficulty while sitting or standing on one leg. In addition to behavioral data, we recorded the electroencephalogram from 26Ag/AgCI scalp electrodes. The critical time-windows, predefined by visual inspection, yielded an early (200-300 ms, P2) and a subsequent positivity (350-500 ms, P3). Statistical analysis of the early time window registered a motor × cognition interaction. Resolution of this interaction revealed an effect of the cognitive task in the one-legged stance motor condition, with a more pronounced positivity for the difficult task. No significant differences between cognitive tasks emerged for the simple motor condition. The time-window between 350 and 500 ms registered main effects of the motor task and a trend for the cognitive task. While the influence of cognitive task difficulty (in the P3) is in accordance with previous studies, the motor task effect is specific to one-legged stance (cf. no effects for running in previous research). The motor-cognition interaction found in the P2 indicates that the more difficult motor task (one-legged stance) facilitates cognitive task performance. Copyright © 2018 Elsevier B.V. All rights reserved.

A Report on Applying EEGnet to Discriminate Human State Effects on Task Performance

DTIC Science & Technology

2018-01-01

whether we could identify what task the participant was performing from differences in the recorded brain time series . We modeled the relationship...between input data (brain time series ) and output labels (task A and task B) as an unknown function, and we found an optimal approximation of that...this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. Citation of

Immediate Effects of Clock-Turn Strategy on the Pattern and Performance of Narrow Turning in Persons With Parkinson Disease.

PubMed

Yang, Wen-Chieh; Hsu, Wei-Li; Wu, Ruey-Meei; Lin, Kwan-Hwa

2016-10-01

Turning difficulty is common in people with Parkinson disease (PD). The clock-turn strategy is a cognitive movement strategy to improve turning performance in people with PD despite its effects are unverified. Therefore, this study aimed to investigate the effects of the clock-turn strategy on the pattern of turning steps, turning performance, and freezing of gait during a narrow turning, and how these effects were influenced by concurrent performance of a cognitive task (dual task). Twenty-five people with PD were randomly assigned to the clock-turn or usual-turn group. Participants performed the Timed Up and Go test with and without concurrent cognitive task during the medication OFF period. The clock-turn group performed the Timed Up and Go test using the clock-turn strategy, whereas participants in the usual-turn group performed in their usual manner. Measurements were taken during the 180° turn of the Timed Up and Go test. The pattern of turning steps was evaluated by step time variability and step time asymmetry. Turning performance was evaluated by turning time and number of turning steps. The number and duration of freezing of gait were calculated by video review. The clock-turn group had lower step time variability and step time asymmetry than the usual-turn group. Furthermore, the clock-turn group turned faster with fewer freezing of gait episodes than the usual-turn group. Dual task increased the step time variability and step time asymmetry in both groups but did not affect turning performance and freezing severity. The clock-turn strategy reduces turning time and freezing of gait during turning, probably by lowering step time variability and asymmetry. Dual task compromises the effects of the clock-turn strategy, suggesting a competition for attentional resources.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, http://links.lww.com/JNPT/A141).

Age-Related Differences in Listening Effort During Degraded Speech Recognition.

PubMed

Ward, Kristina M; Shen, Jing; Souza, Pamela E; Grieco-Calub, Tina M

The purpose of the present study was to quantify age-related differences in executive control as it relates to dual-task performance, which is thought to represent listening effort, during degraded speech recognition. Twenty-five younger adults (YA; 18-24 years) and 21 older adults (OA; 56-82 years) completed a dual-task paradigm that consisted of a primary speech recognition task and a secondary visual monitoring task. Sentence material in the primary task was either unprocessed or spectrally degraded into 8, 6, or 4 spectral channels using noise-band vocoding. Performance on the visual monitoring task was assessed by the accuracy and reaction time of participants' responses. Performance on the primary and secondary task was quantified in isolation (i.e., single task) and during the dual-task paradigm. Participants also completed a standardized psychometric measure of executive control, including attention and inhibition. Statistical analyses were implemented to evaluate changes in listeners' performance on the primary and secondary tasks (1) per condition (unprocessed vs. vocoded conditions); (2) per task (single task vs. dual task); and (3) per group (YA vs. OA). Speech recognition declined with increasing spectral degradation for both YA and OA when they performed the task in isolation or concurrently with the visual monitoring task. OA were slower and less accurate than YA on the visual monitoring task when performed in isolation, which paralleled age-related differences in standardized scores of executive control. When compared with single-task performance, OA experienced greater declines in secondary-task accuracy, but not reaction time, than YA. Furthermore, results revealed that age-related differences in executive control significantly contributed to age-related differences on the visual monitoring task during the dual-task paradigm. OA experienced significantly greater declines in secondary-task accuracy during degraded speech recognition than YA. These findings are interpreted as suggesting that OA expended greater listening effort than YA, which may be partially attributed to age-related differences in executive control.

Skylab task and work performance /Experiment M-151 - Time and motion study/

NASA Technical Reports Server (NTRS)

Kubis, J. F.; Mclaughlin, E. J.

1975-01-01

The primary objective of Experiment M151 was to study the inflight adaptation of Skylab crewmen to a variety of task situations involving different types of activity. A parallel objective was to examine astronaut inflight performance for any behavioral stress effects associated with the working and living conditions of the Skylab environment. Training data provided the basis for comparison of preflight and inflight performance. Efficiency was evaluated through the adaptation function, namely, the relation of performance time over task trials. The results indicate that the initial changeover from preflight to inflight was accompanied by a substantial increase in performance time for most work and task activities. Equally important was the finding that crewmen adjusted rapidly to the weightless environment and became proficient in developing techniques with which to optimize task performance. By the end of the second inflight trial, most of the activities were performed almost as efficiently as on the last preflight trial. The analysis demonstrated the sensitivity of the adaptation function to differences in task and hardware configurations. The function was found to be more regular and less variable inflight than preflight. Translation and control of masses were accomplished easily and efficiently through the rapid development of the arms and legs as subtle guidance and restraint systems.

Activities of daily living measured by the Harvard Automated Phone Task track with cognitive decline over time in non-demented elderly.

PubMed

Marshall, Gad A; Aghjayan, Sarah L; Dekhtyar, Maria; Locascio, Joseph J; Jethwani, Kamal; Amariglio, Rebecca E; Johnson, Keith A; Sperling, Reisa A; Rentz, Dorene M

2017-01-01

Impairment in activities of daily living is a major burden to both patients and caregivers. Mild impairment in instrumental activities of daily living is often seen at the stage of mild cognitive impairment. The field of Alzheimer's disease is moving toward earlier diagnosis and intervention and more sensitive and ecologically valid assessments of instrumental or complex activities of daily living are needed. The Harvard Automated Phone Task, a novel performance-based activities of daily living instrument, has the potential to fill this gap. To further validate the Harvard Automated Phone Task by assessing its longitudinal relationship to global cognition and specific cognitive domains in clinically normal elderly and individuals with mild cognitive impairment. In a longitudinal study, the Harvard Automated Phone Task was associated with cognitive measures using mixed effects models. The Harvard Automated Phone Task's ability to discriminate across diagnostic groups at baseline was also assessed. Academic clinical research center. Two hundred and seven participants (45 young normal, 141 clinically normal elderly, and 21 mild cognitive impairment) were recruited from the community and the memory disorders clinics at Brigham and Women's Hospital and Massachusetts General Hospital. Participants performed the three tasks of the Harvard Automated Phone Task, which consist of navigating an interactive voice response system to refill a prescription (APT-Script), select a new primary care physician (APT-PCP), and make a bank account transfer and payment (APT-Bank). The 3 tasks were scored based on time, errors, repetitions, and correct completion of the task. The primary outcome measure used for each of the tasks was total time adjusted for correct completion. The Harvard Automated Phone Task discriminated well between young normal, clinically normal elderly, and mild cognitive impairment participants (APT-Script: p<0.001; APT-PCP: p<0.001; APT-Bank: p=0.04). Worse baseline Harvard Automated Phone Task performance or worsening Harvard Automated Phone Task performance over time tracked with overall worse performance or worsening performance over time in global cognition, processing speed, executive function, and episodic memory. Prior cross-sectional and current longitudinal analyses have demonstrated the utility of the Harvard Automated Phone Task, a new performance-based activities of daily living instrument, in the assessment of early changes in complex activities of daily living in non-demented elderly at risk for Alzheimer's disease. Future studies will focus on cross-validation with other sensitive activities of daily living tests and Alzheimer's disease biomarkers.

To speak or not to speak - A multiple resource perspective

NASA Technical Reports Server (NTRS)

Tsang, P. S.; Hartzell, E. J.; Rothschild, R. A.

1985-01-01

The desirability of employing speech response in a dynamic dual task situation was discussed from a multiple resource perspective. A secondary task technique was employed to examine the time-sharing performance of five dual tasks with various degrees of resource overlap according to the structure-specific resource model of Wickens (1980). The primary task was a visual/manual tracking task which required spatial processing. The secondary task was either another tracking task or a spatial transformation task with one of four input (visual or auditory) and output (manual or speech) configurations. The results show that the dual task performance was best when the primary tracking task was paired with the visual/speech transformation task. This finding was explained by an interaction of the stimulus-central processing-response compatibility of the transformation task and the degree of resource competition between the time-shared tasks. Implications on the utility of speech response were discussed.

Early Life Manipulations Alter Learning and Memory in Rats

PubMed Central

Kosten, Therese A; Kim, Jeansok J; Lee, Hongjoo J.

2012-01-01

Much research shows early life manipulations have enduring behavioral, neural, and hormonal effects. However, findings of learning and memory performance vary widely across studies. We reviewed studies in which pre-weaning rat pups were exposed to stressors and tested on learning and memory tasks in adulthood. Tasks were classified as aversive conditioning, inhibitory learning, or spatial/relational memory. Variables of duration, type, and timing of neonatal manipulation and sex and strain of animals were examined to determine if any predict enhanced or impaired performance. Brief separations enhanced and prolonged separations impaired performance on spatial/relational tasks. Performance was impaired in aversive conditioning and enhanced in inhibitory learning tasks regardless of manipulation duration. Opposing effects on performance for spatial/relational memory also depended upon timing of manipulation. Enhanced performance was likely if the manipulation occurred during postnatal week 3 but performance was impaired if it was confined to the first two postnatal weeks. Thus, the relationship between early life experiences and adulthood learning and memory performance is multifaceted and decidedly task-dependent. PMID:22819985

Performance Enhancements Under Dual-task Conditions

NASA Technical Reports Server (NTRS)

Kramer, A. F.; Wickens, C. D.; Donchin, E.

1984-01-01

Research on dual-task performance has been concerned with delineating the antecedent conditions which lead to dual-task decrements. Capacity models of attention, which propose that a hypothetical resource structure underlies performance, have been employed as predictive devices. These models predict that tasks which require different processing resources can be more successfully time shared than tasks which require common resources. The conditions under which such dual-task integrality can be fostered were assessed in a study in which three factors likely to influence the integrality between tasks were manipulated: inter-task redundancy, the physical proximity of tasks and the task relevant objects. Twelve subjects participated in three experimental sessions in which they performed both single and dual-tasks. The primary task was a pursuit step tracking task. The secondary tasks required the discrimination between different intensities or different spatial positions of a stimulus. The results are discussed in terms of a model of dual-task integrality.

Time for actions in lucid dreams: effects of task modality, length, and complexity

PubMed Central

Erlacher, Daniel; Schädlich, Melanie; Stumbrys, Tadas; Schredl, Michael

2014-01-01

The relationship between time in dreams and real time has intrigued scientists for centuries. The question if actions in dreams take the same time as in wakefulness can be tested by using lucid dreams where the dreamer is able to mark time intervals with prearranged eye movements that can be objectively identified in EOG recordings. Previous research showed an equivalence of time for counting in lucid dreams and in wakefulness (LaBerge, 1985; Erlacher and Schredl, 2004), but Erlacher and Schredl (2004) found that performing squats required about 40% more time in lucid dreams than in the waking state. To find out if the task modality, the task length, or the task complexity results in prolonged times in lucid dreams, an experiment with three different conditions was conducted. In the first condition, five proficient lucid dreamers spent one to three non-consecutive nights in the sleep laboratory. Participants counted to 10, 20, and 30 in wakefulness and in their lucid dreams. Lucidity and task intervals were time stamped with left-right-left-right eye movements. The same procedure was used for the second condition where eight lucid dreamers had to walk 10, 20, or 30 steps. In the third condition, eight lucid dreamers performed a gymnastics routine, which in the waking state lasted the same time as walking 10 steps. Again, we found that performing a motor task in a lucid dream requires more time than in wakefulness. Longer durations in the dream state were present for all three tasks, but significant differences were found only for the tasks with motor activity (walking and gymnastics). However, no difference was found for relative times (no disproportional time effects) and a more complex motor task did not result in more prolonged times. Longer durations in lucid dreams might be related to the lack of muscular feedback or slower neural processing during REM sleep. Future studies should explore factors that might be associated with prolonged durations. PMID:24474942

Time for actions in lucid dreams: effects of task modality, length, and complexity.

PubMed

Erlacher, Daniel; Schädlich, Melanie; Stumbrys, Tadas; Schredl, Michael

2013-01-01

The relationship between time in dreams and real time has intrigued scientists for centuries. The question if actions in dreams take the same time as in wakefulness can be tested by using lucid dreams where the dreamer is able to mark time intervals with prearranged eye movements that can be objectively identified in EOG recordings. Previous research showed an equivalence of time for counting in lucid dreams and in wakefulness (LaBerge, 1985; Erlacher and Schredl, 2004), but Erlacher and Schredl (2004) found that performing squats required about 40% more time in lucid dreams than in the waking state. To find out if the task modality, the task length, or the task complexity results in prolonged times in lucid dreams, an experiment with three different conditions was conducted. In the first condition, five proficient lucid dreamers spent one to three non-consecutive nights in the sleep laboratory. Participants counted to 10, 20, and 30 in wakefulness and in their lucid dreams. Lucidity and task intervals were time stamped with left-right-left-right eye movements. The same procedure was used for the second condition where eight lucid dreamers had to walk 10, 20, or 30 steps. In the third condition, eight lucid dreamers performed a gymnastics routine, which in the waking state lasted the same time as walking 10 steps. Again, we found that performing a motor task in a lucid dream requires more time than in wakefulness. Longer durations in the dream state were present for all three tasks, but significant differences were found only for the tasks with motor activity (walking and gymnastics). However, no difference was found for relative times (no disproportional time effects) and a more complex motor task did not result in more prolonged times. Longer durations in lucid dreams might be related to the lack of muscular feedback or slower neural processing during REM sleep. Future studies should explore factors that might be associated with prolonged durations.

The effects of stimulus modality and task integrality: Predicting dual-task performance and workload from single-task levels

NASA Technical Reports Server (NTRS)

Hart, S. G.; Shively, R. J.; Vidulich, M. A.; Miller, R. C.

1986-01-01

The influence of stimulus modality and task difficulty on workload and performance was investigated. The goal was to quantify the cost (in terms of response time and experienced workload) incurred when essentially serial task components shared common elements (e.g., the response to one initiated the other) which could be accomplished in parallel. The experimental tasks were based on the Fittsberg paradigm; the solution to a SternBERG-type memory task determines which of two identical FITTS targets are acquired. Previous research suggested that such functionally integrated dual tasks are performed with substantially less workload and faster response times than would be predicted by suming single-task components when both are presented in the same stimulus modality (visual). The physical integration of task elements was varied (although their functional relationship remained the same) to determine whether dual-task facilitation would persist if task components were presented in different sensory modalities. Again, it was found that the cost of performing the two-stage task was considerably less than the sum of component single-task levels when both were presented visually. Less facilitation was found when task elements were presented in different sensory modalities. These results suggest the importance of distinguishing between concurrent tasks that complete for limited resources from those that beneficially share common resources when selecting the stimulus modalities for information displays.

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.

The effect on surgical skills of expert surgeons using 3D/HD and 2D/4K resolution monitors in laparoscopic phantom tasks.

PubMed

Harada, Hitoshi; Kanaji, Shingo; Hasegawa, Hiroshi; Yamamoto, Masashi; Matsuda, Yoshiko; Yamashita, Kimihiro; Matsuda, Takeru; Oshikiri, Taro; Sumi, Yasuo; Nakamura, Tetsu; Suzuki, Satoshi; Kakeji, Yoshihiro

2018-03-30

Recently, several new imaging technologies, such as three-dimensional (3D)/high-definition (HD) stereovision and high-resolution two-dimensional (2D)/4K monitors, have been introduced in laparoscopic surgery. However, it is still unclear whether these technologies actually improve surgical performance. Participants were 11 expert laparoscopic surgeons. We designed three laparoscopic suturing tasks (task 1: simple suturing, task 2: knotting thread in a small box, and task 3: suturing in a narrow space) in training boxes. Performances were recorded by an optical position tracker. All participants first performed each task five times consecutively using a conventional 2D/HD monitor. Then they were randomly divided into two groups: six participants performed the tasks using 3D/HD before using 2D/4K; the other five participants performed the tasks using a 2D/4K monitor before the 3D/HD monitor. After the trials, we evaluated the performance scores (operative time, path length of forceps, and technical errors) and compared performance scores across all monitors. Surgical performances of participants were ranked in decreasing order: 3D/HD, 2D/4K, and 2D/HD using the total scores for each task. In task 1 (simple suturing), some surgical performances using 3D/HD were significantly better than those using 2D/4K (P = 0.017, P = 0.033, P = 0.492 for operative time, path length, and technical errors, respectively). On the other hand, with operation in narrow spaces such as in tasks 2 and 3, performances using 2D/4K were not inferior to 3D/HD performances. The high-resolution images from the 2D/4K monitor may enhance depth perception in narrow spaces and may complement stereoscopic vision almost as well as using 3D/HD. Compared to a 2D/HD monitor, a 3D/HD monitor improved the laparoscopic surgical technique of expert surgeons more than a 2D/4K monitor. However, the advantage of 2D/4K high-resolution images may be comparable to a 3D/HD monitor especially in narrow spaces.

Designing a fuzzy scheduler for hard real-time systems

NASA Technical Reports Server (NTRS)

Yen, John; Lee, Jonathan; Pfluger, Nathan; Natarajan, Swami

1992-01-01

In hard real-time systems, tasks have to be performed not only correctly, but also in a timely fashion. If timing constraints are not met, there might be severe consequences. Task scheduling is the most important problem in designing a hard real-time system, because the scheduling algorithm ensures that tasks meet their deadlines. However, the inherent nature of uncertainty in dynamic hard real-time systems increases the problems inherent in scheduling. In an effort to alleviate these problems, we have developed a fuzzy scheduler to facilitate searching for a feasible schedule. A set of fuzzy rules are proposed to guide the search. The situation we are trying to address is the performance of the system when no feasible solution can be found, and therefore, certain tasks will not be executed. We wish to limit the number of important tasks that are not scheduled.

Factors Contributing to Single- and Dual-Task Timed "Up & Go" Test Performance in Middle-Aged and Older Adults Who Are Active and Dwell in the Community.

PubMed

Chen, Hui-Ya; Tang, Pei-Fang

2016-03-01

Dual-task Timed "Up & Go" (TUG) tests are likely to have applications different from those of a single-task TUG test and may have different contributing factors. The purpose of this study was to compare factors contributing to performance on single- and dual-task TUG tests. This investigation was a cross-sectional study. Sixty-four adults who were more than 50 years of age and dwelled in the community were recruited. Interviews and physical examinations were performed to identify potential contributors to TUG test performance. The time to complete the single-task TUG test (TUGsingle) or the dual-task TUG test, which consisted of completing the TUG test while performing a serial subtraction task (TUGcognitive) or while carrying water (TUGmanual), was measured. Age, hip extensor strength, walking speed, general mental function, and Stroop scores for word and color were significantly associated with performance on all TUG tests. Hierarchical multiple regression models, without the input of walking speed, revealed different independent factors contributing to TUGsingle performance (Mini-Mental Status Examination score, β=-0.32), TUGmanual performance (age, β=0.35), and TUGcognitive performance (Stroop word score, β=-0.40; Mini-Mental Status Examination score, β=-0.31). At least 40% of the variance in the performance on the 3 TUG tests was not explained by common clinical measures, even when the factor of walking speed was considered. However, this study successfully identified some important factors contributing to performance on different TUG tests, and other studies have reported similar findings for single-task TUG test and dual-task gait performance. Although the TUGsingle and the TUGcognitive shared general mental function as a common factor, the TUGmanual was uniquely influenced by age and the TUGcognitive was uniquely influenced by focused attention. These results suggest that both common and unique factors contribute to performance on single- and dual-task TUG tests and suggest important applications of the combined use of the 3 TUG tests. © 2016 American Physical Therapy Association.

The phantom robot - Predictive displays for teleoperation with time delay

NASA Technical Reports Server (NTRS)

Bejczy, Antal K.; Kim, Won S.; Venema, Steven C.

1990-01-01

An enhanced teleoperation technique for time-delayed bilateral teleoperator control is discussed. The control technique selected for time delay is based on the use of a high-fidelity graphics phantom robot that is being controlled in real time (without time delay) against the static task image. Thus, the motion of the phantom robot image on the monitor predicts the motion of the real robot. The real robot's motion will follow the phantom robot's motion on the monitor with the communication time delay implied in the task. Real-time high-fidelity graphics simulation of a PUMA arm is generated and overlaid on the actual camera view of the arm. A simple camera calibration technique is used for calibrated graphics overlay. A preliminary experiment is performed with the predictive display by using a very simple tapping task. The results with this simple task indicate that predictive display enhances the human operator's telemanipulation task performance significantly during free motion when there is a long time delay. It appears, however, that either two-view or stereoscopic predictive displays are necessary for general three-dimensional tasks.

Design and implementation of laser target simulator in hardware-in-the-loop simulation system based on LabWindows/CVI and RTX

NASA Astrophysics Data System (ADS)

Tong, Qiujie; Wang, Qianqian; Li, Xiaoyang; Shan, Bin; Cui, Xuntai; Li, Chenyu; Peng, Zhong

2016-11-01

In order to satisfy the requirements of the real-time and generality, a laser target simulator in semi-physical simulation system based on RTX+LabWindows/CVI platform is proposed in this paper. Compared with the upper-lower computers simulation platform architecture used in the most of the real-time system now, this system has better maintainability and portability. This system runs on the Windows platform, using Windows RTX real-time extension subsystem to ensure the real-time performance of the system combining with the reflective memory network to complete some real-time tasks such as calculating the simulation model, transmitting the simulation data, and keeping real-time communication. The real-time tasks of simulation system run under the RTSS process. At the same time, we use the LabWindows/CVI to compile a graphical interface, and complete some non-real-time tasks in the process of simulation such as man-machine interaction, display and storage of the simulation data, which run under the Win32 process. Through the design of RTX shared memory and task scheduling algorithm, the data interaction between the real-time tasks process of RTSS and non-real-time tasks process of Win32 is completed. The experimental results show that this system has the strongly real-time performance, highly stability, and highly simulation accuracy. At the same time, it also has the good performance of human-computer interaction.

A Role for Memory in Prospective Timing informs Timing in Prospective Memory

PubMed Central

Waldum, Emily R; Sahakyan, Lili

2014-01-01

Time-based prospective memory (TBPM) tasks require the estimation of time in passing – known as prospective timing. Prospective timing is said to depend on an attentionally-driven internal clock mechanism, and is thought to be unaffected by memory for interval information (for reviews see, Block, Hancock, & Zakay, 2010; Block & Zakay, 1997). A prospective timing task that required a verbal estimate following the entire interval (Experiment 1) and a TBPM task that required production of a target response during the interval (Experiment 2) were used to test an alternative view that episodic memory does influence prospective timing. In both experiments, participants performed an ongoing lexical decision task of fixed duration while a varying number of songs were played in the background. Experiment 1 results revealed that verbal time estimates became longer the more songs participants remembered from the interval, suggesting that memory for interval information influences prospective time estimates. In Experiment 2, participants who were asked to perform the TBPM task without the aid of an external clock made their target responses earlier as the number of songs increased, indicating that prospective estimates of elapsed time increased as more songs were experienced. For participants who had access to a clock, changes in clock-checking coincided with the occurrence of song boundaries, indicating that participants used both song information and clock information to estimate time. Finally, ongoing task performance and verbal reports in both experiments further substantiate a role for episodic memory in prospective timing. PMID:22984950

The Effect of Task Repetition on Fluency and Accuracy of EFL Saudi Female Learners' Oral Performance

ERIC Educational Resources Information Center

Gashan, Amani K.; Almohaisen, Fahad M.

2014-01-01

This study aimed to examine the effect of task repetition on foreign language output. Twenty eight Saudi female students in the Preparatory Year (PY) at King Saud university, were randomly selected to conduct an oral information-gap task. The participants were asked to perform the task two times with two-week interval between the two performances.…

Cognitive demand of human sensorimotor performance during an extended space mission: a dual-task study.

PubMed

Bock, Otmar; Weigelt, Cornelia; Bloomberg, Jacob J

2010-09-01

Two previous single-case studies found that the dual-task costs of manual tracking plus memory search increased during a space mission, and concluded that sensorimotor deficits during spaceflight may be related to cognitive overload. Since dual-task costs were insensitive to the difficulty of memory search, the authors argued that the overload may reflect stress-related problems of multitasking, rather than a scarcity of specific cognitive resources. Here we expand the available database and compare different types of concurrent task. Three subjects were repeatedly tested before, during, and after an extended mission on the International Space Station (ISS). They performed an unstable tracking task and four reaction-time tasks, both separately and concurrently. Inflight data could only be obtained during later parts of the mission. The tracking error increased from pre- to in flight by a factor of about 2, both under single- and dual-task conditions. The dual-task costs with a reaction-time task requiring rhythm production was 2.4 times higher than with a reaction-time task requiring visuo-spatial transformations, and 8 times higher than with a regular choice reaction-time task. Long-term sensorimotor deficits during spaceflight may reflect not only stress, but also a scarcity of resources related to complex motor programming; possibly those resources are tied up by sensorimotor adaptation to the space environment.

Dynamic Resource Management for Parallel Tasks in an Oversubscribed Energy-Constrained Heterogeneous Environment

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

Imam, Neena; Koenig, Gregory A; Machovec, Dylan

2016-01-01

Abstract: The worth of completing parallel tasks is modeled using utility functions, which monotonically-decrease with time and represent the importance and urgency of a task. These functions define the utility earned by a task at the time of its completion. The performance of such a system is measured as the total utility earned by all completed tasks over some interval of time (e.g., 24 hours). To maximize system performance when scheduling dynamically arriving parallel tasks onto a high performance computing (HPC) system that is oversubscribed and energy-constrained, we have designed, analyzed, and compared different heuristic techniques. Four utility-aware heuristics (i.e.,more » Max Utility, Max Utility-per-Time, Max Utility-per-Resource, and Max Utility-per-Energy), three FCFS-based heuristics (Conservative Backfilling, EASY Backfilling, and FCFS with Multiple Queues), and a Random heuristic were examined in this study. A technique that is often used with the FCFS-based heuristics is the concept of a permanent reservation. We compare the performance of permanent reservations with temporary place-holders to demonstrate the advantages that place-holders can provide. We also present a novel energy filtering technique that constrains the maximum energy-per-resource used by each task. We conducted a simulation study to evaluate the performance of these heuristics and techniques in an energy-constrained oversubscribed HPC environment. With place-holders, energy filtering, and dropping tasks with low potential utility, our utility-aware heuristics are able to significantly outperform the existing FCFS-based techniques.« less

Incorrect predictions reduce switch costs.

PubMed

Kleinsorge, Thomas; Scheil, Juliane

2015-07-01

In three experiments, we combined two sources of conflict within a modified task-switching procedure. The first source of conflict was the one inherent in any task switching situation, namely the conflict between a task set activated by the recent performance of another task and the task set needed to perform the actually relevant task. The second source of conflict was induced by requiring participants to guess aspects of the upcoming task (Exps. 1 & 2: task identity; Exp. 3: position of task precue). In case of an incorrect guess, a conflict accrues between the representation of the guessed task and the actually relevant task. In Experiments 1 and 2, incorrect guesses led to an overall increase of reaction times and error rates, but they reduced task switch costs compared to conditions in which participants predicted the correct task. In Experiment 3, incorrect guesses resulted in faster performance overall and to a selective decrease of reaction times in task switch trials when the cue-target interval was long. We interpret these findings in terms of an enhanced level of controlled processing induced by a combination of two sources of conflict converging upon the same target of cognitive control. Copyright © 2015 Elsevier B.V. All rights reserved.

Nominal and functional task difficulty in skill acquisition: Effects on performance in two tests of transfer.

PubMed

Sanli, Elizabeth A; Lee, Timothy D

2015-06-01

The influence of nominal and functional task difficulty during the acquisition of a motor skill was examined in two tests of transfer of learning. The task involved a ballistic, target-directed, finger action. Nominal task difficulty was defined as the distance of the target from the home position. Functional task difficulty was created by manipulating the progression of target distances during practice. Based on the challenge point framework (Guadagnoli & Lee, 2004), we predicted that practice with a set of targets farther away from the performer would benefit from less functional task difficulty, while practice with a closer set of targets would benefit from more functional task difficulty. In single-task transfer tests, learners who practiced using the high nominal task difficulty targets benefitted in terms of persistence of performance over time. In dual-task transfer tests, groups with an intermediate combined (nominal and functional) task difficulty performed with greater persistence over time on tests of transfer than those who practiced with the highest or lowest combined difficulty. Together these findings suggest that the influences of nominal and functional task difficulty during acquisition are weighted differentially depending upon the transfer test context. The challenge point framework does not accurately capture this complex relationship in its current form. Copyright © 2015 Elsevier B.V. All rights reserved.

Activities of daily living measured by the Harvard Automated Phone Task track with cognitive decline over time in non-demented elderly

PubMed Central

Marshall, Gad A.; Aghjayan, Sarah L.; Dekhtyar, Maria; Locascio, Joseph J.; Jethwani, Kamal; Amariglio, Rebecca E.; Johnson, Keith A.; Sperling, Reisa A.; Rentz, Dorene M.

2017-01-01

Background Impairment in activities of daily living is a major burden to both patients and caregivers. Mild impairment in instrumental activities of daily living is often seen at the stage of mild cognitive impairment. The field of Alzheimer’s disease is moving toward earlier diagnosis and intervention and more sensitive and ecologically valid assessments of instrumental or complex activities of daily living are needed. The Harvard Automated Phone Task, a novel performance-based activities of daily living instrument, has the potential to fill this gap. Objective To further validate the Harvard Automated Phone Task by assessing its longitudinal relationship to global cognition and specific cognitive domains in clinically normal elderly and individuals with mild cognitive impairment. Design In a longitudinal study, the Harvard Automated Phone Task was associated with cognitive measures using mixed effects models. The Harvard Automated Phone Task’s ability to discriminate across diagnostic groups at baseline was also assessed. Setting Academic clinical research center. Participants Two hundred and seven participants (45 young normal, 141 clinically normal elderly, and 21 mild cognitive impairment) were recruited from the community and the memory disorders clinics at Brigham and Women’s Hospital and Massachusetts General Hospital. Measurements Participants performed the three tasks of the Harvard Automated Phone Task, which consist of navigating an interactive voice response system to refill a prescription (APT-Script), select a new primary care physician (APT-PCP), and make a bank account transfer and payment (APT-Bank). The 3 tasks were scored based on time, errors, repetitions, and correct completion of the task. The primary outcome measure used for each of the tasks was total time adjusted for correct completion. Results The Harvard Automated Phone Task discriminated well between young normal, clinically normal elderly, and mild cognitive impairment participants (APT-Script: p<0.001; APT-PCP: p<0.001; APT-Bank: p=0.04). Worse baseline Harvard Automated Phone Task performance or worsening Harvard Automated Phone Task performance over time tracked with overall worse performance or worsening performance over time in global cognition, processing speed, executive function, and episodic memory. Conclusions Prior cross-sectional and current longitudinal analyses have demonstrated the utility of the Harvard Automated Phone Task, a new performance-based activities of daily living instrument, in the assessment of early changes in complex activities of daily living in non-demented elderly at risk for Alzheimer’s disease. Future studies will focus on cross-validation with other sensitive activities of daily living tests and Alzheimer’s disease biomarkers. PMID:29124043

Is Single-Port Laparoscopy More Precise and Faster with the Robot?

PubMed

Fransen, Sofie A F; van den Bos, Jacqueline; Stassen, Laurents P S; Bouvy, Nicole D

2016-11-01

Single-port laparoscopy is a step forward toward nearly scar less surgery. Concern has been raised that single-incision laparoscopic surgery (SILS) is technically more challenging because of the lack of triangulation and the clashing of instruments. Robotic single-incision laparoscopic surgery (RSILS) in chopstick setting might overcome these problems. This study evaluated the outcome in time and errors of two tasks of the Fundamentals of Laparoscopic Surgery on a dry platform, in two settings: SILS versus RSILS. Nine experienced laparoscopic surgeons performed two tasks: peg transfer and a suturing task, on a standard box trainer. All participants practiced each task three times in both settings: SILS and a RSILS setting. The assessment scores (time and errors) were recorded. For the first task of peg transfer, RSILS was significantly better in time (124 versus 230 seconds, P = .0004) and errors (0.80 errors versus 2.60 errors, P = .024) at the first run, compared to the SILS setting. At the third and final run, RSILS still proved to be significantly better in errors (0.10 errors versus 0.80 errors, P = .025) compared to the SILS group. RSILS was faster in the third run, but not significant (116 versus 157 seconds, P = .08). For the second task, a suturing task, only 3 participants of the SILS group were able to perform this task within the set time frame of 600 seconds. There was no significant difference in time in the three runs between SILS and RSILS for the 3 participants that fulfilled both tasks within the 600 seconds. This study shows that robotic single-port surgery seems easier, faster, and more precise to perform basis tasks of the Fundamentals of laparoscopic surgery. For the more complex task of suturing, only the single-port robotic setting enabled all participants to fulfill this task, within the set time frame.

Music and Sound in Time Processing of Children with ADHD

PubMed Central

Carrer, Luiz Rogério Jorgensen

2015-01-01

ADHD involves cognitive and behavioral aspects with impairments in many environments of children and their families’ lives. Music, with its playful, spontaneous, affective, motivational, temporal, and rhythmic dimensions can be of great help for studying the aspects of time processing in ADHD. In this article, we studied time processing with simple sounds and music in children with ADHD with the hypothesis that children with ADHD have a different performance when compared with children with normal development in tasks of time estimation and production. The main objective was to develop sound and musical tasks to evaluate and correlate the performance of children with ADHD, with and without methylphenidate, compared to a control group with typical development. The study involved 36 participants of age 6–14 years, recruited at NANI-UNIFESP/SP, subdivided into three groups with 12 children in each. Data was collected through a musical keyboard using Logic Audio Software 9.0 on the computer that recorded the participant’s performance in the tasks. Tasks were divided into sections: spontaneous time production, time estimation with simple sounds, and time estimation with music. Results: (1) performance of ADHD groups in temporal estimation of simple sounds in short time intervals (30 ms) were statistically lower than that of control group (p < 0.05); (2) in the task comparing musical excerpts of the same duration (7 s), ADHD groups considered the tracks longer when the musical notes had longer durations, while in the control group, the duration was related to the density of musical notes in the track. The positive average performance observed in the three groups in most tasks perhaps indicates the possibility that music can, in some way, positively modulate the symptoms of inattention in ADHD. PMID:26441688

Music and Sound in Time Processing of Children with ADHD.

PubMed

Carrer, Luiz Rogério Jorgensen

2015-01-01

ADHD involves cognitive and behavioral aspects with impairments in many environments of children and their families' lives. Music, with its playful, spontaneous, affective, motivational, temporal, and rhythmic dimensions can be of great help for studying the aspects of time processing in ADHD. In this article, we studied time processing with simple sounds and music in children with ADHD with the hypothesis that children with ADHD have a different performance when compared with children with normal development in tasks of time estimation and production. The main objective was to develop sound and musical tasks to evaluate and correlate the performance of children with ADHD, with and without methylphenidate, compared to a control group with typical development. The study involved 36 participants of age 6-14 years, recruited at NANI-UNIFESP/SP, subdivided into three groups with 12 children in each. Data was collected through a musical keyboard using Logic Audio Software 9.0 on the computer that recorded the participant's performance in the tasks. Tasks were divided into sections: spontaneous time production, time estimation with simple sounds, and time estimation with music. (1) performance of ADHD groups in temporal estimation of simple sounds in short time intervals (30 ms) were statistically lower than that of control group (p < 0.05); (2) in the task comparing musical excerpts of the same duration (7 s), ADHD groups considered the tracks longer when the musical notes had longer durations, while in the control group, the duration was related to the density of musical notes in the track. The positive average performance observed in the three groups in most tasks perhaps indicates the possibility that music can, in some way, positively modulate the symptoms of inattention in ADHD.

The Crosstalk Hypothesis: Why Language Interferes with Driving

ERIC Educational Resources Information Center

Bergen, Benjamin; Medeiros-Ward, Nathan; Wheeler, Kathryn; Drews, Frank; Strayer, David

2013-01-01

Performing two cognitive tasks at the same time can degrade performance for either domain-general reasons (e.g., both tasks require attention) or domain-specific reasons (e.g., both tasks require visual working memory). We tested predictions of these two accounts of interference on the task of driving while using language, a naturally occurring…

A Novel Connectionist Network for Solving Long Time-Lag Prediction Tasks

NASA Astrophysics Data System (ADS)

Johnson, Keith; MacNish, Cara

Traditional Recurrent Neural Networks (RNNs) perform poorly on learning tasks involving long time-lag dependencies. More recent approaches such as LSTM and its variants significantly improve on RNNs ability to learn this type of problem. We present an alternative approach to encoding temporal dependencies that associates temporal features with nodes rather than state values, where the nodes explicitly encode dependencies over variable time delays. We show promising results comparing the network's performance to LSTM variants on an extended Reber grammar task.

Individual differences in implicit motor learning: task specificity in sensorimotor adaptation and sequence learning.

PubMed

Stark-Inbar, Alit; Raza, Meher; Taylor, Jordan A; Ivry, Richard B

2017-01-01

In standard taxonomies, motor skills are typically treated as representative of implicit or procedural memory. We examined two emblematic tasks of implicit motor learning, sensorimotor adaptation and sequence learning, asking whether individual differences in learning are correlated between these tasks, as well as how individual differences within each task are related to different performance variables. As a prerequisite, it was essential to establish the reliability of learning measures for each task. Participants were tested twice on a visuomotor adaptation task and on a sequence learning task, either the serial reaction time task or the alternating reaction time task. Learning was evident in all tasks at the group level and reliable at the individual level in visuomotor adaptation and the alternating reaction time task but not in the serial reaction time task. Performance variability was predictive of learning in both domains, yet the relationship was in the opposite direction for adaptation and sequence learning. For the former, faster learning was associated with lower variability, consistent with models of sensorimotor adaptation in which learning rates are sensitive to noise. For the latter, greater learning was associated with higher variability and slower reaction times, factors that may facilitate the spread of activation required to form predictive, sequential associations. Interestingly, learning measures of the different tasks were not correlated. Together, these results oppose a shared process for implicit learning in sensorimotor adaptation and sequence learning and provide insight into the factors that account for individual differences in learning within each task domain. We investigated individual differences in the ability to implicitly learn motor skills. As a prerequisite, we assessed whether individual differences were reliable across test sessions. We found that two commonly used tasks of implicit learning, visuomotor adaptation and the alternating serial reaction time task, exhibited good test-retest reliability in measures of learning and performance. However, the learning measures did not correlate between the two tasks, arguing against a shared process for implicit motor learning. Copyright © 2017 the American Physiological Society.

SKread predicts handwriting performance in patients with low vision.

PubMed

Downes, Ken; Walker, Laura L; Fletcher, Donald C

2015-06-01

To assess whether performance on the Smith-Kettlewell Reading (SKread) test is a reliable predictor of handwriting performance in patients with low vision. Cross-sectional study. Sixty-six patients at their initial low-vision rehabilitation evaluation. The patients completed all components of a routine low-vision appointment including logMAR acuity, performed the SKread test, and performed a handwriting task. Patients were timed while performing each task and their accuracy was recorded. The handwriting task was performed by having patients write 5 5-letter words into sets of boxes where each letter is separated by a box. The boxes were 15 × 15 mm, and accuracy was scored with 50 points possible from 25 letters: 1 point for each letter within the confines of a box and 1 point if the letter was legible. Correlation analysis was then performed. Median age of participants was 84 (range 54-97) years. Fifty-seven patients (86%) had age-related macular degeneration or some other maculopathy, whereas 9 patients (14%) had visual impairment from media opacity or neurologic impairment. Median Early Treatment Diabetic Retinopathy Study acuity was 20/133 (range 20/22 to 20/1000), and median logMAR acuity was 0.82 (range 0.04-1.70). SKread errors per block correlated with logMAR acuity (r = 0.6), and SKread time per block correlated with logMAR acuity (r = 0.51). SKread errors per block correlated with handwriting task time/accuracy ratio (r = 0.61). SKread time per block correlated with handwriting task time/accuracy ratio (r = 0.7). LogMAR acuity score correlated with handwriting task time/accuracy ratio (r = 0.42). All p values were < 0.01. SKread scores predict handwriting performance in patients with low vision better than logMAR acuity. Copyright © 2015 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

Soft-light overhead illumination systems improve laparoscopic task performance.

PubMed

Takai, Akihiro; Takada, Yasutsugu; Motomura, Hideki; Teramukai, Satoshi

2014-02-01

The aim of this study was to evaluate the impact of attached shadow cues for laparoscopic task performance. We developed a soft-light overhead illumination system (SOIS) that produced attached shadows on objects. We compared results using the SOIS with those using a conventional illumination system with regard to laparoscopic experience and laparoscope-to-target distances (LTDs). Forty-two medical students and 23 surgeons participated in the study. A peg transfer task (LTD, 120 mm) for students and surgeons, and a suture removal task (LTD, 30 mm) for students were performed. Illumination systems were randomly assigned to each task. Endpoints were: total number of peg transfers; percentage of peg-dropping errors; and total execution time for suture removal. After the task, participants filled out a questionnaire on their preference for a particular illumination system. Total number of peg transfers was greater with the SOIS for both students and surgeons. Percentage of peg-dropping errors for surgeons was lower with the SOIS. Total execution time for suture removal was shorter with the SOIS. Forty-five participants (69% in total) evaluated the SOIS for easier task performance. The present results confirm that the SOIS improves laparoscopic task performance, regardless of previous laparoscopic experience or LTD.

Integrated Design of a Telerobotic Workstation

NASA Technical Reports Server (NTRS)

Rochlis, Jennifer L.; Clarke, John-Paul

2001-01-01

The experiments described in this paper are part of a larger joint MIT/NASA research effort that focuses on the development of a methodology for designing and evaluating integrated interfaces for highly dexterous and multi-functional telerobots. Specifically, a telerobotic workstation is being designed for an Extravehicular Activity (EVA) anthropomorphic space station telerobot. Previous researchers have designed telerobotic workstations based upon performance of discrete subsets of tasks (for example, peg-in-hole, tracking, etc.) without regard for transitions that operators go through between tasks performed sequentially in the context of larger integrated tasks. The exploratory research experiments presented here took an integrated approach and assessed how subjects operating a full-immersion telerobot perform during the transitions between sub-tasks of two common EVA tasks. Preliminary results show that up to 30% of total task time is spent gaining and maintaining Situation Awareness (SA) of their task space and environment during transitions. Although task performance improves over the two trial days, the percentage of time spent on SA remains the same. This method identifies areas where workstation displays and feedback mechanisms are most needed to increase operator performance and decrease operator workload - areas that previous research methods have not been able to address.

The role of mental rotation and memory scanning on the performance of laparoscopic skills: a study on the effect of camera rotational angle.

PubMed

Conrad, J; Shah, A H; Divino, C M; Schluender, S; Gurland, B; Shlasko, E; Szold, A

2006-03-01

The rotational angle of the laparoscopic image relative to the true horizon has an unknown influence on performance in laparoscopic procedures. This study evaluates the effect of increasing rotational angle on surgical performance. Surgical residents (group 1) (n = 6) and attending surgeons (group 2) (n = 4) were tested on two laparoscopic skills. The tasks consisted of passing a suture through an aperture, and laparoscopic knot tying. These tasks were assessed at 15 degrees intervals between 0 degrees and 90 degrees , on three consecutive repetitions. The participant's performance was evaluated based on the time required to complete the tasks and number of errors incurred. There was an increasing deterioration in suturing performance as the degree of image rotation was increased. Participants showed a statistically significant 20-120% progressive increase in time to completion of the tasks (p = 0.004), with error rates increasing from 10% to 30% (p = 0.04) as the angle increased from 0 degrees to 90 degrees. Knot-tying performance similarly showed a decrease in performance that was evident in the less experienced surgeons (p = 0.02) but with no obvious effect on the advanced laparoscopic surgeons. When evaluated independently and as a group, both novice and experienced laparoscopic surgeons showed significant prolongation to completion of suturing tasks with increased errors as the rotational angle increased. The knot-tying task shows that experienced surgeons may be able to overcome rotational effects to some extent. This is consistent with results from cognitive neuroscience research evaluating the processing of directional information in spatial motor tasks. It appears that these tasks utilize the time-consuming processes of mental rotation and memory scanning. Optimal performance during laparoscopic procedures requires that the rotation of the camera, and thus the image, be kept to a minimum to maintain a stable horizon. New technology that corrects the rotational angle may benefit the surgeon, decrease operating time, and help to prevent adverse outcomes.

Assessing performance of an Electronic Health Record (EHR) using Cognitive Task Analysis.

PubMed

Saitwal, Himali; Feng, Xuan; Walji, Muhammad; Patel, Vimla; Zhang, Jiajie

2010-07-01

Many Electronic Health Record (EHR) systems fail to provide user-friendly interfaces due to the lack of systematic consideration of human-centered computing issues. Such interfaces can be improved to provide easy to use, easy to learn, and error-resistant EHR systems to the users. To evaluate the usability of an EHR system and suggest areas of improvement in the user interface. The user interface of the AHLTA (Armed Forces Health Longitudinal Technology Application) was analyzed using the Cognitive Task Analysis (CTA) method called GOMS (Goals, Operators, Methods, and Selection rules) and an associated technique called KLM (Keystroke Level Model). The GOMS method was used to evaluate the AHLTA user interface by classifying each step of a given task into Mental (Internal) or Physical (External) operators. This analysis was performed by two analysts independently and the inter-rater reliability was computed to verify the reliability of the GOMS method. Further evaluation was performed using KLM to estimate the execution time required to perform the given task through application of its standard set of operators. The results are based on the analysis of 14 prototypical tasks performed by AHLTA users. The results show that on average a user needs to go through 106 steps to complete a task. To perform all 14 tasks, they would spend about 22 min (independent of system response time) for data entry, of which 11 min are spent on more effortful mental operators. The inter-rater reliability analysis performed for all 14 tasks was 0.8 (kappa), indicating good reliability of the method. This paper empirically reveals and identifies the following finding related to the performance of AHLTA: (1) large number of average total steps to complete common tasks, (2) high average execution time and (3) large percentage of mental operators. The user interface can be improved by reducing (a) the total number of steps and (b) the percentage of mental effort, required for the tasks. 2010 Elsevier Ireland Ltd. All rights reserved.

Consistent Performance Differences between Children and Adults Despite Manipulation of Cue-Target Variables

PubMed Central

Bauer, Jessie-Raye; Martinez, Joel E.; Roe, Mary Abbe; Church, Jessica A.

2017-01-01

Two behavioral experiments assessed the plasticity and short-term improvement of task switching in 215 children and adults. Specifically, we studied manipulations of cued attention to different features of a target stimulus as a way to assess the development of cognitive flexibility. Each experiment had multiple levels of difficulty via manipulation of number of cued features (2–4) and number of response options (2 or 4). Working memory demand was manipulated across the two experiments. Impact of memory demand and task level manipulations on task accuracy and response times were measured. There were three overall goals: First, these task manipulations (number of cued features, response choices, and working memory load) were tested to assess the stability of group differences in performance between children ages 6–16 years and adults 18–27 years, with the goal of reducing age group differences. Second, age-related transitions to adult-level performance were examined within subgroups of the child sample. Third, short-term improvement from the beginning to the end of the study session was measured to probe whether children can improve with task experience. Attempts to use task manipulations to reduce age differences in cued task switching performance were unsuccessful: children performed consistently worse and were more susceptible to task manipulations than adults. However, across both studies, adult-like performance was observed around mid-adolescence, by ages 13-16 years. Certain task manipulations, especially increasing number of response options when working memory demand was low, produced differences from adults even in the oldest children. Interestingly, there was similar performance improvement with practice for both child and adult groups. The higher memory demand version of the task (Experiment 2) prompted greater short-term improvement in accuracy and response times than the lower memory demand version (Experiment 1). These results reveal stable differences in cued switching performance over development, but also relative flexibility within a given individual over time. PMID:28824489

Does a 3D Image Improve Laparoscopic Motor Skills?

PubMed

Folaranmi, Semiu Eniola; Partridge, Roland W; Brennan, Paul M; Hennessey, Iain A M

2016-08-01

To quantitatively determine whether a three-dimensional (3D) image improves laparoscopic performance compared with a two-dimensional (2D) image. This is a prospective study with two groups of participants: novices (5) and experts (5). Individuals within each group undertook a validated laparoscopic task on a box simulator, alternating between 2D and a 3D laparoscopic image until they had repeated the task five times with each imaging modality. A dedicated motion capture camera was used to determine the time taken to complete the task (seconds) and instrument distance traveled (meters). Among the experts, the mean time taken to perform the task on the 3D image was significantly quicker than on the 2D image, 40.2 seconds versus 51.2 seconds, P < .0001. Among the novices, the mean task time again was significantly quicker on the 3D image, 56.4 seconds versus 82.7 seconds, P < .0001. There was no significant difference in the mean time it took a novice to perform the task using a 3D camera compared with an expert on a 2D camera, 56.4 seconds versus 51.3 seconds, P = .3341. The use of a 3D image confers a significant performance advantage over a 2D camera in quantitatively measured laparoscopic skills for both experts and novices. The use of a 3D image appears to improve a novice's performance to the extent that it is not statistically different from an expert using a 2D image.

Physiological, subjective, and performance correlates of reported boredom and monotony while performing a simulated radar control task.

DOT National Transportation Integrated Search

1975-01-01

Forty-five male subjects performed a simulated air traffic control radar task for 1 hour. Subjects were equally divided into three time-of-day groups and tested at 1000, 1300, and 1530. The subject's task was to respond as rapidly as possible to infr...

Valence and arousal of emotional stimuli impact cognitive-motor performance in an oddball task.

PubMed

Lu, Yingzhi; Jaquess, Kyle J; Hatfield, Bradley D; Zhou, Chenglin; Li, Hong

2017-04-01

It is widely recognized that emotions impact an individual's ability to perform in a given task. However, little is known about how emotion impacts the various aspects of cognitive -motor performance. We recorded event-related potentials (ERPs) and chronometric responses from twenty-six participants while they performed a cognitive-motor oddball task in regard to four categories of emotional stimuli (high-arousing positive-valence, low-arousing positive-valence, high-arousing negative-valence, and low-arousing negative-valence) as "deviant" stimuli. Six chronometric responses (reaction time, press time, return time, choice time, movement time, and total time) and three ERP components (P2, N2 and late positive potential) were measured. Results indicated that reaction time was significantly affected by the presentation of emotional stimuli. Also observed was a negative relationship between N2 amplitude and elements of performance featuring reaction time in the low-arousing positive-valence condition. This study provides further evidence that emotional stimuli influence cognitive-motor performance in a specific manner. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparative assessment of laparoscopic single-site surgery instruments to conventional laparoscopic in laboratory setting.

PubMed

Stolzenburg, Jens-Uwe; Kallidonis, Panagiotis; Oh, Min-A; Ghulam, Nabi; Do, Minh; Haefner, Tim; Dietel, Anja; Till, Holger; Sakellaropoulos, George; Liatsikos, Evangelos N

2010-02-01

Laparoendoscopic single-site surgery (LESS) represents the latest innovation in laparoscopic surgery. We compare in dry and animal laboratory the efficacy of recently introduced pre-bent instruments with conventional laparoscopic and flexible instruments in terms of time requirement, maneuverability, and ease of handling. Participants of varying laparoscopic experience were included in the study and divided in groups according to their experience. The participants performed predetermined tasks in dry laboratory using all sets of instruments. An experienced laparoscopic surgeon performed 24 nephrectomies in 12 pigs using all sets of instruments. Single port was used for all instrument sets except for the conventional instruments, which were inserted through three ports. The time required for the performance of dry laboratory tasks and the porcine nephrectomies was recorded. Errors in the performance of dry laboratory tasks of each instrument type were also recorded. Pre-bent instruments had a significant advantage over flexible instruments in terms of time requirement to accomplish tasks and procedures as well as maneuverability. Flexible instruments were more time consuming in comparison to the conventional laparoscopic instruments during the performance of the tasks. There were no significant differences in the time required for the accomplishment of dry laboratory tasks or steps of nephrectomy using conventional instruments through appropriate number of ports in comparison to pre-bent instruments through single port. Pre-bent instruments were less time consuming and with better maneuverability in comparison to flexible instruments in experimental single-port access surgery. Further clinical investigations would elucidate the efficacy of pre-bent instruments.

Modularity and hierarchical organization of action programs in children's acquisition of graphic skills.

PubMed

Manoel, Edison de J; Dantas, Luiz; Gimenez, Roberto; de Oliveira, Dalton Lustosa

2011-10-01

The organization of actions is based on modules in memory as a result of practice, easing the demand of performing more complex actions. If this modularization occurs, the elements of the module must remain invariant in new tasks. To test this hypothesis, 35 children, age 10 yr., practiced a graphic criterion task on a digital tablet and completed a complex graphic task enclosing the previous one. Total movement and pause times to draw the figure indicated skill acquisition. A module was identified by the variability of relative timing, pause time, and sequencing. Total movement to perform the criterion task did not increase significantly when it was embedded in the more complex task. Modularity was evidenced by the stability of relative timing and pause time and sequencing. The spatial position of new elements did not perturb the module, so the grammar of action may still have been forming.

A comparison of visuomotor cue integration strategies for object placement and prehension.

PubMed

Greenwald, Hal S; Knill, David C

2009-01-01

Visual cue integration strategies are known to depend on cue reliability and how rapidly the visual system processes incoming information. We investigated whether these strategies also depend on differences in the information demands for different natural tasks. Using two common goal-oriented tasks, prehension and object placement, we determined whether monocular and binocular information influence estimates of three-dimensional (3D) orientation differently depending on task demands. Both tasks rely on accurate 3D orientation estimates, but 3D position is potentially more important for grasping. Subjects placed an object on or picked up a disc in a virtual environment. On some trials, the monocular cues (aspect ratio and texture compression) and binocular cues (e.g., binocular disparity) suggested slightly different 3D orientations for the disc; these conflicts either were present upon initial stimulus presentation or were introduced after movement initiation, which allowed us to quantify how information from the cues accumulated over time. We analyzed the time-varying orientations of subjects' fingers in the grasping task and those of the object in the object placement task to quantify how different visual cues influenced motor control. In the first experiment, different subjects performed each task, and those performing the grasping task relied on binocular information more when orienting their hands than those performing the object placement task. When subjects in the second experiment performed both tasks in interleaved sessions, binocular cues were still more influential during grasping than object placement, and the different cue integration strategies observed for each task in isolation were maintained. In both experiments, the temporal analyses showed that subjects processed binocular information faster than monocular information, but task demands did not affect the time course of cue processing. How one uses visual cues for motor control depends on the task being performed, although how quickly the information is processed appears to be task invariant.

Evaluating stereoscopic displays: both efficiency measures and perceived workload sensitive to manipulations in binocular disparity

NASA Astrophysics Data System (ADS)

van Beurden, Maurice H. P. H.; Ijsselsteijn, Wijnand A.; de Kort, Yvonne A. W.

2011-03-01

Stereoscopic displays are known to offer a number of key advantages in visualizing complex 3D structures or datasets. The large majority of studies that focus on evaluating stereoscopic displays for professional applications use completion time and/or the percentage of correct answers to measure potential performance advantages. However, completion time and accuracy may not fully reflect all the benefits of stereoscopic displays. In this paper, we argue that perceived workload is an additional valuable indicator reflecting the extent to which users can benefit from using stereoscopic displays. We performed an experiment in which participants were asked to perform a visual path-tracing task within a convoluted 3D wireframe structure, varying in level of complexity of the visualised structure and level of disparity of the visualisation. The results showed that an optimal performance (completion time, accuracy and workload), depend both on task difficulty and disparity level. Stereoscopic disparity revealed a faster and more accurate task performance, whereas we observed a trend that performance on difficult tasks stands to benefit more from higher levels of disparity than performance on easy tasks. Perceived workload (as measured using the NASA-TLX) showed a similar response pattern, providing evidence that perceived workload is sensitive to variations in disparity as well as task difficulty. This suggests that perceived workload could be a useful concept, in addition to standard performance indicators, in characterising and measuring human performance advantages when using stereoscopic displays.

The Advantage of a Ureteroscopic Navigation System with Magnetic Tracking in Comparison with Simulated Fluoroscopy in a Phantom Study.

PubMed

Yoshida, Kenji; Yokomizo, Akira; Matsuda, Tadashi; Hamasaki, Tsutomu; Kondo, Yukihiro; Yamaguchi, Kunihisa; Kanayama, Hiro-Omi; Wakumoto, Yoshiaki; Horie, Shigeo; Naito, Seiji

2015-09-01

To assess whether our ureteroscopic real-time navigation system has the possibility to reduce radiation exposure and improve performance of ureteroscopic maneuvers in surgeons of various ages and experience levels. Our novel ureteroscopic navigation system used a magnetic tracking device to detect the position of the ureteroscope and display it on a three-dimensional image. We recruited 31 urologists from five institutions to perform two tasks. Task 1 consisted of finding three internal markings on the phantom calices. Task 2 consisted of identifying all calices by ureteroscopy. In both tasks, participants performed with simulated fluoroscopy first, followed by our navigation system. Accuracy rates (AR) for identification, required time (T) for completing the task, migration length (ML), and time exposed to simulated fluoroscopy were recorded. The AR, T, and ML for both tasks were significantly better with the navigation system than without it (Task 1 with simulated fluoroscopy vs with navigation: AR 87.1 % vs 98.9%, P=0.003; T 355 s vs 191 s, P<0.0001; ML 4627 mm vs 2701 mm, P<0.0001. Task 2: AR 88.2% vs 96.7%, P=0.011; T 394 s vs 333 s, P=0.027; ML 5966 mm vs 5299 mm, P=0.0006). In both tasks, the participants used the simulated fluoroscopy about 20% of the total task time. Our navigation system, while still under development, could help surgeons of all levels to achieve better performances for ureteroscopic maneuvers compared with using fluoroscopic guidance. It also has the potential to reduce radiation exposure during fluoroscopy.

Binocular Glaucomatous Visual Field Loss and Its Impact on Visual Exploration - A Supermarket Study

PubMed Central

Aehling, Kathrin; Heister, Martin; Rosenstiel, Wolfgang; Schiefer, Ulrich; Papageorgiou, Elena

2014-01-01

Advanced glaucomatous visual field loss may critically interfere with quality of life. The purpose of this study was to (i) assess the impact of binocular glaucomatous visual field loss on a supermarket search task as an example of everyday living activities, (ii) to identify factors influencing the performance, and (iii) to investigate the related compensatory mechanisms. Ten patients with binocular glaucoma (GP), and ten healthy-sighted control subjects (GC) were asked to collect twenty different products chosen randomly in two supermarket racks as quickly as possible. The task performance was rated as “passed” or “failed” with regard to the time per correctly collected item. Based on the performance of control subjects, the threshold value for failing the task was defined as μ+3σ (in seconds per correctly collected item). Eye movements were recorded by means of a mobile eye tracker. Eight out of ten patients with glaucoma and all control subjects passed the task. Patients who failed the task needed significantly longer time (111.47 s ±12.12 s) to complete the task than patients who passed (64.45 s ±13.36 s, t-test, p<0.001). Furthermore, patients who passed the task showed a significantly higher number of glances towards the visual field defect (VFD) area than patients who failed (t-test, p<0.05). According to these results, glaucoma patients with defects in the binocular visual field display on average longer search times in a naturalistic supermarket task. However, a considerable number of patients, who compensate by frequent glancing towards the VFD, showed successful task performance. Therefore, systematic exploration of the VFD area seems to be a “time-effective” compensatory mechanism during the present supermarket task. PMID:25162522

Binocular glaucomatous visual field loss and its impact on visual exploration--a supermarket study.

PubMed

Sippel, Katrin; Kasneci, Enkelejda; Aehling, Kathrin; Heister, Martin; Rosenstiel, Wolfgang; Schiefer, Ulrich; Papageorgiou, Elena

2014-01-01

Advanced glaucomatous visual field loss may critically interfere with quality of life. The purpose of this study was to (i) assess the impact of binocular glaucomatous visual field loss on a supermarket search task as an example of everyday living activities, (ii) to identify factors influencing the performance, and (iii) to investigate the related compensatory mechanisms. Ten patients with binocular glaucoma (GP), and ten healthy-sighted control subjects (GC) were asked to collect twenty different products chosen randomly in two supermarket racks as quickly as possible. The task performance was rated as "passed" or "failed" with regard to the time per correctly collected item. Based on the performance of control subjects, the threshold value for failing the task was defined as μ+3σ (in seconds per correctly collected item). Eye movements were recorded by means of a mobile eye tracker. Eight out of ten patients with glaucoma and all control subjects passed the task. Patients who failed the task needed significantly longer time (111.47 s ±12.12 s) to complete the task than patients who passed (64.45 s ±13.36 s, t-test, p < 0.001). Furthermore, patients who passed the task showed a significantly higher number of glances towards the visual field defect (VFD) area than patients who failed (t-test, p < 0.05). According to these results, glaucoma patients with defects in the binocular visual field display on average longer search times in a naturalistic supermarket task. However, a considerable number of patients, who compensate by frequent glancing towards the VFD, showed successful task performance. Therefore, systematic exploration of the VFD area seems to be a "time-effective" compensatory mechanism during the present supermarket task.

Age-related differences in time-based prospective memory: The role of time estimation in the clock monitoring strategy.

PubMed

Vanneste, Sandrine; Baudouin, Alexia; Bouazzaoui, Badiâa; Taconnat, Laurence

2016-07-01

Time-based prospective memory (TBPM) is required when it is necessary to remember to perform an action at a specific future point in time. This type of memory has been found to be particularly sensitive to ageing, probably because it requires a self-initiated response at a specific time. In this study, we sought to examine the involvement of temporal processes in the time monitoring strategy, which has been demonstrated to be a decisive factor in TBPM efficiency. We compared the performance of young and older adults in a TBPM task in which they had to press a response button every minute while categorising words. The design allowed participants to monitor time by checking a clock whenever they decided. Participants also completed a classic time-production task and several executive tasks assessing inhibition, updating and shifting processes. Our results confirm an age-related lack of accuracy in prospective memory performance, which seems to be related to a deficient strategic use of time monitoring. This could in turn be partially explained by age-related temporal deficits, as evidenced in the duration production task. These findings suggest that studies designed to investigate the age effect in TBPM tasks should consider the contribution of temporal mechanisms.

Human performance in a multiple-task environment: effects of automation reliability on visual attention allocation.

PubMed

Cullen, Ralph H; Rogers, Wendy A; Fisk, Arthur D

2013-11-01

Diagnostic automation has been posited to alleviate the high demands of multiple-task environments; however, mixed effects have been found pertaining to performance aid success. To better understand these effects, attention allocation must be studied directly. We developed a multiple-task environment to study the effects of automation on visual attention. Participants interacted with a system providing varying levels of automation and automation reliability and then were transferred to a system with no support. Attention allocation was measured by tracking the number of times each task was viewed. We found that participants receiving automation allocated their time according to the task frequency and that tasks that benefited most from automation were most harmed when it was removed. The results suggest that the degree to which automation affects multiple-task performance is dependent on the relative attributes of the tasks involved. Moreover, there is an inverse relationship between support and cost when automation fails. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Cognitive Performance and Heart Rate Variability: The Influence of Fitness Level

PubMed Central

Luque-Casado, Antonio; Zabala, Mikel; Morales, Esther; Mateo-March, Manuel; Sanabria, Daniel

2013-01-01

In the present study, we investigated the relation between cognitive performance and heart rate variability as a function of fitness level. We measured the effect of three cognitive tasks (the psychomotor vigilance task, a temporal orienting task, and a duration discrimination task) on the heart rate variability of two groups of participants: a high-fit group and a low-fit group. Two major novel findings emerged from this study. First, the lowest values of heart rate variability were found during performance of the duration discrimination task, compared to the other two tasks. Second, the results showed a decrement in heart rate variability as a function of the time on task, although only in the low-fit group. Moreover, the high-fit group showed overall faster reaction times than the low-fit group in the psychomotor vigilance task, while there were not significant differences in performance between the two groups of participants in the other two cognitive tasks. In sum, our results highlighted the influence of cognitive processing on heart rate variability. Importantly, both behavioral and physiological results suggested that the main benefit obtained as a result of fitness level appeared to be associated with processes involving sustained attention. PMID:23437276

The impact of crosstalk on three-dimensional laparoscopic performance and workload.

PubMed

Sakata, Shinichiro; Grove, Philip M; Watson, Marcus O; Stevenson, Andrew R L

2017-10-01

This is the first study to explore the effects of crosstalk from 3D laparoscopic displays on technical performance and workload. We studied crosstalk at magnitudes that may have been tolerated during laparoscopic surgery. Participants were 36 voluntary doctors. To minimize floor effects, participants completed their surgery rotations, and a laparoscopic suturing course for surgical trainees. We used a counterbalanced, within-subjects design in which participants were randomly assigned to complete laparoscopic tasks in one of six unique testing sequences. In a simulation laboratory, participants were randomly assigned to complete laparoscopic 'navigation in space' and suturing tasks in three viewing conditions: 2D, 3D without ghosting and 3D with ghosting. Participants calibrated their exposure to crosstalk as the maximum level of ghosting that they could tolerate without discomfort. The Randot® Stereotest was used to verify stereoacuity. The study performance metric was time to completion. The NASA TLX was used to measure workload. Normal threshold stereoacuity (40-20 second of arc) was verified in all participants. Comparing optimal 3D with 2D viewing conditions, mean performance times were 2.8 and 1.6 times faster in laparoscopic navigation in space and suturing tasks respectively (p< .001). Comparing optimal 3D with suboptimal 3D viewing conditions, mean performance times were 2.9 times faster in both tasks (p< .001). Mean workload in 2D was 1.5 and 1.3 times greater than in optimal 3D viewing, for navigation in space and suturing tasks respectively (p< .001). Mean workload associated with suboptimal 3D was 1.3 times greater than optimal 3D in both laparoscopic tasks (p< .001). There was no significant relationship between the magnitude of ghosting score, laparoscopic performance and workload. Our findings highlight the advantages of 3D displays when used optimally, and their shortcomings when used sub-optimally, on both laparoscopic performance and workload.

Human task animation from performance models and natural language input

NASA Technical Reports Server (NTRS)

Esakov, Jeffrey; Badler, Norman I.; Jung, Moon

1989-01-01

Graphical manipulation of human figures is essential for certain types of human factors analyses such as reach, clearance, fit, and view. In many situations, however, the animation of simulated people performing various tasks may be based on more complicated functions involving multiple simultaneous reaches, critical timing, resource availability, and human performance capabilities. One rather effective means for creating such a simulation is through a natural language description of the tasks to be carried out. Given an anthropometrically-sized figure and a geometric workplace environment, various simple actions such as reach, turn, and view can be effectively controlled from language commands or standard NASA checklist procedures. The commands may also be generated by external simulation tools. Task timing is determined from actual performance models, if available, such as strength models or Fitts' Law. The resulting action specification are animated on a Silicon Graphics Iris workstation in real-time.

Cognitive and motor dual task gait training improve dual task gait performance after stroke - A randomized controlled pilot trial.

PubMed

Liu, Yan-Ci; Yang, Yea-Ru; Tsai, Yun-An; Wang, Ray-Yau

2017-06-22

This study investigated effects of cognitive and motor dual task gait training on dual task gait performance in stroke. Participants (n = 28) were randomly assigned to cognitive dual task gait training (CDTT), motor dual task gait training (MDTT), or conventional physical therapy (CPT) group. Participants in CDTT or MDTT group practiced the cognitive or motor tasks respectively during walking. Participants in CPT group received strengthening, balance, and gait training. The intervention was 30 min/session, 3 sessions/week for 4 weeks. Three test conditions to evaluate the training effects were single walking, walking while performing cognitive task (serial subtraction), and walking while performing motor task (tray-carrying). Parameters included gait speed, dual task cost of gait speed (DTC-speed), cadence, stride time, and stride length. After CDTT, cognitive-motor dual task gait performance (stride length and DTC-speed) was improved (p = 0.021; p = 0.015). After MDTT, motor dual task gait performance (gait speed, stride length, and DTC-speed) was improved (p = 0.008; p = 0.008; p = 0.008 respectively). It seems that CDTT improved cognitive dual task gait performance and MDTT improved motor dual task gait performance although such improvements did not reach significant group difference. Therefore, different types of dual task gait training can be adopted to enhance different dual task gait performance in stroke.

Motor Timing Deficits in Sequential Movements in Parkinson Disease Are Related to Action Planning: A Motor Imagery Study

PubMed Central

Avanzino, Laura; Pelosin, Elisa; Martino, Davide; Abbruzzese, Giovanni

2013-01-01

Timing of sequential movements is altered in Parkinson disease (PD). Whether timing deficits in internally generated sequential movements in PD depends also on difficulties in motor planning, rather than merely on a defective ability to materially perform the planned movement is still undefined. To unveil this issue, we adopted a modified version of an established test for motor timing, i.e. the synchronization–continuation paradigm, by introducing a motor imagery task. Motor imagery is thought to involve mainly processes of movement preparation, with reduced involvement of end-stage movement execution-related processes. Fourteen patients with PD and twelve matched healthy volunteers were asked to tap in synchrony with a metronome cue (SYNC) and then, when the tone stopped, to keep tapping, trying to maintain the same rhythm (CONT-EXE) or to imagine tapping at the same rhythm, rather than actually performing it (CONT-MI). We tested both a sub-second and a supra-second inter-stimulus interval between the cues. Performance was recorded using a sensor-engineered glove and analyzed measuring the temporal error and the interval reproduction accuracy index. PD patients were less accurate than healthy subjects in the supra-second time reproduction task when performing both continuation tasks (CONT-MI and CONT-EXE), whereas no difference was detected in the synchronization task and on all tasks involving a sub-second interval. Our findings suggest that PD patients exhibit a selective deficit in motor timing for sequential movements that are separated by a supra-second interval and that this deficit may be explained by a defect of motor planning. Further, we propose that difficulties in motor planning are of a sufficient degree of severity in PD to affect also the motor performance in the supra-second time reproduction task. PMID:24086534

Involvement of the anterior cingulate cortex in time-based prospective memory task monitoring: An EEG analysis of brain sources using Independent Component and Measure Projection Analysis

PubMed Central

Burgos, Pablo; Kilborn, Kerry; Evans, Jonathan J.

2017-01-01

Objective Time-based prospective memory (PM), remembering to do something at a particular moment in the future, is considered to depend upon self-initiated strategic monitoring, involving a retrieval mode (sustained maintenance of the intention) plus target checking (intermittent time checks). The present experiment was designed to explore what brain regions and brain activity are associated with these components of strategic monitoring in time-based PM tasks. Method 24 participants were asked to reset a clock every four minutes, while performing a foreground ongoing word categorisation task. EEG activity was recorded and data were decomposed into source-resolved activity using Independent Component Analysis. Common brain regions across participants, associated with retrieval mode and target checking, were found using Measure Projection Analysis. Results Participants decreased their performance on the ongoing task when concurrently performed with the time-based PM task, reflecting an active retrieval mode that relied on withdrawal of limited resources from the ongoing task. Brain activity, with its source in or near the anterior cingulate cortex (ACC), showed changes associated with an active retrieval mode including greater negative ERP deflections, decreased theta synchronization, and increased alpha suppression for events locked to the ongoing task while maintaining a time-based intention. Activity in the ACC was also associated with time-checks and found consistently across participants; however, we did not find an association with time perception processing per se. Conclusion The involvement of the ACC in both aspects of time-based PM monitoring may be related to different functions that have been attributed to it: strategic control of attention during the retrieval mode (distributing attentional resources between the ongoing task and the time-based task) and anticipatory/decision making processing associated with clock-checks. PMID:28863146

The effect of pain on task switching: pain reduces accuracy and increases reaction times across multiple switching paradigms.

PubMed

Attridge, Nina; Keogh, Edmund; Eccleston, Christopher

2016-10-01

Pain disrupts attention, which may have negative consequences for daily life for people with acute or chronic pain. It has been suggested that switching between tasks may leave us particularly susceptible to pain-related attentional disruption, because we need to disengage our attention from one task before shifting it onto another. Switching tasks typically elicit lower accuracies and/or longer reaction times when participants switch to a new task compared with repeating the same task, and pain may exacerbate this effect. We present 3 studies to test this hypothesis. In study 1, participants completed 2 versions of an alternating runs switching task under pain-free and thermal pain-induction conditions. Pain did not affect performance on either task. In studies 2 and 3, we examined 7 versions of the switching task using large general population samples, experiencing a variety of naturally occurring pain conditions, recruited and tested on the internet. On all tasks, participants with pain had longer reaction times on both switch and repeat trials compared with participants without pain, but pain did not increase switch costs. In studies 2 and 3, we also investigated the effects of type of pain, duration of pain, and analgesics on task performance. We conclude that pain has a small dampening effect on performance overall on switching tasks. This suggests that pain interrupts attention even when participants are engaged in a trial, not only when attention has been disengaged for shifting to a new task set.

Motor demands impact speed of information processing in Autism Spectrum Disorders

PubMed Central

Kenworthy, Lauren; Yerys, Benjamin E.; Weinblatt, Rachel; Abrams, Danielle N.; Wallace, Gregory L.

2015-01-01

Objective The apparent contradiction between preserved or even enhanced perceptual processing speed on inspection time tasks in autism spectrum disorders (ASD) and impaired performance on complex processing speed tasks that require motor output (e.g. Wechsler Processing Speed Index) has not yet been systematically investigated. This study investigates whether adding motor output demands to an inspection time task impairs ASD performance compared to that of typically developing control (TDC) children. Method The performance of children with ASD (n=28; mean FSIQ=115) and TDC (n=25; mean FSIQ=122) children was compared on processing speed tasks with increasing motor demand. Correlations were run between ASD task performance and Autism Diagnostic Observation Schedule (ADOS) Communication scores. Results Performance by the ASD and TDC groups on a simple perceptual processing speed task with minimal motor demand was equivalent, though it diverged (ASD worse than TDC) on two tasks with the same stimuli, but increased motor output demands. ASD performance on the moderate but not the high speeded motor output demand task was negatively correlated with ADOS communication symptoms. Conclusions These data address the apparent contradiction between preserved inspection time in the context of slowed “processing speed” in ASD. They show that processing speed is preserved when motor demands are minimized, but that increased motor output demands interfere with the ability to act on perceptual processing of simple stimuli. Reducing motor demands (e.g. through the use of computers) may increase the capacity of people with ASD to demonstrate good perceptual processing in a variety of educational, vocational and social settings. PMID:23937483

Evaluation of telerobotic systems using an instrumented task board

NASA Technical Reports Server (NTRS)

Carroll, John D.; Gierow, Paul A.; Bryan, Thomas C.

1991-01-01

An instrumented task board was developed at NASA Marshall Space Flight Center (MSFC). An overview of the task board design, and current development status is presented. The task board was originally developed to evaluate operator performance using the Protoflight Manipulator Arm (PFMA) at MSFC. The task board evaluates tasks for Orbital Replacement Unit (ORU), fluid connect and transfers, electrical connect/disconnect, bolt running, and other basic tasks. The instrumented task board measures the 3-D forces and torques placed on the board, determines the robot arm's 3-D position relative to the task board using IR optics, and provides the information in real-time. The PFMA joint input signals can also be measured from a breakout box to evaluate the sensitivity or response of the arm operation to control commands. The data processing system provides the capability for post processing of time-history graphics and plots of the PFMA positions, the operator's actions, and the PFMA servo reactions in addition to real-time force/torque data presentation. The instrumented task board's most promising use is developing benchmarks for NASA centers for comparison and evaluation of telerobotic performance.

Approximate Number Sense, Symbolic Number Processing, or Number-Space Mappings: What Underlies Mathematics Achievement?

ERIC Educational Resources Information Center

Sasanguie, Delphine; Gobel, Silke M.; Moll, Kristina; Smets, Karolien; Reynvoet, Bert

2013-01-01

In this study, the performance of typically developing 6- to 8-year-old children on an approximate number discrimination task, a symbolic comparison task, and a symbolic and nonsymbolic number line estimation task was examined. For the first time, children's performances on these basic cognitive number processing tasks were explicitly contrasted…

Hyperoxia and Hypoxic Hypoxia Effects on Simple and Choice Reaction Times.

PubMed

Dart, Todd; Gallo, Megan; Beer, Jeremy; Fischer, Joseph; Morgan, Thomas; Pilmanis, Andrew

2017-12-01

Effects of exposure to hyperoxia (PiO2 > 105 mmHg), normoxia (PiO2 95-105 mmHg) and hypoxia (PiO2 < 95 mmHg) on simple and choice reaction performance tasks were evaluated. Ten subjects performed simple and choice reaction time tests (SRT and CRT, respectively) at ground level for 40 min (20 min normoxic, 20 min hyperoxic, randomly assigned), 3048 m (10,000 ft) for 75 min (15 min hyperoxic, 60 min hypoxic), 4572 m (15,000 ft) for 60 min (15 min hyperoxic, 45 min hypoxic), and 6096 m (20,000 ft) for 35 min (15 min hyperoxic, 20 min hypoxic). SRT and CRT tests were also conducted at ground level 1 h after normoxic rest (recovery) to assess any recovery time effect on these psychomotor tasks. Total response time (TRT) significantly increased by 15 ms to 25 ms at all three altitudes for both the SRT and CRT tasks. At and below 4572 m, the performance changes were gradual over the duration of the exposures, whereas at 6096 m these changes were immediate. After 1 h, no performance decrement was measured. There was no statistical evidence that ground-level performance on these tasks was improved in hyperoxic vs. normoxic conditions. Results suggest mild decrements in reaction time due to hypoxia may occur as low as 3048 m (10,000 ft) while hyperoxia showed no positive effect on accuracy or reaction time at ground level or higher when performing simple and choice psychomotor reaction tasks.Dart T, Gallo M, Beer J, Fischer J, Morgan T, Pilmanis A. Hyperoxia and hypoxic hypoxia effects on simple and choice reaction times. Aerosp Med Hum Perform. 2017; 88(12):1073-1080.

Interval timing in children: effects of auditory and visual pacing stimuli and relationships with reading and attention variables.

PubMed

Birkett, Emma E; Talcott, Joel B

2012-01-01

Motor timing tasks have been employed in studies of neurodevelopmental disorders such as developmental dyslexia and ADHD, where they provide an index of temporal processing ability. Investigations of these disorders have used different stimulus parameters within the motor timing tasks that are likely to affect performance measures. Here we assessed the effect of auditory and visual pacing stimuli on synchronised motor timing performance and its relationship with cognitive and behavioural predictors that are commonly used in the diagnosis of these highly prevalent developmental disorders. Twenty-one children (mean age 9.6 years) completed a finger tapping task in two stimulus conditions, together with additional psychometric measures. As anticipated, synchronisation to the beat (ISI 329 ms) was less accurate in the visually paced condition. Decomposition of timing variance indicated that this effect resulted from differences in the way that visual and auditory paced tasks are processed by central timekeeping and associated peripheral implementation systems. The ability to utilise an efficient processing strategy on the visual task correlated with both reading and sustained attention skills. Dissociations between these patterns of relationship across task modality suggest that not all timing tasks are equivalent.

EEG alpha spindles and prolonged brake reaction times during auditory distraction in an on-road driving study.

PubMed

Sonnleitner, Andreas; Treder, Matthias Sebastian; Simon, Michael; Willmann, Sven; Ewald, Arne; Buchner, Axel; Schrauf, Michael

2014-01-01

Driver distraction is responsible for a substantial number of traffic accidents. This paper describes the impact of an auditory secondary task on drivers' mental states during a primary driving task. N=20 participants performed the test procedure in a car following task with repeated forced braking on a non-public test track. Performance measures (provoked reaction time to brake lights) and brain activity (EEG alpha spindles) were analyzed to describe distracted drivers. Further, a classification approach was used to investigate whether alpha spindles can predict drivers' mental states. Results show that reaction times and alpha spindle rate increased with time-on-task. Moreover, brake reaction times and alpha spindle rate were significantly higher while driving with auditory secondary task opposed to driving only. In single-trial classification, a combination of spindle parameters yielded a median classification error of about 8% in discriminating the distracted from the alert driving. Reduced driving performance (i.e., prolonged brake reaction times) during increased cognitive load is assumed to be indicated by EEG alpha spindles, enabling the quantification of driver distraction in experiments on public roads without verbally assessing the drivers' mental states. Copyright © 2013 Elsevier Ltd. All rights reserved.

Blinks, saccades, and fixation pauses during vigilance task performance. II., Gender and time of day.

DOT National Transportation Integrated Search

1996-03-01

As operators are required to spend more time monitoring computer controlled devices in future systems, it is critical to define the task and situational factors (i.e., fatigue) that may impact vigilance and performance. Aspects of the gaze system can...

Finger tapping and pre-attentive sensorimotor timing in adults with ADHD.

PubMed

Hove, Michael J; Gravel, Nickolas; Spencer, Rebecca M C; Valera, Eve M

2017-12-01

Sensorimotor timing deficits are considered central to attention-deficit/hyperactivity disorder (ADHD). However, the tasks establishing timing impairments often involve interconnected processes, including low-level sensorimotor timing and higher level executive processes such as attention. Thus, the source of timing deficits in ADHD remains unclear. Low-level sensorimotor timing can be isolated from higher level processes in a finger-tapping task that examines the motor response to unexpected shifts of metronome onsets. In this study, adults with ADHD and ADHD-like symptoms (n = 25) and controls (n = 26) performed two finger-tapping tasks. The first assessed tapping variability in a standard tapping task (metronome-paced and unpaced). In the other task, participants tapped along with a metronome that contained unexpected shifts (±15, 50 ms); the timing adjustment on the tap following the shift captures pre-attentive sensorimotor timing (i.e., phase correction) and thus should be free of potential higher order confounds (e.g., attention). In the standard tapping task, as expected, the ADHD group had higher timing variability in both paced and unpaced tappings. However, in the pre-attentive task, performance did not differ between the ADHD and control groups. Together, results suggest that low-level sensorimotor timing and phase correction are largely preserved in ADHD and that some timing impairments observed in ADHD may stem from higher level factors (such as sustained attention).

Performance on a virtual reality angled laparoscope task correlates with spatial ability of trainees.

PubMed

Rosenthal, Rachel; Hamel, Christian; Oertli, Daniel; Demartines, Nicolas; Gantert, Walter A

2010-08-01

The aim of the present study was to investigate whether trainees' performance on a virtual reality angled laparoscope navigation task correlates with scores obtained on a validated conventional test of spatial ability. 56 participants of a surgery workshop performed an angled laparoscope navigation task on the Xitact LS 500 virtual reality Simulator. Performance parameters were correlated with the score of a validated paper-and-pencil test of spatial ability. Performance at the conventional spatial ability test significantly correlated with performance at the virtual reality task for overall task score (p < 0.001), task completion time (p < 0.001) and economy of movement (p = 0.035), not for endoscope travel speed (p = 0.947). In conclusion, trainees' performance in a standardized virtual reality camera navigation task correlates with their innate spatial ability. This VR session holds potential to serve as an assessment tool for trainees.

The effects of timing of exposure to principles and procedural instruction specificity on learning an electrical troubleshooting skill.

PubMed

Eiriksdottir, Elsa; Catrambone, Richard

2015-12-01

Domain principles provided in task instructions are assumed to help performance as learners can later apply this knowledge when faced with new tasks. The goal of the research was to investigate whether the timing of the exposure to principles-studying the principles before or while completing training tasks-and the specificity in the accompanying step-by-step procedural instructions would influence learning to troubleshoot a simulated electrical circuit. The results of a pilot study suggested that timing of principle exposure and specificity might interact. This was investigated by comparing the performance of 4 groups of participants (n = 24) who received either general or detailed procedural instructions and were either exposed to the principles before or during the training. The results showed that studying the principles before training benefited test task performance when the procedural instructions were detailed but not when they were general. The results also showed that using general procedural instructions benefited test task performance while using detailed procedural instructions benefited training task performance. Overall the results reveal how the learning situation as a whole must be considered when determining the efficacy of instructional materials, and how conditions can be created where principles enhance learning. (c) 2015 APA, all rights reserved).

Age-related differences in listening effort during degraded speech recognition

PubMed Central

Ward, Kristina M.; Shen, Jing; Souza, Pamela E.; Grieco-Calub, Tina M.

2016-01-01

Objectives The purpose of the current study was to quantify age-related differences in executive control as it relates to dual-task performance, which is thought to represent listening effort, during degraded speech recognition. Design Twenty-five younger adults (18–24 years) and twenty-one older adults (56–82 years) completed a dual-task paradigm that consisted of a primary speech recognition task and a secondary visual monitoring task. Sentence material in the primary task was either unprocessed or spectrally degraded into 8, 6, or 4 spectral channels using noise-band vocoding. Performance on the visual monitoring task was assessed by the accuracy and reaction time of participants’ responses. Performance on the primary and secondary task was quantified in isolation (i.e., single task) and during the dual-task paradigm. Participants also completed a standardized psychometric measure of executive control, including attention and inhibition. Statistical analyses were implemented to evaluate changes in listeners’ performance on the primary and secondary tasks (1) per condition (unprocessed vs. vocoded conditions); (2) per task (baseline vs. dual task); and (3) per group (younger vs. older adults). Results Speech recognition declined with increasing spectral degradation for both younger and older adults when they performed the task in isolation or concurrently with the visual monitoring task. Older adults were slower and less accurate than younger adults on the visual monitoring task when performed in isolation, which paralleled age-related differences in standardized scores of executive control. When compared to single-task performance, older adults experienced greater declines in secondary-task accuracy, but not reaction time, than younger adults. Furthermore, results revealed that age-related differences in executive control significantly contributed to age-related differences on the visual monitoring task during the dual-task paradigm. Conclusions Older adults experienced significantly greater declines in secondary-task accuracy during degraded speech recognition than younger adults. These findings are interpreted as suggesting that older listeners expended greater listening effort than younger listeners, and may be partially attributed to age-related differences in executive control. PMID:27556526

Experimental evaluation of the concept of supevisory manipulation

NASA Technical Reports Server (NTRS)

Brooks, T. L.; Sheridan, T. B.

1982-01-01

A computer-controlled teleoperator system which is based on task-referenced sensor-aided control has been developed to study supervisory manipulation. This system, called SUPERMAN, is capable of performing complicated tasks in real-time by utilizing the operator for high-level functions related to the unpredictable portions of a task, while the subordinate machine performs the more well-defined subtasks under human supervison. To determine whether supervisory control schemes such as these offer any advantage over manual control under real-time conditions, a number of experiments involving both simple and complicated tasks were performed. Six representative tasks were chosen for the study: (1) obtaining a tool from a rack, (2) returning the tool to the rack, (3) removing a nut, (4) placing samples in a storage bin, (5) opening and closing a valve, and (6) digging with a shovel. The experiments were performed under simulated conditions using four forms of manual control (i.e., switch rate, joystick rate, master-slave position control, and master-slave with force feedback), as well as supervisory control. Through these experiments the effectiveness and quality of control were evaluated on the basis of the time required to complete each portion of the task and the type and number of errors which occurred.

Time and motion studies of National Health Service cataract theatre lists to determine strategies to improve efficiency.

PubMed

Roberts, Harry W; Myerscough, James; Borsci, Simone; Ni, Melody; O'Brart, David P S

2017-11-24

To provide a quantitative assessment of cataract theatre lists focusing on productivity and staffing levels/tasks using time and motion studies. National Health Service (NHS) cataract theatre lists were prospectively observed in five different institutions (four NHS hospitals and one private hospital). Individual tasks and their timings of every member of staff were recorded. Multiple linear regression analyses were performed to investigate possible associations between individual timings and tasks. 140 operations were studied over 18 theatre sessions. The median number of scheduled cataract operations was 7 (range: 5-14). The average duration of an operation was 10.3 min±(SD 4.11 min). The average time to complete one case including patient turnaround was 19.97 min (SD 8.77 min). The proportion of the surgeons' time occupied on total duties or operating ranged from 65.2% to 76.1% and from 42.4% to 56.7%, respectively. The correlations of the surgical time to patient time in theatre was R 2 =0.95. A multiple linear regression model found a significant association (F(3,111)=32.86, P<0.001) with R 2 =0.47 between the duration of one operation and the number of allied healthcare professionals (AHPs), the number of AHP key tasks and the time taken to perform these key tasks by the AHPs. Significant variability in the number of cases performed and the efficiency of patient flow were found between different institutions. Time and motion studies identified requirements for high-volume models and factors relating to performance. Supporting the surgeon with sufficient AHPs and tasks performed by AHPs could improve surgical efficiency up to approximately double productivity over conventional theatre models. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Stress in nonregular work arrangements: A longitudinal study of task- and employment-related aspects of stress.

PubMed

Vahle-Hinz, Tim

2016-10-01

In nonregular forms of employment, such as fixed-term or temporary agency work, 2 sources of stress must be distinguished: task-related stress components (e.g., time pressure) and employment-related stress components (e.g., effort to maintain employment). The present study investigated the relationship between task- and employment-related demands and resources and indicators of strain, well-being, work engagement, and self-rated performance in a sample of nonregular employed workers. Using a 2-wave longitudinal design, the results of autoregressive cross-lagged structural equation models demonstrated that time pressure, as a task-related demand, is positively related to strain and negatively related to well-being and self-rated performance. Autonomy, as a task-related resource, exhibited no significant relationships in the current study. Employment-related demands exhibited negative relationships with well-being and work engagement as well as negative and positive relationships with self-rated performance over time. Employment-related resources were primarily positive predictors of well-being and self-rated performance. Fit indices of comparative models indicated that reciprocal effect models (which enable causal and reverse effects) best fit the data. Accordingly, demands and resources predicted strain, well-being, work engagement, and self-rated performance over time and vice versa. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Differences in day and night shift clinical performance in anesthesiology.

PubMed

Cao, Caroline G L; Weinger, Matthew B; Slagle, Jason; Zhou, Chuan; Ou, Jennie; Gillin, Shakha; Sheh, Bryant; Mazzei, William

2008-04-01

This study examined whether anesthesia residents (physicians in training) performed clinical duties in the operating room differently during the day versus at night. Fatigue from sleep deprivation and working through the night is common for physicians, particularly during residency training. Using a repeated-measures design, we studied 13 pairs of day-night matched anesthesia cases. Dependent measures included task times, workload ratings, response to an alarm light latency task, and mood. Residents spent significantly less time on manual tasks and more time on monitoring tasks during the maintenance phase at night than during the day. Residents reported more negative mood at night than during the day, both pre- and postoperation. However, time of day had no effect on the mood change between pre- and postoperation. Workload ratings and the response time to an alarm light latency task were not significantly different between night and day cases. Because night shift residents had been awake and working for more than 16 hr, the observed differences in task performance and mood may be attributed to fatigue. The changes in task distribution during night shift work may represent compensatory strategies to maintain patient care quality while keeping perceived workload at a manageable level. Fatigue effects during night shifts should be considered when designing work-rest schedules for clinicians. This matched-case control scheme can also be applied to study other phenomena associated with patient safety in the actual clinical environment.

Driver Vigilance in Automated Vehicles: Hazard Detection Failures Are a Matter of Time.

PubMed

Greenlee, Eric T; DeLucia, Patricia R; Newton, David C

2018-06-01

The primary aim of the current study was to determine whether monitoring the roadway for hazards during automated driving results in a vigilance decrement. Although automated vehicles are relatively novel, the nature of human-automation interaction within them has the classic hallmarks of a vigilance task. Drivers must maintain attention for prolonged periods of time to detect and respond to rare and unpredictable events, for example, roadway hazards that automation may be ill equipped to detect. Given the similarity with traditional vigilance tasks, we predicted that drivers of a simulated automated vehicle would demonstrate a vigilance decrement in hazard detection performance. Participants "drove" a simulated automated vehicle for 40 minutes. During that time, their task was to monitor the roadway for roadway hazards. As predicted, hazard detection rate declined precipitously, and reaction times slowed as the drive progressed. Further, subjective ratings of workload and task-related stress indicated that sustained monitoring is demanding and distressing and it is a challenge to maintain task engagement. Monitoring the roadway for potential hazards during automated driving results in workload, stress, and performance decrements similar to those observed in traditional vigilance tasks. To the degree that vigilance is required of automated vehicle drivers, performance errors and associated safety risks are likely to occur as a function of time on task. Vigilance should be a focal safety concern in the development of vehicle automation.

Prospective memory in context: Moving through a familiar space.

PubMed

Smith, Rebekah E; Hunt, R Reed; Murray, Amy E

2017-02-01

Successful completion of delayed intentions is a common but important aspect of daily behavior. Such behavior requires not only memory for the intended action but also recognition of the opportunity to perform that action, known collectively as prospective memory. The fact that prospective memory tasks occur in the midst of other activities is captured in laboratory tasks by embedding the prospective memory task in an ongoing activity. In many cases the requirement to perform the prospective memory task results in a reduction in ongoing performance relative to when the ongoing task is performed alone. This is referred to as the cost to the ongoing task and reflects the allocation of attentional resources to the prospective memory task. The current study examined the pattern of cost across the ongoing task when the ongoing task provided contextual information that in turn allowed participants to anticipate when target events would occur within the ongoing task. The availability of contextual information reduced ongoing task response times overall, with an increase in response times closer to the target locations (Experiments 1-3). The fourth study, drawing on the Event Segmentation Theory, provided support for the proposal made by the Preparatory Attentional and Memory Processes theory of prospective memory that decisions about the allocation of attention to the prospective memory task are more likely to be made at points of transition. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Measures of Time-Sharing Skill and Gender as Predictors of Flight Simulator Performance.

DTIC Science & Technology

1979-01-01

well as overall e- quations including gender as a variable. Besides gender in the overall equations, measures of time-sharing skill were the best ...study indicated the best predictors of dual or whole-task performance were other dual-tasks. Furthermore, the particular components involved in a dual...switching between tasks, or the use of efficient response strategies " (Damos and Wickens, 1977, p.2). Attentional flexibility. According to Keele

Reliability and Validity of Dual-Task Mobility Assessments in People with Chronic Stroke

PubMed Central

Yang, Lei; He, Chengqi; Pang, Marco Yiu Chung

2016-01-01

Background The ability to perform a cognitive task while walking simultaneously (dual-tasking) is important in real life. However, the psychometric properties of dual-task walking tests have not been well established in stroke. Objective To assess the test-retest reliability, concurrent and known-groups validity of various dual-task walking tests in people with chronic stroke. Design Observational measurement study with a test-retest design. Methods Eighty-eight individuals with chronic stroke participated. The testing protocol involved four walking tasks (walking forward at self-selected and maximal speed, walking backward at self-selected speed, and crossing over obstacles) performed simultaneously with each of the three attention-demanding tasks (verbal fluency, serial 3 subtractions or carrying a cup of water). For each dual-task condition, the time taken to complete the walking task, the correct response rate (CRR) of the cognitive task, and the dual-task effect (DTE) for the walking time and CRR were calculated. Forty-six of the participants were tested twice within 3–4 days to establish test-retest reliability. Results The walking time in various dual-task assessments demonstrated good to excellent reliability [Intraclass correlation coefficient (ICC2,1) = 0.70–0.93; relative minimal detectable change at 95% confidence level (MDC95%) = 29%-45%]. The reliability of the CRR (ICC2,1 = 0.58–0.81) and the DTE in walking time (ICC2,1 = 0.11–0.80) was more varied. The reliability of the DTE in CRR (ICC2,1 = -0.31–0.40) was poor to fair. The walking time and CRR obtained in various dual-task walking tests were moderately to strongly correlated with those of the dual-task Timed-up-and-Go test, thus demonstrating good concurrent validity. None of the tests could discriminate fallers (those who had sustained at least one fall in the past year) from non-fallers. Limitation The results are generalizable to community-dwelling individuals with chronic stroke only. Conclusions The walking time derived from the various dual-task assessments generally demonstrated good to excellent reliability, making them potentially useful in clinical practice and future research endeavors. However, the usefulness of these measurements in predicting falls needs to be further explored. Relatively low reliability was shown in the cognitive outcomes and DTE, which may not be preferred measurements for assessing dual-task performance. PMID:26808662

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.

Task-discriminative space-by-time factorization of muscle activity

PubMed Central

Delis, Ioannis; Panzeri, Stefano; Pozzo, Thierry; Berret, Bastien

2015-01-01

Movement generation has been hypothesized to rely on a modular organization of muscle activity. Crucial to this hypothesis is the ability to perform reliably a variety of motor tasks by recruiting a limited set of modules and combining them in a task-dependent manner. Thus far, existing algorithms that extract putative modules of muscle activations, such as Non-negative Matrix Factorization (NMF), identify modular decompositions that maximize the reconstruction of the recorded EMG data. Typically, the functional role of the decompositions, i.e., task accomplishment, is only assessed a posteriori. However, as motor actions are defined in task space, we suggest that motor modules should be computed in task space too. In this study, we propose a new module extraction algorithm, named DsNM3F, that uses task information during the module identification process. DsNM3F extends our previous space-by-time decomposition method (the so-called sNM3F algorithm, which could assess task performance only after having computed modules) to identify modules gauging between two complementary objectives: reconstruction of the original data and reliable discrimination of the performed tasks. We show that DsNM3F recovers the task dependence of module activations more accurately than sNM3F. We also apply it to electromyographic signals recorded during performance of a variety of arm pointing tasks and identify spatial and temporal modules of muscle activity that are highly consistent with previous studies. DsNM3F achieves perfect task categorization without significant loss in data approximation when task information is available and generalizes as well as sNM3F when applied to new data. These findings suggest that the space-by-time decomposition of muscle activity finds robust task-discriminating modular representations of muscle activity and that the insertion of task discrimination objectives is useful for describing the task modulation of module recruitment. PMID:26217213

Task-discriminative space-by-time factorization of muscle activity.

PubMed

Delis, Ioannis; Panzeri, Stefano; Pozzo, Thierry; Berret, Bastien

2015-01-01

Movement generation has been hypothesized to rely on a modular organization of muscle activity. Crucial to this hypothesis is the ability to perform reliably a variety of motor tasks by recruiting a limited set of modules and combining them in a task-dependent manner. Thus far, existing algorithms that extract putative modules of muscle activations, such as Non-negative Matrix Factorization (NMF), identify modular decompositions that maximize the reconstruction of the recorded EMG data. Typically, the functional role of the decompositions, i.e., task accomplishment, is only assessed a posteriori. However, as motor actions are defined in task space, we suggest that motor modules should be computed in task space too. In this study, we propose a new module extraction algorithm, named DsNM3F, that uses task information during the module identification process. DsNM3F extends our previous space-by-time decomposition method (the so-called sNM3F algorithm, which could assess task performance only after having computed modules) to identify modules gauging between two complementary objectives: reconstruction of the original data and reliable discrimination of the performed tasks. We show that DsNM3F recovers the task dependence of module activations more accurately than sNM3F. We also apply it to electromyographic signals recorded during performance of a variety of arm pointing tasks and identify spatial and temporal modules of muscle activity that are highly consistent with previous studies. DsNM3F achieves perfect task categorization without significant loss in data approximation when task information is available and generalizes as well as sNM3F when applied to new data. These findings suggest that the space-by-time decomposition of muscle activity finds robust task-discriminating modular representations of muscle activity and that the insertion of task discrimination objectives is useful for describing the task modulation of module recruitment.

Cognitive tasks promote automatization of postural control in young and older adults.

PubMed

Potvin-Desrochers, Alexandra; Richer, Natalie; Lajoie, Yves

2017-09-01

Researchers looking at the effects of performing a concurrent cognitive task on postural control in young and older adults using traditional center-of-pressure measures and complexity measures found discordant results. Results of experiments showing improvements of stability have suggested the use of strategies such as automatization of postural control or stiffening strategy. This experiment aimed to confirm in healthy young and older adults that performing a cognitive task while standing leads to improvements that are due to automaticity of sway by using sample entropy. Twenty-one young adults and twenty-five older adults were asked to stand on a force platform while performing a cognitive task. There were four cognitive tasks: simple reaction time, go/no-go reaction time, equation and occurrence of a digit in a number sequence. Results demonstrated decreased sway area and variability as well as increased sample entropy for both groups when performing a cognitive task. Results suggest that performing a concurrent cognitive task promotes the adoption of an automatic postural control in young and older adults as evidenced by an increased postural stability and postural sway complexity. Copyright © 2017 Elsevier B.V. All rights reserved.

Self-Reported Stickiness of Mind-Wandering Affects Task Performance

PubMed Central

van Vugt, Marieke K.; Broers, Nico

2016-01-01

When asked to perform a certain task, we typically spend a decent amount of time thinking thoughts unrelated to that task–a phenomenon referred to as “mind-wandering.” It is thought that this mind-wandering is driven at least in part by our unfinished goals and concerns. Previous studies have shown that just after presenting a participant with their own concerns, their reports of task-unrelated thinking increased somewhat. However, effects of these concerns on task performance were somewhat inconsistent. In this study we take the opposite approach, and examine whether task performance depends on the self-reported thought content. Specifically, a particularly intriguing aspect of mind-wandering that has hitherto received little attention is the difficulty of disengaging from it, in other words, the “stickiness” of the thoughts. While presenting participants with their own concerns was not associated with clear effects on task performance, we showed that the reports of off-task thinking and variability of response times increased with the amount of self-reported stickiness of thoughts. This suggests that the stickiness of mind-wandering is a relevant variable, and participants are able to meaningfully report on it. PMID:27242636

Thinking About a Task Is Associated with Increased Connectivity in Regions Activated by Task Performance

PubMed Central

Robertson, Edwin M.; Manoach, Dara S.; Stickgold, Robert

2016-01-01

Abstract We investigated whether functional neuroimaging of quiet “rest” can reveal the neural correlates of conscious thought. Using resting-state functional MRI, we measured functional connectivity during a resting scan that immediately followed performance of a finger tapping motor sequence task. Self-reports of the amount of time spent thinking about the task during the resting scan correlated with connectivity between regions of the motor network activated during task performance. Thus, thinking about a task is associated with coordinated activity in brain regions responsible for that task's performance. More generally, this study demonstrates the feasibility of using the combination of functional connectivity MRI and self-reports to examine the neural correlates of thought. PMID:26650337

Measurement of Temporal Awareness in Air Traffic Control

NASA Technical Reports Server (NTRS)

Rantanen, E.M.

2009-01-01

Temporal awareness, or level 3 situation awareness, is critical to successful control of air traffic, yet the construct remains ill-defined and difficult to measure. This research sought evidence for air traffic controllers awareness of temporal characteristics of their tasks in data from a high-fidelity system evaluation simulation. Five teams of controllers worked on four scenarios with different traffic load. Several temporal parameters were defined for each task controllers performed during a simulation run and their actions on the tasks were timed relative to them. Controllers showed a strong tendency to prioritize tasks according to a first come, first served principle. This trend persisted as task load increased. Also evident was awareness of the urgency of tasks, as tasks with impending closing of a window of opportunity were performed before tasks that had longer time available before closing of the window.

Performance comparison of heuristic algorithms for task scheduling in IaaS cloud computing environment.

PubMed

Madni, Syed Hamid Hussain; Abd Latiff, Muhammad Shafie; Abdullahi, Mohammed; Abdulhamid, Shafi'i Muhammad; Usman, Mohammed Joda

2017-01-01

Cloud computing infrastructure is suitable for meeting computational needs of large task sizes. Optimal scheduling of tasks in cloud computing environment has been proved to be an NP-complete problem, hence the need for the application of heuristic methods. Several heuristic algorithms have been developed and used in addressing this problem, but choosing the appropriate algorithm for solving task assignment problem of a particular nature is difficult since the methods are developed under different assumptions. Therefore, six rule based heuristic algorithms are implemented and used to schedule autonomous tasks in homogeneous and heterogeneous environments with the aim of comparing their performance in terms of cost, degree of imbalance, makespan and throughput. First Come First Serve (FCFS), Minimum Completion Time (MCT), Minimum Execution Time (MET), Max-min, Min-min and Sufferage are the heuristic algorithms considered for the performance comparison and analysis of task scheduling in cloud computing.

Performance comparison of heuristic algorithms for task scheduling in IaaS cloud computing environment

PubMed Central

Madni, Syed Hamid Hussain; Abd Latiff, Muhammad Shafie; Abdullahi, Mohammed; Usman, Mohammed Joda

2017-01-01

Cloud computing infrastructure is suitable for meeting computational needs of large task sizes. Optimal scheduling of tasks in cloud computing environment has been proved to be an NP-complete problem, hence the need for the application of heuristic methods. Several heuristic algorithms have been developed and used in addressing this problem, but choosing the appropriate algorithm for solving task assignment problem of a particular nature is difficult since the methods are developed under different assumptions. Therefore, six rule based heuristic algorithms are implemented and used to schedule autonomous tasks in homogeneous and heterogeneous environments with the aim of comparing their performance in terms of cost, degree of imbalance, makespan and throughput. First Come First Serve (FCFS), Minimum Completion Time (MCT), Minimum Execution Time (MET), Max-min, Min-min and Sufferage are the heuristic algorithms considered for the performance comparison and analysis of task scheduling in cloud computing. PMID:28467505

The effect of single-task and dual-task balance exercise programs on balance performance in adults with osteoporosis: a randomized controlled preliminary trial.

PubMed

Konak, H E; Kibar, S; Ergin, E S

2016-11-01

Osteoporosis is a serious disease characterized by muscle weakness in the lower extremities, shortened length of trunk, and increased dorsal kyphosis leading to poor balance performance. Although balance impairment increases in adults with osteoporosis, falls and fall-related injuries have been shown to occur mainly during the dual-task performance. Several studies have shown that dual-task performance was improved with specific repetitive dual-task exercises. The aims of this study were to compare the effect of single- and dual-task balance exercise programs on static balance, dynamic balance, and activity-specific balance confidence in adults with osteoporosis and to assess the effectiveness of dual-task balance training on gait speed under dual-task conditions. Older adults (N = 42) (age range, 45-88 years) with osteoporosis were randomly assigned into two groups. Single-task balance training group was given single-task balance exercises for 4 weeks, whereas dual-task balance training group received dual-task balance exercises. Participants received 45-min individualized training session, three times a week. Static balance was evaluated by one-leg stance (OLS) and a kinesthetic ability trainer (KAT) device. Dynamic balance was measured by the Berg Balance Scale (BBS), Time Up and Go (TUG) test, and gait speed. Self-confidence was assessed with the Activities-specific Balance Confidence (ABC-6) scale. Assessments were performed at baseline and after the 4-week program. At the end of the treatment periods, KAT score, BBS score, time in OLS and TUG, gait speeds under single- and dual-task conditions, and ABC-6 scale scores improved significantly in all patients (p < 0.05). However, BBS and gait speeds under single- and dual-task conditions showed significantly greater improvement in the dual-task balance training group than in the single-task balance training group (p < 0.05). ABC-6 scale scores improved more in the single-task balance training group than in the dual-task balance training group (p < 0.05). A 4-week single- and dual-task balance exercise programs are effective in improving static balance, dynamic balance, and balance confidence during daily activities in older adults with osteoporosis. However, single- and dual-task gait speeds showed greater improvement following the application of a specific type of dual-task exercise programs. 24102014-2.

Real-time evaluation and visualization of learner performance in a mixed-reality environment for clinical breast examination.

PubMed

Kotranza, Aaron; Lind, D Scott; Lok, Benjamin

2012-07-01

We investigate the efficacy of incorporating real-time feedback of user performance within mixed-reality environments (MREs) for training real-world tasks with tightly coupled cognitive and psychomotor components. This paper presents an approach to providing real-time evaluation and visual feedback of learner performance in an MRE for training clinical breast examination (CBE). In a user study of experienced and novice CBE practitioners (n = 69), novices receiving real-time feedback performed equivalently or better than more experienced practitioners in the completeness and correctness of the exam. A second user study (n = 8) followed novices through repeated practice of CBE in the MRE. Results indicate that skills improvement in the MRE transfers to the real-world task of CBE of human patients. This initial case study demonstrates the efficacy of MREs incorporating real-time feedback for training real-world cognitive-psychomotor tasks.

A free, easy-to-use, computer-based simple and four-choice reaction time programme: the Deary-Liewald reaction time task.

PubMed

Deary, Ian J; Liewald, David; Nissan, Jack

2011-03-01

Reaction time tasks are used widely in basic and applied psychology. There is a need for an easy-to-use, freely available programme that can run simple and choice reaction time tasks with no special software. We report the development of, and make available, the Deary-Liewald reaction time task. It is initially tested here on 150 participants, aged from 18 to 80, alongside another widely used reaction time device and tests of fluid and crystallised intelligence and processing speed. The new task's parameters perform as expected with respect to age and intelligence differences. The new task's parameters are reliable, and have very high correlations with the existing task. We also provide instructions for downloading and using the new reaction time programme, and we encourage other researchers to use it.

Effects of Mother-Infant Social Interactions on Infants' Subsequent Contingency Task Performance.

ERIC Educational Resources Information Center

Dunham, Philip; Dunham, Frances

1990-01-01

Infants participated in a nonsocial contingency task immediately after a social interaction with their mothers. The amount of time mothers and infants spent in a state of vocal turn-taking predicted individual differences in infants' subsequent performance on the contingency task. (PCB)

Sleep Deprivation and Time-Based Prospective Memory.

PubMed

Esposito, Maria José; Occhionero, Miranda; Cicogna, PierCarla

2015-11-01

To evaluate the effect of sleep deprivation on time-based prospective memory performance, that is, realizing delayed intentions at an appropriate time in the future (e.g., to take a medicine in 30 minutes). Between-subjects experimental design. The experimental group underwent 24 h of total sleep deprivation, and the control group had a regular sleep-wake cycle. Participants were tested at 08:00. Laboratory. Fifty healthy young adults (mean age 22 ± 2.1, 31 female). 24 h of total sleep deprivation. Participants were monitored by wrist actigraphy for 3 days before the experimental session. The following cognitive tasks were administered: one time-based prospective memory task and 3 reasoning tasks as ongoing activity. Objective and subjective vigilance was assessed by the psychomotor vigilance task and a visual analog scale, respectively. To measure the time-based prospective memory task we assessed compliance and clock checking behavior (time monitoring). Sleep deprivation negatively affected time-based prospective memory compliance (P < 0.001), objective vigilance (mean RT: P < 0.001; slowest 10% RT: P < 0.001; lapses: P < 0.005), and subjective vigilance (P < 0.0001). Performance on reasoning tasks and time monitoring behavior did not differ between groups. The results highlight the potential dangerous effects of total sleep deprivation on human behavior, particularly the ability to perform an intended action after a few minutes. Sleep deprivation strongly compromises time-based prospective memory compliance but does not affect time check frequency. Sleep deprivation may impair the mechanism that allows the integration of information related to time monitoring with the prospective intention. © 2015 Associated Professional Sleep Societies, LLC.

Multitasking During Degraded Speech Recognition in School-Age Children

PubMed Central

Ward, Kristina M.; Brehm, Laurel

2017-01-01

Multitasking requires individuals to allocate their cognitive resources across different tasks. The purpose of the current study was to assess school-age children’s multitasking abilities during degraded speech recognition. Children (8 to 12 years old) completed a dual-task paradigm including a sentence recognition (primary) task containing speech that was either unprocessed or noise-band vocoded with 8, 6, or 4 spectral channels and a visual monitoring (secondary) task. Children’s accuracy and reaction time on the visual monitoring task was quantified during the dual-task paradigm in each condition of the primary task and compared with single-task performance. Children experienced dual-task costs in the 6- and 4-channel conditions of the primary speech recognition task with decreased accuracy on the visual monitoring task relative to baseline performance. In all conditions, children’s dual-task performance on the visual monitoring task was strongly predicted by their single-task (baseline) performance on the task. Results suggest that children’s proficiency with the secondary task contributes to the magnitude of dual-task costs while multitasking during degraded speech recognition. PMID:28105890

Multitasking During Degraded Speech Recognition in School-Age Children.

PubMed

Grieco-Calub, Tina M; Ward, Kristina M; Brehm, Laurel

2017-01-01

Multitasking requires individuals to allocate their cognitive resources across different tasks. The purpose of the current study was to assess school-age children's multitasking abilities during degraded speech recognition. Children (8 to 12 years old) completed a dual-task paradigm including a sentence recognition (primary) task containing speech that was either unprocessed or noise-band vocoded with 8, 6, or 4 spectral channels and a visual monitoring (secondary) task. Children's accuracy and reaction time on the visual monitoring task was quantified during the dual-task paradigm in each condition of the primary task and compared with single-task performance. Children experienced dual-task costs in the 6- and 4-channel conditions of the primary speech recognition task with decreased accuracy on the visual monitoring task relative to baseline performance. In all conditions, children's dual-task performance on the visual monitoring task was strongly predicted by their single-task (baseline) performance on the task. Results suggest that children's proficiency with the secondary task contributes to the magnitude of dual-task costs while multitasking during degraded speech recognition.

The effects of in-vehicle tasks and time-gap selection while reclaiming control from adaptive cruise control (ACC) with bus simulator.

PubMed

Lin, Tsang-Wei; Hwang, Sheue-Ling; Su, Jau-Ming; Chen, Wan-Hui

2008-05-01

This research aimed to find out the effects of in-vehicle distractions and time-gap settings with a fix-based bus driving simulator in a following scenario. Professional bus drivers were recruited to perform in-vehicle tasks while driving with adaptive cruise control (ACC) of changeable time-gap settings in freeway traffic. Thirty subjects were divided equally into three groups for different in-vehicle task modes (between subjects), including no task distraction, hands-free, and manual modes. Further, time-gap settings for the experimental ACC were: shorter than 1.0 s, 1.0-1.5 s, 1.5-2.0 s, and longer than 2.0 s (within subjects). Longitudinal (mean headway, forward collision rate, and response time) and lateral control (mean lateral lane position and its standard deviation) performance was assessed. In the results, longitudinal control performance was worsened by both shorter time-gaps and heavier in-vehicle tasks. But the interaction indicated that the harm by heavier in-vehicle distraction could be improved by longer time-gaps. As for the lateral control, it would only be negatively affected by shorter time-gap settings. This research indicates the effects of time-gaps and in-vehicle distraction, as well as the interaction. Proper time-gap selection under different in-vehicle distractions can help avoid accidents and keep safe.

Designing for Temporal Awareness: The Role of Temporality in Time-Critical Medical Teamwork

PubMed Central

Kusunoki, Diana S.; Sarcevic, Aleksandra

2016-01-01

This paper describes the role of temporal information in emergency medical teamwork and how time-based features can be designed to support the temporal awareness of clinicians in this fast-paced and dynamic environment. Engagement in iterative design activities with clinicians over the course of two years revealed a strong need for time-based features and mechanisms, including timestamps for tasks based on absolute time and automatic stopclocks measuring time by counting up since task performance. We describe in detail the aspects of temporal awareness central to clinicians’ awareness needs and then provide examples of how we addressed these needs through the design of a shared information display. As an outcome of this process, we define four types of time representation techniques to facilitate the design of time-based features: (1) timestamps based on absolute time, (2) timestamps relative to the process start time, (3) time since task performance, and (4) time until the next required task. PMID:27478880

One Night of Sleep Deprivation Affects Reaction Time, but Not Interference or Facilitation in a Stroop Task

ERIC Educational Resources Information Center

Cain, Sean W.; Silva, Edward J.; Chang, Anne-Marie; Ronda, Joseph M.; Duffy, Jeanne F.

2011-01-01

The Stroop color-naming task is one of the most widely studied tasks involving the inhibition of a prepotent response, regarded as an executive function. Several studies have examined performance on versions of the Stroop task under conditions of acute sleep deprivation. Though these studies revealed effects on Stroop performance, the results…

Gait assessment in mild cognitive impairment and Alzheimer's disease: the effect of dual-task challenges across the cognitive spectrum.

PubMed

Muir, Susan W; Speechley, Mark; Wells, Jennie; Borrie, Michael; Gopaul, Karen; Montero-Odasso, Manuel

2012-01-01

Gait impairment is a prominent falls risk factor and a prevalent feature among older adults with cognitive impairment. However, there is a lack of comparative studies on gait performance and fall risk covering the continuum from normal cognition through mild cognitive impairment (MCI) to Alzheimer's disease (AD). We evaluated gait performance and the response to dual-task challenges in older adults with AD, MCI and normal cognition without a history of falls. We hypothesized that, in older people without history of falls, gait performance will deteriorate across the cognitive spectrum with changes being more evident under dual-tasking. Gait was assessed using an electronic walkway under single and three dual-tasks conditions. Gait velocity and stride time variability were not significantly different between the three groups under the single-task condition. By contrast, significant differences of decreasing velocity (p<0.0001), increasing stride time (p=0.0057) and increasing stride time variability (p=0.0037) were found under dual-task testing for people with MCI and AD. Less automatic and more complex dual-task tests, such as naming animals and serial subtraction by sevens from 100, created the greatest deterioration of gait performance. Gait changes under dual-tasking for the MCI and AD groups were statistically different from the cognitively normal controls. Dual-task assessment exposed gait impairments not obvious under a single-task test condition and may facilitate falls risk identification in cognitively impaired persons without a history of falls. Copyright © 2011 Elsevier B.V. All rights reserved.

Segmenting the Stream of Consciousness: The Psychological Correlates of Temporal Structures in the Time Series Data of a Continuous Performance Task

ERIC Educational Resources Information Center

Smallwood, Jonathan; McSpadden, Merrill; Luus, Bryan; Schooler, Joanthan

2008-01-01

Using principal component analysis, we examined whether structural properties in the time series of response time would identify different mental states during a continuous performance task. We examined whether it was possible to identify regular patterns which were present in blocks classified as lacking controlled processing, either…

Task experience and children’s working memory performance: A perspective from recall timing

PubMed Central

Towse, John N.; Cowan, Nelson; Horton, Neil J.; Whytock, Shealagh

2008-01-01

Working memory is an important theoretical construct among children, and measures of its capacity predict a range of cognitive skills and abilities. Data from 9-and 11-year-old children illustrate how a chronometric analysis of recall can complement and elaborate recall accuracy in advancing our understanding of working memory. A reading span task was completed by 130 children, 75 of whom were tested on two occasions, with sequence length either increasing or decreasing during test administration. Substantial pauses occur during participants’ recall sequences and they represent consistent performance traits over time, whilst also varying with recall circumstances and task history. Recall pauses help to predict reading and number skills, alongside as well as separate from levels of recall accuracy. The task demands of working memory change as a function of task experience, with a combination of accuracy and response timing in novel task situations being the strongest predictor of cognitive attainment. PMID:18473637

Time Sharing Between Robotics and Process Control: Validating a Model of Attention Switching.

PubMed

Wickens, Christopher Dow; Gutzwiller, Robert S; Vieane, Alex; Clegg, Benjamin A; Sebok, Angelia; Janes, Jess

2016-03-01

The aim of this study was to validate the strategic task overload management (STOM) model that predicts task switching when concurrence is impossible. The STOM model predicts that in overload, tasks will be switched to, to the extent that they are attractive on task attributes of high priority, interest, and salience and low difficulty. But more-difficult tasks are less likely to be switched away from once they are being performed. In Experiment 1, participants performed four tasks of the Multi-Attribute Task Battery and provided task-switching data to inform the role of difficulty and priority. In Experiment 2, participants concurrently performed an environmental control task and a robotic arm simulation. Workload was varied by automation of arm movement and both the phases of environmental control and existence of decision support for fault management. Attention to the two tasks was measured using a head tracker. Experiment 1 revealed the lack of influence of task priority and confirmed the differing roles of task difficulty. In Experiment 2, the percentage attention allocation across the eight conditions was predicted by the STOM model when participants rated the four attributes. Model predictions were compared against empirical data and accounted for over 95% of variance in task allocation. More-difficult tasks were performed longer than easier tasks. Task priority does not influence allocation. The multiattribute decision model provided a good fit to the data. The STOM model is useful for predicting cognitive tunneling given that human-in-the-loop simulation is time-consuming and expensive. © 2016, Human Factors and Ergonomics Society.

Transferability of Virtual Reality, Simulation-Based, Robotic Suturing Skills to a Live Porcine Model in Novice Surgeons: A Single-Blind Randomized Controlled Trial.

PubMed

Vargas, Maria V; Moawad, Gaby; Denny, Kathryn; Happ, Lindsey; Misa, Nana Yaa; Margulies, Samantha; Opoku-Anane, Jessica; Abi Khalil, Elias; Marfori, Cherie

To assess whether a robotic simulation curriculum for novice surgeons can improve performance of a suturing task in a live porcine model. Randomized controlled trial (Canadian Task Force classification I). Academic medical center. Thirty-five medical students without robotic surgical experience. Participants were enrolled in an online session of training modules followed by an in-person orientation. Baseline performance testing on the Mimic Technologies da Vinci Surgical Simulator (dVSS) was also performed. Participants were then randomly assigned to the completion of 4 dVSS training tasks (camera clutching 1, suture sponge 1 and 2, and tubes) versus no further training. The intervention group performed each dVSS task until proficiency or up to 10 times. A final suturing task was performed on a live porcine model, which was video recorded and blindly assessed by experienced surgeons. The primary outcomes were Global Evaluative Assessment of Robotic Skills (GEARS) scores and task time. The study had 90% power to detect a mean difference of 3 points on the GEARS scale, assuming a standard deviation (SD) of 2.65, and 80% power to detect a mean difference of 3 minutes, assuming an SD of 3 minutes. There were no differences in demographics and baseline skills between the 2 groups. No significant differences in task time in minutes or GEARS scores were seen for the final suturing task between the intervention and control groups, respectively (9.2 [2.65] vs 9.9 [2.07] minutes, p = .406; and 15.37 [2.51] vs 15.25 [3.38], p = .603). The 95% confidence interval for the difference in mean task times was -2.36 to .96 minutes and for mean GEARS scores -1.91 to 2.15 points. Live suturing task performance was not improved with a proficiency-based virtual reality simulation suturing curriculum compared with standard orientation to the da Vinci robotic console in a group of novice surgeons. Published by Elsevier Inc.

The impact of reward and punishment on skill learning depends on task demands

PubMed Central

Steel, Adam; Silson, Edward H.; Stagg, Charlotte J.; Baker, Chris I.

2016-01-01

Reward and punishment motivate behavior, but it is unclear exactly how they impact skill performance and whether the effect varies across skills. The present study investigated the effect of reward and punishment in both a sequencing skill and a motor skill context. Participants trained on either a sequencing skill (serial reaction time task) or a motor skill (force-tracking task). Skill knowledge was tested immediately after training, and again 1 hour, 24–48 hours, and 30 days after training. We found a dissociation of the effects of reward and punishment on the tasks, primarily reflecting the impact of punishment. While punishment improved serial reaction time task performance, it impaired force-tracking task performance. In contrast to prior literature, neither reward nor punishment benefitted memory retention, arguing against the common assumption that reward ubiquitously benefits skill retention. Collectively, these results suggest that punishment impacts skilled behavior more than reward in a complex, task dependent fashion. PMID:27786302

The impact of reward and punishment on skill learning depends on task demands.

PubMed

Steel, Adam; Silson, Edward H; Stagg, Charlotte J; Baker, Chris I

2016-10-27

Reward and punishment motivate behavior, but it is unclear exactly how they impact skill performance and whether the effect varies across skills. The present study investigated the effect of reward and punishment in both a sequencing skill and a motor skill context. Participants trained on either a sequencing skill (serial reaction time task) or a motor skill (force-tracking task). Skill knowledge was tested immediately after training, and again 1 hour, 24-48 hours, and 30 days after training. We found a dissociation of the effects of reward and punishment on the tasks, primarily reflecting the impact of punishment. While punishment improved serial reaction time task performance, it impaired force-tracking task performance. In contrast to prior literature, neither reward nor punishment benefitted memory retention, arguing against the common assumption that reward ubiquitously benefits skill retention. Collectively, these results suggest that punishment impacts skilled behavior more than reward in a complex, task dependent fashion.

Temporal profile of prolonged, night-time driving performance: breaks from driving temporarily reduce time-on-task fatigue but not sleepiness.

PubMed

Phipps-Nelson, Jo; Redman, Jennifer R; Rajaratnam, Shantha M W

2011-09-01

Breaks are often used by drivers to counteract sleepiness and time-on-task fatigue during prolonged driving. We examined the temporal profile of changes in driving performance, electroencephalogram (EEG) activity and subjective measures of sleepiness and fatigue during prolonged nocturnal driving in a car simulator. In addition, the study examined the impact of regular breaks from driving on performance, sleepiness and fatigue. Healthy volunteers (n=12, 23-45 years) maintained a regular sleep-wake pattern for 14 days and were then in a laboratory from 21:00 to 08:30 hours. The driving simulator scene was designed to simulate monotonous night-time rural driving. Participants drove 4 × 2-h test sessions, with a break from driving of 1 h between each session. During the break participants performed tests assessing sleepiness and fatigue, and psychomotor performance (~30 mins), and then were permitted to sit quietly. They were monitored for wakefulness, and not permitted to nap or ingest caffeine. EEG was recorded during the driving task, and subjective assessments of sleepiness and fatigue were obtained at the start and completion of each session. We found that driving performance deteriorated (2.5-fold), EEG delta, theta and alpha activity increased, and subjective sleepiness and fatigue ratings increased across the testing period. Driving performance and fatigue ratings improved following the scheduled breaks from driving, while the breaks did not affect EEG activity and subjective sleepiness. Time-on-task effects increased through the testing period, indicating that these effects are exacerbated by increasing sleepiness. Breaks from driving without sleep temporarily ameliorate time-on-task fatigue, but provide little benefit to the sleepy driver. © 2010 European Sleep Research Society.

An Occupational Performance Test Validation Program for Fire Fighters at the Kennedy Space Center

NASA Technical Reports Server (NTRS)

Schonfeld, Brian R.; Doerr, Donald F.; Convertino, Victor A.

1990-01-01

We evaluated performance of a modified Combat Task Test (CTT) and of standard fitness tests in 20 male subjects to assess the prediction of occupational performance standards for Kennedy Space Center fire fighters. The CTT consisted of stair-climbing, a chopping simulation, and a victim rescue simulation. Average CTT performance time was 3.61 +/- 0.25 min (SEM) and all CTT tasks required 93% to 97% maximal heart rate. By using scores from the standard fitness tests, a multiple linear regression model was fitted to each parameter: the stairclimb (r(exp 2) = .905, P less than .05), the chopping performance time (r(exp 2) = .582, P less than .05), the victim rescue time (r(exp 2) = .218, P = not significant), and the total performance time (r(exp 2) = .769, P less than .05). Treadmill time was the predominant variable, being the major predictor in two of four models. These results indicated that standardized fitness tests can predict performance on some CTT tasks and that test predictors were amenable to exercise training.

Teaching high-performance skills using above-real-time training

NASA Technical Reports Server (NTRS)

Guckenberger, Dutch; Uliano, Kevin C.; Lane, Norman E.

1993-01-01

The above real-time training (ARTT) concept is an approach to teaching high-performance skills. ARTT refers to a training paradigm that places the operator in a simulated environment that functions at faster than normal time. It represents a departure from the intuitive, but not often supported, feeling that the best practice is determined by the training environment with the highest fidelity. This approach is hypothesized to provide greater 'transfer value' per simulation trial, by incorporating training techniques and instructional features into the simulator. Two related experiments are discussed. In the first, 25 naive male subjects performed three tank gunnery tasks on a simulator under varying levels of time acceleration (i.e., 1.0x, 1.6x, 2.0x, sequential, and mixed). They were then transferred to a standard (1.0x) condition for testing. Every accelerated condition or combination of conditions produced better training and transfer than the standard condition. Most effective was the presentation of trials at 1.0x, 1.6x, and 2.0x in a random order during training. Overall, the best ARTT group scored about 50 percent higher and trained in 25 percent less time compared to the real-time control group. In the second experiment, 24 mission-capable F-16 pilots performed three tasks on a part-task F-16A flight simulator under varying levels of time compression (i.e., 1.0x, 1.5x, 2.0x, and random). All subjects were then tested in a real-time environment. The emergency procedure (EP) task results showed increased accuracy for the ARTT groups. In testing (transfer), the ARTT groups not only performed the EP more accurately, but dealt with a simultaneous enemy significantly better than a real-time control group. Although the findings on an air combat maneuvering task and stern conversion task were mixed, most measures indicated that the ARTT groups performed better and faster than a real-time control group. Other implications for ARTT are discussed along with future research directions.

Two Trackers Are Better than One: Information about the Co-actor's Actions and Performance Scores Contribute to the Collective Benefit in a Joint Visuospatial Task.

PubMed

Wahn, Basil; Kingstone, Alan; König, Peter

2017-01-01

When humans collaborate, they often distribute task demands in order to reach a higher performance compared to performing the same task alone (i.e., a collective benefit). Here, we tested to what extent receiving information about the actions of a co-actor, performance scores, or receiving both types of information impacts the collective benefit in a collaborative multiple object tracking task. In a between-subject design, pairs of individuals jointly tracked a subset of target objects among several moving distractor objects on a computer screen for a 100 trials. At the end of a trial, pairs received performance scores (Experiment 1), information about their partner's target selections (Experiment 2), or both types of information (Experiment 3). In all experiments, the performance of the pair exceeded the individual performances and the simulated performance of two independent individuals combined. Initially, when receiving both types of information (Experiment 3), pairs achieved the highest performance and divided task demands most efficiently compared to the other two experiments. Over time, performances and the ability to divide task demands for pairs receiving a single type of information converged with those receiving both, suggesting that pairs' coordination strategies become equally effective over time across experiments. However, pairs' performances never reached a theoretical limit of performance in all experiments. For distributing task demands, members of a pair predominantly used a left-right division of labor strategy (i.e., the leftmost targets were tracked by one co-actor while the rightmost targets were tracked by the other co-actor). Overall, findings of the present study suggest that receiving information about actions of a co-actor, performance scores, or receiving both enables pairs to devise effective division of labor strategies in a collaborative visuospatial task. However, when pairs had both types of information available, the formation of division of labor strategies was facilitated, indicating that pairs benefited the most from having both types of information available (i.e., actions about the co-actor and performance scores). Findings are applicable to circumstances in which humans need to perform collaborative visuospatial tasks that are time-critical and/or only allow a very limited exchange of information between co-actors.

Long-Term Effects of Attentional Performance on Functional Brain Network Topology

PubMed Central

Breckel, Thomas P. K.; Thiel, Christiane M.; Bullmore, Edward T.; Zalesky, Andrew; Patel, Ameera X.; Giessing, Carsten

2013-01-01

Individuals differ in their cognitive resilience. Less resilient people demonstrate a greater tendency to vigilance decrements within sustained attention tasks. We hypothesized that a period of sustained attention is followed by prolonged changes in the organization of “resting state” brain networks and that individual differences in cognitive resilience are related to differences in post-task network reorganization. We compared the topological and spatial properties of brain networks as derived from functional MRI data (N = 20) recorded for 6 mins before and 12 mins after the performance of an attentional task. Furthermore we analysed changes in brain topology during task performance and during the switches between rest and task conditions. The cognitive resilience of each individual was quantified as the rate of increase in response latencies over the 32-minute time course of the attentional paradigm. On average, functional networks measured immediately post-task demonstrated significant and prolonged changes in network organization compared to pre-task networks with higher connectivity strength, more clustering, less efficiency, and shorter distance connections. Individual differences in cognitive resilience were significantly correlated with differences in the degree of recovery of some network parameters. Changes in network measures were still present in less resilient individuals in the second half of the post-task period (i.e. 6–12 mins after task completion), while resilient individuals already demonstrated significant reductions of functional connectivity and clustering towards pre-task levels. During task performance brain topology became more integrated with less clustering and higher global efficiency, but linearly decreased with ongoing time-on-task. We conclude that sustained attentional task performance has prolonged, “hang-over” effects on the organization of post-task resting-state brain networks; and that more cognitively resilient individuals demonstrate faster rates of network recovery following a period of attentional effort. PMID:24040185

Time and interference: Effects on working memory.

PubMed

Botto, Marta; Palladino, Paola

2016-05-01

This study tested predictions from the time-based resource-sharing (TBRS) model with a classical verbal working memory (WM) task, where target and non-target information interfere strongly with each other. Different predictions can be formulated according to the dominant perspectives (TBRS and interference hypothesis) on the role of inhibitory control in WM task performance. Here, we aimed to trace the activation of irrelevant information, examining priming effects in a lexical decision task immediately following WM recall. Results indicate the roles of both time and interference constraints in determining task performance. In particular, the role of time available seemed crucial at the highest WM loads (i.e., 3 and 4 memoranda). These were also associated with a higher activation of no-longer-relevant information but, in this case, independently from time available for processing. © 2015 The British Psychological Society.

Driving performance in persons with mild to moderate symptoms of multiple sclerosis.

PubMed

Devos, Hannes; Brijs, Tom; Alders, Geert; Wets, Geert; Feys, Peter

2013-08-01

To investigate whether driving performance is impaired in persons with mild to moderate multiple sclerosis (MS). This study included 15 persons with MS (pwMS) and 17 healthy controls. The MS group exhibited mild to moderate impairments on the Expanded Disability Status Scale (median, Q1-Q3; 3.5, 2.5-4). The driving simulation required participants to drive in daily traffic while attending to a divided attention (DA) task. Computerized measures on the driving task included number of accidents, tickets, speed maintenance, standard deviation of lateral position, and time to collision. Response times and accuracy on the DA task were also computer generated. Additionally, pwMS completed a clinical evaluation encompassing motor, functional, visual, psychosocial and cognitive tests. No differences between healthy controls and pwMS were observed on all measures of the primary driving task. PwMS performed worse than healthy controls on DA response time (3.10 s, 2.87-3.68 versus 2.15 s, 2.04-2.43; p = 0.001) and accuracy (15 correct answers, 11-18 versus 24 correct answers, 22-25; p < 0.0001). Depression was significantly associated with time to collision (r = -0.77; p < 0.01). Subjects with mild to moderate MS are able to prioritize the driving task above the DA task. The relationship between depression and driving performance in MS merits further investigation.

Comparison of nitrile gloves and nitrile over Nomex gloves.

PubMed

Vorih, Deirdre Cronin; Bolton, Lauri D; Marcelynas, James; Nowicki, Thomas A; Jacobs, Lenworth; Robinson, Kenneth J

2009-01-01

Aeromedical flight crews must perform many tasks in flight requiring manual dexterity and fine precision. A common perception is that safety-enhancing fire-retardant gloves compromise patient care if worn during such tasks by providing added bulk and barrier to the hand. This study is a quantitative and qualitative analysis of this possible compromise to patient care. Sixteen practicing flight nurses and respiratory therapists were asked to perform 10 different standard patient care tasks while wearing either nitrile gloves or a nitrile-Nomex glove pair. Tasks were timed, rated as completed successfully or not, and were subsequently judged subjectively by the participants. Whereas the time required to insert an intravenous catheter and to insert a central line while wearing only nitrile gloves was significantly faster than when wearing both gloves, the time to perform all other tasks was not significantly different. In subjective ratings, the nitrile glove alone was scored significantly better than the two-glove combination by the study participants. Comfort, dexterity, tactile discrimination, and ease of use were all adversely affected by wearing a Nomex glove under a nitrile glove. Although the differences in times for most tasks may not be clinically significant, the difference in the subjective parameters may be great enough to cause helicopter emergency medical services (HEMS) practitioners to not wear Nomex gloves under nitrile gloves while performing procedures.

Application of auditory signals to the operation of an agricultural vehicle: results of pilot testing.

PubMed

Karimi, D; Mondor, T A; Mann, D D

2008-01-01

The operation of agricultural vehicles is a multitask activity that requires proper distribution of attentional resources. Human factors theories suggest that proper utilization of the operator's sensory capacities under such conditions can improve the operator's performance and reduce the operator's workload. Using a tractor driving simulator, this study investigated whether auditory cues can be used to improve performance of the operator of an agricultural vehicle. Steering of a vehicle was simulated in visual mode (where driving error was shown to the subject using a lightbar) and in auditory mode (where a pair of speakers were used to convey the driving error direction and/or magnitude). A secondary task was also introduced in order to simulate the monitoring of an attached machine. This task included monitoring of two identical displays, which were placed behind the simulator, and responding to them, when needed, using a joystick. This task was also implemented in auditory mode (in which a beep signaled the subject to push the proper button when a response was needed) and in visual mode (in which there was no beep and visual, monitoring of the displays was necessary). Two levels of difficulty of the monitoring task were used. Deviation of the simulated vehicle from a desired straight line was used as the measure of performance in the steering task, and reaction time to the displays was used as the measure of performance in the monitoring task. Results of the experiments showed that steering performance was significantly better when steering was a visual task (driving errors were 40% to 60% of the driving errors in auditory mode), although subjective evaluations showed that auditory steering could be easier, depending on the implementation. Performance in the monitoring task was significantly better for auditory implementation (reaction time was approximately 6 times shorter), and this result was strongly supported by subjective ratings. The majority of the subjects preferred the combination of visual mode for the steering task and auditory mode for the monitoring task.

Longitudinal development of prefrontal function during early childhood.

PubMed

Moriguchi, Yusuke; Hiraki, Kazuo

2011-04-01

This is a longitudinal study on development of prefrontal function in young children. Prefrontal areas have been observed to develop dramatically during early childhood. To elucidate this development, we gave children cognitive shifting tasks related to prefrontal function at 3 years of age (Time 1) and 4 years of age (Time 2). We then monitored developmental changes in behavioral performance and examined prefrontal activation using near infrared spectroscopy. We found that children showed better behavioral performance and significantly stronger inferior prefrontal activation at Time 2 than they did at Time 1. Moreover, we demonstrated individual differences in prefrontal activation for the same behavioral tasks. Children who performed better in tasks at Time 1 showed significant activation of the right inferior prefrontal regions at Time 1 and significant activation of the bilateral inferior prefrontal regions at Time 2. Children who showed poorer performance at Time 1 exhibited no significant inferior prefrontal activation at Time 1 but significant left inferior prefrontal activation at Time 2. These results indicate the importance of the longitudinal method to address the link between cognitive and neural development. Copyright © 2011 Elsevier Ltd. All rights reserved.

Ego Depletion in Real-Time: An Examination of the Sequential-Task Paradigm.

PubMed

Arber, Madeleine M; Ireland, Michael J; Feger, Roy; Marrington, Jessica; Tehan, Joshua; Tehan, Gerald

2017-01-01

Current research into self-control that is based on the sequential task methodology is currently at an impasse. The sequential task methodology involves completing a task that is designed to tax self-control resources which in turn has carry-over effects on a second, unrelated task. The current impasse is in large part due to the lack of empirical research that tests explicit assumptions regarding the initial task. Five studies test one key, untested assumption underpinning strength (finite resource) models of self-regulation: Performance will decline over time on a task that depletes self-regulatory resources. In the aftermath of high profile replication failures using a popular letter-crossing task and subsequent criticisms of that task, the current studies examined whether depletion effects would occur in real time using letter-crossing tasks that did not invoke habit-forming and breaking, and whether these effects were moderated by administration type (paper and pencil vs. computer administration). Sample makeup and sizes as well as response formats were also varied across the studies. The five studies yielded a clear and consistent pattern of increasing performance deficits (errors) as a function of time spent on task with generally large effects and in the fifth study the strength of negative transfer effects to a working memory task were related to individual differences in depletion. These results demonstrate that some form of depletion is occurring on letter-crossing tasks though whether an internal regulatory resource reservoir or some other factor is changing across time remains an important question for future research.

Ego Depletion in Real-Time: An Examination of the Sequential-Task Paradigm

PubMed Central

Arber, Madeleine M.; Ireland, Michael J.; Feger, Roy; Marrington, Jessica; Tehan, Joshua; Tehan, Gerald

2017-01-01

Current research into self-control that is based on the sequential task methodology is currently at an impasse. The sequential task methodology involves completing a task that is designed to tax self-control resources which in turn has carry-over effects on a second, unrelated task. The current impasse is in large part due to the lack of empirical research that tests explicit assumptions regarding the initial task. Five studies test one key, untested assumption underpinning strength (finite resource) models of self-regulation: Performance will decline over time on a task that depletes self-regulatory resources. In the aftermath of high profile replication failures using a popular letter-crossing task and subsequent criticisms of that task, the current studies examined whether depletion effects would occur in real time using letter-crossing tasks that did not invoke habit-forming and breaking, and whether these effects were moderated by administration type (paper and pencil vs. computer administration). Sample makeup and sizes as well as response formats were also varied across the studies. The five studies yielded a clear and consistent pattern of increasing performance deficits (errors) as a function of time spent on task with generally large effects and in the fifth study the strength of negative transfer effects to a working memory task were related to individual differences in depletion. These results demonstrate that some form of depletion is occurring on letter-crossing tasks though whether an internal regulatory resource reservoir or some other factor is changing across time remains an important question for future research. PMID:29018390

Operator strategies under varying conditions of workload

NASA Technical Reports Server (NTRS)

Arnegard, Ruth J.

1991-01-01

An attempt was made to operationally define and measure strategic behavior in a complex multiple task environment. The Multi-Attribute Task battery was developed to simulate various aspects of flight and consisted of an auditory communication task, monitoring tasks, a tracking tasks, a resource management task which allowed a wide range of responding patterns, and a scheduling window which allowed operators to predict changes in workload. This battery was validated for its sensitivity to strategic behavior, and baseline measures for each individual task were collected. Twenty-four undergraduate and graduate students then performed the battery for four 64 minute sessions which took place over a period of 2 days. Each subject performed the task battery under four levels of workload, which were presented for equal lengths of time during all four sessions. Results indicated that in general, performance improves as a function of experience with the battery, but that performance decreased as workload level increased. The data also showed that subjects developed strategies for responding to the resource management task which allowed them to manage the high workload levels more efficiently. This particular strategy developed over time but was also associated with errors of complacency. These results are presented along with implications for the aviation field and areas of future research.

An initial test of a normative Figure Of Merit for the quality of overall task performance

NASA Technical Reports Server (NTRS)

Lemay, Moira; Comstock, J. R., Jr.

1990-01-01

An overall indicator, or Figure Of Merit (FOM), of the quality of crew/vehicle system performance is needed to establish the effect of workload on efficiency and to identify overload conditions. A normative FOM is proposed in which performance is measured on a representative task and a normative data base obtained. FOMs for subsequent executions of the task are then reported in terms of weighted deviations from average task performance. Performance of discrete tasks is measured primarily in terms of subtask time and errors. Discrete task performance is then combined with a measure of continuous vehicle control. In order to test the normative FOM procedure, the technique was applied to an existing set of data from a simulated landing task in which standard communications with ATC was compared with a data link communications system. The results indicated that while mean task performance was not affected, task variability, as measured by the FOM, was significantly higher when data link communications were used. In order to establish the sensitivity of the normative FOM method, further testing of the measure is recommended.

Interference between a fast-paced spatial puzzle task and verbal memory demands.

PubMed

Epling, Samantha L; Blakely, Megan J; Russell, Paul N; Helton, William S

2017-06-01

Research continues to provide evidence that people are poor multi-taskers. Cognitive resource theory is a common explanation for the inability to efficiently perform multiple tasks at the same time. This theory proposes that one's limited supply of cognitive resources can be utilized faster than it is replenished, which results in a performance decline, particularly when these limited resources must be allocated among multiple tasks. Researchers have proposed both domain-specific, for example, spatial versus verbal processing resources, and domain general cognitive resources. In the present research, we investigated whether a spatial puzzle task performed simultaneously with a verbal recall task would impair performance in either task or both tasks, compared to performance on the tasks individually. As hypothesized, a reduction in word recall was found when dual-tasking, though performance on the puzzle task did not significantly differ between the single- and dual-task conditions. This is consistent, in part, with both a general resource theory and a Multiple Resource Theory, but further work is required to better understand the cognitive processing system. The employment of the recall task in the dual-task paradigm with a variety of secondary tasks will help to continue mapping out the specificity (or lack thereof) of cognitive resources utilized in various mental and physical tasks.

The effects of Above Real-Time Training (ARTT) in an F-16 simulator

NASA Technical Reports Server (NTRS)

Guckenberger, Dutch; Stanney, Kay; Lane, Norman E.

1994-01-01

In this application of above real-time training (ARTT), 24 mission-capable F-16 pilots performed three tasks on a part-task F-16A flight simulator under varying levels of time compression (i.e., 1.0x, 1.5x, 2.0x, and random). All subjects were then tested in a real-time (1.0x) environment. The three tasks under study were an emergency procedure (EP) task, a one versus two air combat maneuvering (ACM) task, and a stern conversion or air intercept task. All ARTT pilots performed the EP task with 28 percent greater accuracy and were better at dealing with a simultaneous MIG threat, reflected by a six-fold increase in the number of MIG kills compared to a real-time control group. In the stern conversion task, there were no statistical differences between groups. In the ACM task, those pilots trained in the mixed time accelerations were faster to acquire lock and were faster to kill both MIG threats than the other groups. These findings are generally consistent with previous findings that show positive effects of task variations (including time variations) during training. Also discussed are related research findings that support the benefits of ARTT and ARTT's impact on emergency procedure training. Further, a synthesis of multidiscipline research outlining the underlying theoretical basis for ARTT is presented. A proposed model of ARTT based on an analogy to Einstein's theory of special relativity is suggested. Conclusions and an outline of future research directions are presented. Successful current commercialization efforts are related as well as future efforts.

Effects of reward and punishment on task performance, mood and autonomic nervous function, and the interaction with personality.

PubMed

Sakuragi, Sokichi; Sugiyama, Yoshiki

2009-06-01

The effects of reward and punishment are different, and there are individual differences in sensitivity to reward and punishment. The purpose of this study was to investigate the effects of reward and punishment on task performance, mood, and autonomic nervous function, along with the interaction with personality. Twenty-one healthy female subjects volunteered for the experiment. The task performance was evaluated by required time and total errors while performing a Wisconsin Card Sorting Test. We assessed their personalities using the Minnesota Multiphasic Personality Inventory (MMPI) questionnaire, and mood states by a profile of mood states. Autonomic nervous function was estimated by a spectral analysis of heart rate variability, baroreflex sensitivity, and blood pressure. Repeated measures analysis of variance (ANOVA) revealed significant interaction of condition x time course on mood and autonomic nervous activity, which would indicate a less stressed state under the rewarding condition, but revealed no significant interaction of condition x time course on the task performance. The interactions with personality were further analyzed by repeated measures ANOVA applying the clinical scales of MMPI as independent variables, and significant interactions of condition x time course x Pt (psychasthenia) on task performance, mood, and blood pressure, were revealed. That is, the high Pt group, whose members tend to be sensitive and prone to worry, showed gradual improvement of task performance under the punishing situation with slight increase in systolic blood pressure, while showed no improvement under the rewarding situation with fatigue sense attenuation. In contrast, the low Pt group, whose members tend to be adaptive and self-confident, showed gradual improvement under the rewarding situation. Therefore, we should carefully choose the strategy of reward or punishment, considering the interaction with personality as well as the context in which it is given.

The role of musical training in emergent and event-based timing.

PubMed

Baer, L H; Thibodeau, J L N; Gralnick, T M; Li, K Z H; Penhune, V B

2013-01-01

Musical performance is thought to rely predominantly on event-based timing involving a clock-like neural process and an explicit internal representation of the time interval. Some aspects of musical performance may rely on emergent timing, which is established through the optimization of movement kinematics, and can be maintained without reference to any explicit representation of the time interval. We predicted that musical training would have its largest effect on event-based timing, supporting the dissociability of these timing processes and the dominance of event-based timing in musical performance. We compared 22 musicians and 17 non-musicians on the prototypical event-based timing task of finger tapping and on the typically emergently timed task of circle drawing. For each task, participants first responded in synchrony with a metronome (Paced) and then responded at the same rate without the metronome (Unpaced). Analyses of the Unpaced phase revealed that non-musicians were more variable in their inter-response intervals for finger tapping compared to circle drawing. Musicians did not differ between the two tasks. Between groups, non-musicians were more variable than musicians for tapping but not for drawing. We were able to show that the differences were due to less timer variability in musicians on the tapping task. Correlational analyses of movement jerk and inter-response interval variability revealed a negative association for tapping and a positive association for drawing in non-musicians only. These results suggest that musical training affects temporal variability in tapping but not drawing. Additionally, musicians and non-musicians may be employing different movement strategies to maintain accurate timing in the two tasks. These findings add to our understanding of how musical training affects timing and support the dissociability of event-based and emergent timing modes.

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.

A rate-controlled teleoperator task with simulated transport delays

NASA Technical Reports Server (NTRS)

Pennington, J. E.

1983-01-01

A teleoperator-system simulation was used to examine the effects of two control modes (joint-by-joint and resolved-rate), a proximity-display method, and time delays (up to 2 sec) on the control of a five-degree-of-freedom manipulator performing a probe-in-hole alignment task. Four subjects used proportional rotational control and discrete (on-off) translation control with computer-generated visual displays. The proximity display enabled subjects to separate rotational errors from displacement (translation) errors; thus, when the proximity display was used with resolved-rate control, the simulated task was trivial. The time required to perform the simulated task increased linearly with time delay, but time delays had no effect on alignment accuracy. Based on the results of this simulation, several future studies are recommended.

Study to design and develop remote manipulator system

NASA Technical Reports Server (NTRS)

Hill, J. W.; Sword, A. J.

1973-01-01

Human performance measurement techniques for remote manipulation tasks and remote sensing techniques for manipulators are described for common manipulation tasks, performance is monitored by means of an on-line computer capable of measuring the joint angles of both master and slave arms as a function of time. The computer programs allow measurements of the operator's strategy and physical quantities such as task time and power consumed. The results are printed out after a test run to compare different experimental conditions. For tracking tasks, we describe a method of displaying errors in three dimensions and measuring the end-effector position in three dimensions.

Psychometric Functions of Dual-Task Paradigms for Measuring Listening Effort.

PubMed

Wu, Yu-Hsiang; Stangl, Elizabeth; Zhang, Xuyang; Perkins, Joanna; Eilers, Emily

The purpose of the study was to characterize the psychometric functions that describe task performance in dual-task listening effort measures as a function of signal to noise ratio (SNR). Younger adults with normal hearing (YNH, n = 24; experiment 1) and older adults with hearing impairment (n = 24; experiment 2) were recruited. Dual-task paradigms wherein the participants performed a primary speech recognition task simultaneously with a secondary task were conducted at a wide range of SNRs. Two different secondary tasks were used: an easy task (i.e., a simple visual reaction-time task) and a hard task (i.e., the incongruent Stroop test). The reaction time (RT) quantified the performance of the secondary task. For both participant groups and for both easy and hard secondary tasks, the curves that described the RT as a function of SNR were peak shaped. The RT increased as SNR changed from favorable to intermediate SNRs, and then decreased as SNRs moved from intermediate to unfavorable SNRs. The RT reached its peak (longest time) at the SNRs at which the participants could understand 30 to 50% of the speech. In experiments 1 and 2, the dual-task trials that had the same SNR were conducted in one block. To determine if the peak shape of the RT curves was specific to the blocked SNR presentation order used in these experiments, YNH participants were recruited (n = 25; experiment 3) and dual-task measures, wherein the SNR was varied from trial to trial (i.e., nonblocked), were conducted. The results indicated that, similar to the first two experiments, the RT curves had a peak shape. Secondary task performance was poorer at the intermediate SNRs than at the favorable and unfavorable SNRs. This pattern was observed for both YNH and older adults with hearing impairment participants and was not affected by either task type (easy or hard secondary task) or SNR presentation order (blocked or nonblocked). The shorter RT at the unfavorable SNRs (speech intelligibility < 30%) possibly reflects that the participants experienced cognitive overload and/or disengaged themselves from the listening task. The implication of using the dual-task paradigm as a listening effort measure is discussed.

Effect of a dual task on quantitative Timed Up and Go performance in community-dwelling older adults: A preliminary study.

PubMed

Smith, Erin; Walsh, Lorcan; Doyle, Julie; Greene, Barry; Blake, Catherine

2017-08-01

The Timed Up and Go test (TUG) is used as a measure of functional ability in older adults; however, the method of measurement does not allow us to determine which aspects of the test deficits occur in. The aim of the present study was to examine the ability of the quantitative TUG (QTUG) to measure performance during the TUG test under three different conditions - single task, motor task and cognitive dual task - and to compare performance between fallers and non-fallers in high-functioning community-dwelling older adults. A total of 37 community-dwelling older adults, 16 with a self-reported falls history in the previous year, were recruited. Participants underwent a falls risk assessment with a physiotherapist including the QTUG under three conditions (single task, motor task, cognitive dual-task). A total of 10 clinical parameters were chosen for analysis using mancova and a series of ancova, with age, sex and body mass index included as covariates. The mancova analysis showed a significant difference across the three task conditions (Wilk's Lambda F 20,186  = 3.37, P < 0.001. No overall significant difference between faller and non-faller groups (Wilk's Lambda F 10,96  = 1.469, P = 0.163) or significant interaction between task and faller status (Wilk's Lambda F 20,192  = 1.131, P = 0.321) was found. ancova results for each of the parameters showed overall differences between single, motor and cognitive tasks for all of the variables, except time in double support. When faller and non-faller differences were explored, cadence and stride velocity was greater, and stride time longer in those with a prior history of falls. In community-dwelling older adults, these preliminary results show that a cognitive dual-task significantly (P < 0.025) affects QTUG performance in almost all parameters, with a significant (P < 0.025) reduction in time-to-stand observed with a motor task. Although no statistical difference was found between fallers and non-fallers for many of the parameters, cadence, stride time and stride velocity were statistically different (P < 0.05). A larger sample size and more assessment points might lead to more definitive findings. These results highlight the need for further research to examine QTUG performance under dual-task conditions between fallers and non-fallers in this population, and to look at the ability of dual-task QTUG assessment to measure change longitudinally and the effectiveness of therapeutic interventions. Geriatr Gerontol Int 2017; 17: 1176-1182. © 2016 Japan Geriatrics Society.

Within-person relationship between self-efficacy and performance across trials. Effect of task objective and task type.

PubMed

Hepler, Teri J; Ritchie, Jason; Hill, Christopher R

2017-07-05

Self-efficacy has been shown to be a consistent, positive predictor of between-persons performance in sport. However, there have been equivocal results regarding the influence of self-efficacy on a person's performance over time. This study investigated the influence of self-efficacy on motor skill performance across trials with respect to two different task objectives and task types. Participants (N=84) performed 4 blocks of 10 trials of a dart throwing (closed skill) and a hitting (open skill) task under 2 different task objectives: competitive and goal-striving. For the goal-striving condition, success was defined as reaching a pre-determined performance level. The competitive condition involved competing against an opponent. Hierarchical linear modeling was used to examine the influence of past performance and self-efficacy on the within-person performance across multiple trials. Previous performance was negatively related with subsequent performance on all conditions. Self-efficacy was not a significant predictor of performance on any of the conditions. While task objective and task type did not moderate the efficacy-performance relationship in the current study, it is important to consider the role of other moderators in future research.

Clutter in electronic medical records: examining its performance and attentional costs using eye tracking.

PubMed

Moacdieh, Nadine; Sarter, Nadine

2015-06-01

The objective was to use eye tracking to trace the underlying changes in attention allocation associated with the performance effects of clutter, stress, and task difficulty in visual search and noticing tasks. Clutter can degrade performance in complex domains, yet more needs to be known about the associated changes in attention allocation, particularly in the presence of stress and for different tasks. Frequently used and relatively simple eye tracking metrics do not effectively capture the various effects of clutter, which is critical for comprehensively analyzing clutter and developing targeted, real-time countermeasures. Electronic medical records (EMRs) were chosen as the application domain for this research. Clutter, stress, and task difficulty were manipulated, and physicians' performance on search and noticing tasks was recorded. Several eye tracking metrics were used to trace attention allocation throughout those tasks, and subjective data were gathered via a debriefing questionnaire. Clutter degraded performance in terms of response time and noticing accuracy. These decrements were largely accentuated by high stress and task difficulty. Eye tracking revealed the underlying attentional mechanisms, and several display-independent metrics were shown to be significant indicators of the effects of clutter. Eye tracking provides a promising means to understand in detail (offline) and prevent (in real time) major performance breakdowns due to clutter. Display designers need to be aware of the risks of clutter in EMRs and other complex displays and can use the identified eye tracking metrics to evaluate and/or adjust their display. © 2015, Human Factors and Ergonomics Society.

Usability assessment of an electronic health record in a comprehensive dental clinic.

PubMed

Suebnukarn, Siriwan; Rittipakorn, Pawornwan; Thongyoi, Budsara; Boonpitak, Kwanwong; Wongsapai, Mansuang; Pakdeesan, Panu

2013-12-01

In this paper we present the development and usability of an electronic health record (EHR) system in a comprehensive dental clinic.The graphic user interface of the system was designed to consider the concept of cognitive ergonomics.The cognitive task analysis was used to evaluate the user interface of the EHR by identifying all sub-tasks and classifying them into mental or physical operators, and to predict task execution time required to perform the given task. We randomly selected 30 cases that had oral examinations for routine clinical care in a comprehensive dental clinic. The results were based on the analysis of 4 prototypical tasks performed by ten EHR users. The results showed that on average a user needed to go through 27 steps to complete all tasks for one case. To perform all 4 tasks of 30 cases, they spent about 91 min (independent of system response time) for data entry, of which 51.8 min were spent on more effortful mental operators. In conclusion, the user interface can be improved by reducing the percentage of mental effort required for the tasks.

Visual scanning with or without spatial uncertainty and time-sharing performance

NASA Technical Reports Server (NTRS)

Liu, Yili; Wickens, Christopher D.

1989-01-01

An experiment is reported that examines the pattern of task interference between visual scanning as a sequential and selective attention process and other concurrent spatial or verbal processing tasks. A distinction is proposed between visual scanning with or without spatial uncertainty regarding the possible differential effects of these two types of scanning on interference with other concurrent processes. The experiment required the subject to perform a simulated primary tracking task, which was time-shared with a secondary spatial or verbal decision task. The relevant information that was needed to perform the decision tasks were displayed with or without spatial uncertainty. The experiment employed a 2 x 2 x 2 design with types of scanning (with or without spatial uncertainty), expected scanning distance (low/high), and codes of concurrent processing (spatial/verbal) as the three experimental factors. The results provide strong evidence that visual scanning as a spatial exploratory activity produces greater task interference with concurrent spatial tasks than with concurrent verbal tasks. Furthermore, spatial uncertainty in visual scanning is identified to be the crucial factor in producing this differential effect.

The role of memory representation in the vigilance decrement

PubMed Central

CAGGIANO, DANIEL M.; PARASURAMAN, RAJA

2005-01-01

Working memory load is critically important for the overall level of performance on vigilance tasks. However, its role in a key aspect of vigilance—sensitivity decrement over time—is unclear. We used a dual-task procedure in which either a spatial or a nonspatial working memory task was performed simultaneously with a spatial vigilance task for 20 min. Sensitivity in the vigilance task declined over time when the concurrent task involved spatial working memory. In contrast, there was no sensitivity decrement with a nonspatial working memory task. The results provide the first evidence of a specific role for working memory representation in vigilance decrement. The findings are also consistent with a multiple resource theory in which separate resources for memory representation and cognitive control operations are differentially susceptible to depletion over time, depending on the demands of the task at hand. PMID:15732706

Task feedback effects on conflict monitoring and executive control: relationship to subclinical measures of depression.

PubMed

Holmes, Avram J; Pizzagalli, Diego A

2007-02-01

Emerging evidence suggests that depression is associated with executive dysfunction, particularly after committing errors or receiving negative performance feedback. To test this hypothesis, 57 participants performed two executive tasks known to elicit errors (the Simon and Stroop Tasks) during positive or negative performance feedback. Participants with elevated depressive symptoms (Beck Depression Inventory scores >or= 13) were characterized by impaired posterror and postconflict performance adjustments, especially during emotionally negative task-related feedback. Additionally, for both tasks, depressive symptoms were inversely related to postconflict reaction time adjustments following negative, but not positive, feedback. These findings suggest that subclinical depression is associated with impairments in behavioral adjustments after internal (perceived failure) and external feedback about deficient task performance. (c) 2007 APA, all rights reserved.

Apollo 16 time and motion study

NASA Technical Reports Server (NTRS)

Kubis, J. F.; Elrod, J. T.; Rusnak, R.; Barnes, J. E.; Saxon, S. C.

1972-01-01

A time and motion study is presented of astronaut lunar surface activity on Apollo 16 which consists of five distinct analyses: an evaluation of lunar mobility, a comparison of task performance in 1-g training and lunar EVA, a study of metabolic costs and adaptation, a discussion of falls, and retrieval of fallen objects. Two basic mobility patterns, the hop or canter and the traditional walking gait, were consistently utilized in longer traverses. The metabolic rates associated with these two mobility types, each used by a different astronaut, were relatively equivalent. The time to perform tasks on the lunar surface was significantly longer (on the order of 70%) than the time to perform the same tasks during the last 1-g training session. These results corroborated the findings on Apollo 15 and were not significantly different from them. There was general improvement in lunar EVA performance upon repetition of tasks. Metabolic rate (BTU/hr.) and metabolic cost (BTU) decreased over successive EVAs. Specifically, the metabolic rate associated with riding the lunar roving vehicle (LRV) decreased by approximately 18% from EVA 1 to EVA 2 and by 15% from EVA 2 to EVA 3.

The effect of mental fatigue on sustained attention: an fNIRS study

NASA Astrophysics Data System (ADS)

Zhang, Zhen; Yang, Hanjun; Cao, Yong; Xu, Fenggang; Jiang, Jin; Jiao, Xuejun

2017-01-01

Sustained attention is the ability to keep focused and vigilance for long time in external stimulation, which was crucial in safe-critical human-machine system. While the ability of sustained attention will decline because of mental fatigue, even lead to serious accidents in fatigue state. Therefore, it is of great significance to explore the impact of fatigue on sustained attention. Functional Near-Infrared Spectroscopy (fNIRS) can measure cerebral hemoglobin in order to reflect cognitive function indirectly. In previous related fatigue studies, monotonous and long-time CPT (continuous performance test task) was often used to explore the performance change and brain activity, but the effect of time on task (TOT) was always involved. In this study, in order to avoid the TOT effect, the sustained attention task and fatigue task were separated. It was adopted in the study that the modified continuous performance test (CPT) was chosen as the sustained attention task and verbal 2-back task as the fatigue induced task. The fNIRS signals were extracted from 10 channels in the prefrontal cortex (PFC) from 20 healthy subjects. Studies found that cerebral lateralization increased significantly from alert to fatigue state in sustained attention task. Besides, Average oxyhemoglobin (HBO) of PFC increased significantly from alert to fatigue task, and the spatial pattern of activity of oxyhemoglobin also changed, which c be sensitive features to fatigue detection.

Divided attention and mental effort after severe traumatic brain injury.

PubMed

Azouvi, Philippe; Couillet, Josette; Leclercq, Michel; Martin, Yves; Asloun, Sybille; Rousseaux, Marc

2004-01-01

The aim of this study was to assess dual-task performance in TBI patients, under different experimental conditions, with or without explicit emphasis on one of two tasks. Results were compared with measurement of the subjective mental effort required to perform each task. Forty-three severe TBI patients at the subacute or chronic phase performed two tasks under single- and dual-task conditions: (a) random generation; (b) visual go-no go reaction time task. Three dual-task conditions were given, requiring either to consider both tasks as equally important or to focus preferentially on one of them. Patients were compared to matched controls. Subjective mental effort was rated on a visual analogic scale. TBI patients showed a disproportionate increase in reaction time in the go-no go task under the dual-task condition. However, they were just as able as controls to adapt performance to the specific instructions about the task to be emphasised. Patients reported significantly higher subjective mental effort, but the variation of mental effort according to task condition was similar to that of controls. These results suggest that the divided attention deficit of TBI patients is related to a reduction in available processing resources rather than an impairment of strategic processes responsible for attentional allocation and switching. The higher level of subjective mental effort may explain why TBI patients frequently complain of mental fatigue, although this subjective complaint seems to be relatively independent of cognitive impairment.

Driving monotonous routes in a train simulator: the effect of task demand on driving performance and subjective experience.

PubMed

Dunn, Naomi; Williamson, Ann

2012-01-01

Although monotony is widely recognised as being detrimental to performance, its occurrence and effects are not yet well understood. This is despite the fact that task-related characteristics, such as monotony and low task demand, have been shown to contribute to performance decrements over time. Participants completed one of two simulated train-driving scenarios. Both were highly monotonous and differed only in terms of the level of cognitive demand required (i.e. low demand or high demand). These results highlight the seriously detrimental effects of the combination of monotony and low task demands and clearly show that even a relatively minor increase in cognitive demand can mitigate adverse monotony-related effects on performance for extended periods of time. Monotony is an inherent characteristic of transport industries, including rail, aviation and road transport, which can have adverse impact on safety, reliability and efficiency. This study highlights possible strategies for mitigating these adverse effects. Practitioner Summary: This study provides evidence for the importance of cognitive demand in mitigating monotony-related effects on performance. The results have clear implications for the rapid onset of performance deterioration in low demand monotonous tasks and demonstrate that these detrimental performance effects can be overcome with simple solutions, such as making the task more cognitively engaging.

Task and work performance on Skylab missions 2, 3, and 4: Time and motion study: Experiment M151

NASA Technical Reports Server (NTRS)

Kubis, J. F.; Mclaughlin, E. J.; Jackson, J. M.; Rusnak, R.; Mcbride, G. H.; Saxon, S. V.

1977-01-01

Human task performance was evaluated under weightlessness conditions during long duration space flight in order to study the characteristics of the adaptation function. Results show that despite pronounced variability in training schedules and in initial reaction to the Skylab environment, in-flight task performance was relatively equivalent among Skylab crews, and behavioral performance continued to improve from beginning to end of all missions.

Multiple-Task Performance: A Critical Review of the Literature and a Cognitive Neuroscience Framework

DTIC Science & Technology

1994-03-10

determine capacity variations as shown in dual-task performance. In addition, neurobiology and psychological evidence shows that the nervous system is...do we perform complex tasks requiring two or more activities in a short period of time and what determines the quality of performance? Psychological ...definition for these kinds of entities. Introduction of the computer metaphor in cognitive psychology , ascribing behavioral capacity limitations to a kind

Distraction during learning with hypermedia: difficult tasks help to keep task goals on track

PubMed Central

Scheiter, Katharina; Gerjets, Peter; Heise, Elke

2014-01-01

In educational hypermedia environments, students are often confronted with potential sources of distraction arising from additional information that, albeit interesting, is unrelated to their current task goal. The paper investigates the conditions under which distraction occurs and hampers performance. Based on theories of volitional action control it was hypothesized that interesting information, especially if related to a pending goal, would interfere with task performance only when working on easy, but not on difficult tasks. In Experiment 1, 66 students learned about probability theory using worked examples and solved corresponding test problems, whose task difficulty was manipulated. As a second factor, the presence of interesting information unrelated to the primary task was varied. Results showed that students solved more easy than difficult probability problems correctly. However, the presence of interesting, but task-irrelevant information did not interfere with performance. In Experiment 2, 68 students again engaged in example-based learning and problem solving in the presence of task-irrelevant information. Problem-solving difficulty was varied as a first factor. Additionally, the presence of a pending goal related to the task-irrelevant information was manipulated. As expected, problem-solving performance declined when a pending goal was present during working on easy problems, whereas no interference was observed for difficult problems. Moreover, the presence of a pending goal reduced the time on task-relevant information and increased the time on task-irrelevant information while working on easy tasks. However, as revealed by mediation analyses these changes in overt information processing behavior did not explain the decline in problem-solving performance. As an alternative explanation it is suggested that goal conflicts resulting from pending goals claim cognitive resources, which are then no longer available for learning and problem solving. PMID:24723907

A continuous time-resolved measure decoded from EEG oscillatory activity predicts working memory task performance.

PubMed

Astrand, Elaine

2018-06-01

Working memory (WM), crucial for successful behavioral performance in most of our everyday activities, holds a central role in goal-directed behavior. As task demands increase, inducing higher WM load, maintaining successful behavioral performance requires the brain to work at the higher end of its capacity. Because it is depending on both external and internal factors, individual WM load likely varies in a continuous fashion. The feasibility to extract such a continuous measure in time that correlates to behavioral performance during a working memory task remains unsolved. Multivariate pattern decoding was used to test whether a decoder constructed from two discrete levels of WM load can generalize to produce a continuous measure that predicts task performance. Specifically, a linear regression with L2-regularization was chosen with input features from EEG oscillatory activity recorded from healthy participants while performing the n-back task, [Formula: see text]. The feasibility to extract a continuous time-resolved measure that correlates positively to trial-by-trial working memory task performance is demonstrated (r  =  0.47, p  <  0.05). It is furthermore shown that this measure allows to predict task performance before action (r  =  0.49, p  <  0.05). We show that the extracted continuous measure enables to study the temporal dynamics of the complex activation pattern of WM encoding during the n-back task. Specifically, temporally precise contributions of different spectral features are observed which extends previous findings of traditional univariate approaches. These results constitute an important contribution towards a wide range of applications in the field of cognitive brain-machine interfaces. Monitoring mental processes related to attention and WM load to reduce the risk of committing errors in high-risk environments could potentially prevent many devastating consequences or using the continuous measure as neurofeedback opens up new possibilities to develop novel rehabilitation techniques for individuals with degraded WM capacity.

A continuous time-resolved measure decoded from EEG oscillatory activity predicts working memory task performance

NASA Astrophysics Data System (ADS)

Astrand, Elaine

2018-06-01

Objective. Working memory (WM), crucial for successful behavioral performance in most of our everyday activities, holds a central role in goal-directed behavior. As task demands increase, inducing higher WM load, maintaining successful behavioral performance requires the brain to work at the higher end of its capacity. Because it is depending on both external and internal factors, individual WM load likely varies in a continuous fashion. The feasibility to extract such a continuous measure in time that correlates to behavioral performance during a working memory task remains unsolved. Approach. Multivariate pattern decoding was used to test whether a decoder constructed from two discrete levels of WM load can generalize to produce a continuous measure that predicts task performance. Specifically, a linear regression with L2-regularization was chosen with input features from EEG oscillatory activity recorded from healthy participants while performing the n-back task, n\\in [1,2] . Main results. The feasibility to extract a continuous time-resolved measure that correlates positively to trial-by-trial working memory task performance is demonstrated (r  =  0.47, p  <  0.05). It is furthermore shown that this measure allows to predict task performance before action (r  =  0.49, p  <  0.05). We show that the extracted continuous measure enables to study the temporal dynamics of the complex activation pattern of WM encoding during the n-back task. Specifically, temporally precise contributions of different spectral features are observed which extends previous findings of traditional univariate approaches. Significance. These results constitute an important contribution towards a wide range of applications in the field of cognitive brain–machine interfaces. Monitoring mental processes related to attention and WM load to reduce the risk of committing errors in high-risk environments could potentially prevent many devastating consequences or using the continuous measure as neurofeedback opens up new possibilities to develop novel rehabilitation techniques for individuals with degraded WM capacity.

Deficits in Coordinative Bimanual Timing Precision in Children With Specific Language Impairment

PubMed Central

Goffman, Lisa; Zelaznik, Howard N.

2017-01-01

Purpose Our objective was to delineate components of motor performance in specific language impairment (SLI); specifically, whether deficits in timing precision in one effector (unimanual tapping) and in two effectors (bimanual clapping) are observed in young children with SLI. Method Twenty-seven 4- to 5-year-old children with SLI and 21 age-matched peers with typical language development participated. All children engaged in a unimanual tapping and a bimanual clapping timing task. Standard measures of language and motor performance were also obtained. Results No group differences in timing variability were observed in the unimanual tapping task. However, compared with typically developing peers, children with SLI were more variable in their timing precision in the bimanual clapping task. Nine of the children with SLI performed greater than 1 SD below the mean on a standardized motor assessment. The children with low motor performance showed the same profile as observed across all children with SLI, with unaffected unimanual and impaired bimanual timing precision. Conclusions Although unimanual timing is unaffected, children with SLI show a deficit in timing that requires bimanual coordination. We propose that the timing deficits observed in children with SLI are associated with the increased demands inherent in bimanual performance. PMID:28174821

Simulator study of the effect of visual-motion time delays on pilot tracking performance with an audio side task

NASA Technical Reports Server (NTRS)

Riley, D. R.; Miller, G. K., Jr.

1978-01-01

The effect of time delay was determined in the visual and motion cues in a flight simulator on pilot performance in tracking a target aircraft that was oscillating sinusoidally in altitude only. An audio side task was used to assure the subject was fully occupied at all times. The results indicate that, within the test grid employed, about the same acceptable time delay (250 msec) was obtained for a single aircraft (fighter type) by each of two subjects for both fixed-base and motion-base conditions. Acceptable time delay is defined as the largest amount of delay that can be inserted simultaneously into the visual and motion cues before performance degradation occurs. A statistical analysis of the data was made to establish this value of time delay. Audio side task provided quantitative data that documented the subject's work level.

Performance evaluation of a six-axis generalized force-reflecting teleoperator

NASA Technical Reports Server (NTRS)

Hannaford, B.; Wood, L.; Guggisberg, B.; Mcaffee, D.; Zak, H.

1989-01-01

Work in real-time distributed computation and control has culminated in a prototype force-reflecting telemanipulation system having a dissimilar master (cable-driven, force-reflecting hand controller) and a slave (PUMA 560 robot with custom controller), an extremely high sampling rate (1000 Hz), and a low loop computation delay (5 msec). In a series of experiments with this system and five trained test operators covering over 100 hours of teleoperation, performance was measured in a series of generic and application-driven tasks with and without force feedback, and with control shared between teleoperation and local sensor referenced control. Measurements defining task performance included 100-Hz recording of six-axis force/torque information from the slave manipulator wrist, task completion time, and visual observation of predefined task errors. The task consisted of high precision peg-in-hole insertion, electrical connectors, velcro attach-de-attach, and a twist-lock multi-pin connector. Each task was repeated three times under several operating conditions: normal bilateral telemanipulation, forward position control without force feedback, and shared control. In shared control, orientation was locally servo controlled to comply with applied torques, while translation was under operator control. All performance measures improved as capability was added along a spectrum of capabilities ranging from pure position control through force-reflecting teleoperation and shared control. Performance was optimal for the bare-handed operator.

Male Smokers' and Non-Smokers' Response Inhibition in Go/No-Go Tasks: Effect of Three Task Parameters

PubMed Central

Zhao, Xin; Liu, Xiaoting; Zan, Xiangyi; Jin, Ge; Maes, Joseph H. R.

2016-01-01

Impaired response inhibition plays a major role in many addictive behaviors. However, in studies using go/no-go tasks, findings regarding the presence of response inhibition deficits in nicotine-dependent individuals are mixed. This might be due to differences between studies on a number of task parameters. Here we aimed to identify task conditions under which go/no-go task performance deficits can be observed in smokers and to characterize the nature of such deficits. Sixty-one male students (30 smokers, 31 non-smokers) performed a go/no-go task while independently manipulating three task parameters: (1) percentage no-go trials (50% or 25%), (2) stimulus presentation time (600 ms or 200 ms), and (3) nature of no-go stimuli (cigarette related or cigarette unrelated). Three measures, reaction time on go trials and percentage correct responses on go and no-go trials, served as performance indicators. Under 200-ms but not 600-ms stimulus presentation conditions, the smokers responded faster on go trials and made more errors on both go and no-go trials than the non-smokers did. These differences occurred irrespective of the percentage of no-go trials and nature of no-go stimuli. The accuracy differences disappeared after controlling for the response time differences, suggesting a strong speed-accuracy trade-off. This study contributes to unraveling the conditions under which smokers display impaired inhibition performance and helps to characterize the nature of this impairment. Under task conditions prompting fast responding, smokers are more prone to increase response speed and to make more errors than non-smokers. PMID:27500831

Short-term motor learning through non-immersive virtual reality task in individuals with down syndrome.

PubMed

de Mello Monteiro, Carlos Bandeira; da Silva, Talita Dias; de Abreu, Luiz Carlos; Fregni, Felipe; de Araujo, Luciano Vieira; Ferreira, Fernando Henrique Inocêncio Borba; Leone, Claudio

2017-04-14

Down syndrome (DS) has unique physical, motor and cognitive characteristics. Despite cognitive and motor difficulties, there is a possibility of intervention based on the knowledge of motor learning. However, it is important to study the motor learning process in individuals with DS during a virtual reality task to justify the use of virtual reality to organize intervention programs. The aim of this study was to analyze the motor learning process in individuals with DS during a virtual reality task. A total of 40 individuals participated in this study, 20 of whom had DS (24 males and 8 females, mean age of 19 years, ranging between 14 and 30 yrs.) and 20 typically developing individuals (TD) who were matched by age and gender to the individuals with DS. To examine this issue, we used software that uses 3D images and reproduced a coincidence-timing task. The results showed that all individuals improved performance in the virtual task, but the individuals with DS that started the task with worse performance showed higher difference from the beginning. Besides that, they were able to retain and transfer the performance with increase of speed of the task. Individuals with DS are able to learn movements from virtual tasks, even though the movement time was higher compared to the TD individuals. The results showed that individuals with DS who started with low performance improved coincidence- timing task with virtual objects, but were less accurate than typically developing individuals. ClinicalTrials.gov Identifier: NCT02719600 .

Quantifying usability: an evaluation of a diabetes mHealth system on effectiveness, efficiency, and satisfaction metrics with associated user characteristics.

PubMed

Georgsson, Mattias; Staggers, Nancy

2016-01-01

Mobile health (mHealth) systems are becoming more common for chronic disease management, but usability studies are still needed on patients' perspectives and mHealth interaction performance. This deficiency is addressed by our quantitative usability study of a mHealth diabetes system evaluating patients' task performance, satisfaction, and the relationship of these measures to user characteristics. We used metrics in the International Organization for Standardization (ISO) 9241-11 standard. After standardized training, 10 patients performed representative tasks and were assessed on individual task success, errors, efficiency (time on task), satisfaction (System Usability Scale [SUS]) and user characteristics. Tasks of exporting and correcting values proved the most difficult, had the most errors, the lowest task success rates, and consumed the longest times on task. The average SUS satisfaction score was 80.5, indicating good but not excellent system usability. Data trends showed males were more successful in task completion, and younger participants had higher performance scores. Educational level did not influence performance, but a more recent diabetes diagnosis did. Patients with more experience in information technology (IT) also had higher performance rates. Difficult task performance indicated areas for redesign. Our methods can assist others in identifying areas in need of improvement. Data about user background and IT skills also showed how user characteristics influence performance and can provide future considerations for targeted mHealth designs. Using the ISO 9241-11 usability standard, the SUS instrument for satisfaction and measuring user characteristics provided objective measures of patients' experienced usability. These could serve as an exemplar for standardized, quantitative methods for usability studies on mHealth systems. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association.

Quantifying usability: an evaluation of a diabetes mHealth system on effectiveness, efficiency, and satisfaction metrics with associated user characteristics

PubMed Central

Staggers, Nancy

2016-01-01

Objective Mobile health (mHealth) systems are becoming more common for chronic disease management, but usability studies are still needed on patients’ perspectives and mHealth interaction performance. This deficiency is addressed by our quantitative usability study of a mHealth diabetes system evaluating patients’ task performance, satisfaction, and the relationship of these measures to user characteristics. Materials and Methods We used metrics in the International Organization for Standardization (ISO) 9241-11 standard. After standardized training, 10 patients performed representative tasks and were assessed on individual task success, errors, efficiency (time on task), satisfaction (System Usability Scale [SUS]) and user characteristics. Results Tasks of exporting and correcting values proved the most difficult, had the most errors, the lowest task success rates, and consumed the longest times on task. The average SUS satisfaction score was 80.5, indicating good but not excellent system usability. Data trends showed males were more successful in task completion, and younger participants had higher performance scores. Educational level did not influence performance, but a more recent diabetes diagnosis did. Patients with more experience in information technology (IT) also had higher performance rates. Discussion Difficult task performance indicated areas for redesign. Our methods can assist others in identifying areas in need of improvement. Data about user background and IT skills also showed how user characteristics influence performance and can provide future considerations for targeted mHealth designs. Conclusion Using the ISO 9241-11 usability standard, the SUS instrument for satisfaction and measuring user characteristics provided objective measures of patients’ experienced usability. These could serve as an exemplar for standardized, quantitative methods for usability studies on mHealth systems. PMID:26377990

Effects of age and auditory and visual dual tasks on closed-road driving performance.

PubMed

Chaparro, Alex; Wood, Joanne M; Carberry, Trent

2005-08-01

This study investigated how driving performance of young and old participants is affected by visual and auditory secondary tasks on a closed driving course. Twenty-eight participants comprising two age groups (younger, mean age = 27.3 years; older, mean age = 69.2 years) drove around a 5.1-km closed-road circuit under both single and dual task conditions. Measures of driving performance included detection and identification of road signs, detection and avoidance of large low-contrast road hazards, gap judgment, lane keeping, and time to complete the course. The dual task required participants to verbally report the sums of pairs of single-digit numbers presented through either a computer speaker (auditorily) or a dashboard-mounted monitor (visually) while driving. Participants also completed a vision and cognitive screening battery, including LogMAR visual acuity, Pelli-Robson letter contrast sensitivity, the Trails test, and the Digit Symbol Substitution (DSS) test. Drivers reported significantly fewer signs, hit more road hazards, misjudged more gaps, and increased their time to complete the course under the dual task (visual and auditory) conditions compared with the single task condition. The older participants also reported significantly fewer road signs and drove significantly more slowly than the younger participants, and this was exacerbated for the visual dual task condition. The results of the regression analysis revealed that cognitive aging (measured by the DSS and Trails test) rather than chronologic age was a better predictor of the declines seen in driving performance under dual task conditions. An overall z score was calculated, which took into account both driving and the secondary task (summing) performance under the two dual task conditions. Performance was significantly worse for the auditory dual task compared with the visual dual task, and the older participants performed significantly worse than the young subjects. These findings demonstrate that multitasking had a significant detrimental impact on driving performance and that cognitive aging was the best predictor of the declines seen in driving performance under dual task conditions. These results have implications for use of mobile phones or in-vehicle navigational devices while driving, especially for older adults.

Dual Task of Fine Motor Skill and Problem Solving in Individuals With Multiple Sclerosis: A Pilot Study.

PubMed

Goverover, Y; Sandroff, B M; DeLuca, J

2018-04-01

To (1) examine and compare dual-task performance in patients with multiple sclerosis (MS) and healthy controls (HCs) using mathematical problem-solving questions that included an everyday competence component while performing an upper extremity fine motor task; and (2) examine whether difficulties in dual-task performance are associated with problems in performing an everyday internet task. Pilot study, mixed-design with both a within and between subjects' factor. A nonprofit rehabilitation research institution and the community. Participants (N=38) included persons with MS (n=19) and HCs (n=19) who were recruited from a nonprofit rehabilitation research institution and from the community. Not applicable. Participant were presented with 2 testing conditions: (1) solving mathematical everyday problems or placing bolts into divots (single-task condition); and (2) solving problems while putting bolts into divots (dual-task condition). Additionally, participants were required to perform a test of everyday internet competence. As expected, dual-task performance was significantly worse than either of the single-task tasks (ie, number of bolts into divots or correct answers, and time to answer the questions). Cognitive but not motor dual-task cost was associated with worse performance in activities of everyday internet tasks. Cognitive dual-task cost is significantly associated with worse performance of everyday technology. This was not observed in the motor dual-task cost. The implications of dual-task costs on everyday activity are discussed. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

The reaction times of drivers aged 20 to 80 during a divided attention driving.

PubMed

Svetina, Matija

2016-11-16

Many studies addressing age-related changes in driving performance focus on comparing young vs. older drivers, which might lead to the biased conclusion that driving performance decreases only after the age of 65. The main aim of the study was to show that changes in driving performance are progressive throughout the adult years. A sample of 351 drivers aged 20 to 80 was assessed for their reaction times while driving between road cones. The drivers were exposed to 2 conditions varying according to task complexity. In single task conditions, the drivers performed a full stopping maneuver at a given signal; in dual task conditions, the drivers were distracted before the signal for stopping maneuver was triggered. Reaction times were compared across conditions and age groups. The results showed that both reaction times and variability of driving performance increased progressively between the ages of 20 and 80. The increase in both reaction times and variability was greater in the complex task condition. The high-performing quarter of elderly drivers performed equally well or better than younger drivers did. The data clearly supported the claim that driving performance changes steadily across age groups: both mean reaction time and interindividual variability progressively increase with age. In addition, a significant group of older drivers was identified who did not show the expected age-related decrease in performance. The findings have important implications, suggesting that in relation to driving, aging is a progressive phenomenon and may lead to variety of driving performance; age-related studies of driving performance should put more emphasis on investigating changes across the whole driver age range rather than only comparing younger and older drivers.

Different motor tasks impact differently on cognitive performance of older persons during dual task tests.

PubMed

Simoni, David; Rubbieri, Gaia; Baccini, Marco; Rinaldi, Lucio; Becheri, Dimitri; Forconi, Tatiana; Mossello, Enrico; Zanieri, Samanta; Marchionni, Niccolò; Di Bari, Mauro

2013-07-01

Dual task paradigm states that the introduction of a second task during a cognitive or motor performance results in a decreased performance in either task. Treadmill walk, often used in clinical applications of dual task testing, has never been compared to overground walk, to ascertain its susceptibility to interference from a second task. We compared the effects of overground and treadmill gait on dual task performance. Gait kinematic parameters and cognitive performance were obtained in 29 healthy older adults (mean age 75 years, 14 females) when they were walking freely on a sensorized carpet or during treadmill walking with an optoelectronic system, in single task or dual task conditions, using alternate repetition of letters as a cognitive verbal task. During overground walking, speed, cadence, step length stride length, and double support time (all with P value<0.001) and cognitive performance (number of correct words, P<0.001) decreased substantially from single to dual task testing. When subjects walked at a fixed speed on the treadmill, cadence decreased significantly (P=0.005), whereas cognitive performance remained unaffected. Both motor and cognitive performances decline during dual task testing with overground walking. Conversely, cognitive performance remains unaffected in dual task testing on the treadmill. In the light of current dual task paradigm, these findings may have relevant implication for our understanding of motor control, as they suggest that treadmill walk does not involve brain areas susceptible to interference from the introduction of a cognitive task. Copyright © 2013 Elsevier Ltd. All rights reserved.

Classification of EEG signals to identify variations in attention during motor task execution.

PubMed

Aliakbaryhosseinabadi, Susan; Kamavuako, Ernest Nlandu; Jiang, Ning; Farina, Dario; Mrachacz-Kersting, Natalie

2017-06-01

Brain-computer interface (BCI) systems in neuro-rehabilitation use brain signals to control external devices. User status such as attention affects BCI performance; thus detecting the user's attention drift due to internal or external factors is essential for high detection accuracy. An auditory oddball task was applied to divert the users' attention during a simple ankle dorsiflexion movement. Electroencephalogram signals were recorded from eighteen channels. Temporal and time-frequency features were projected to a lower dimension space and used to analyze the effect of two attention levels on motor tasks in each participant. Then, a global feature distribution was constructed with the projected time-frequency features of all participants from all channels and applied for attention classification during motor movement execution. Time-frequency features led to significantly better classification results with respect to the temporal features, particularly for electrodes located over the motor cortex. Motor cortex channels had a higher accuracy in comparison to other channels in the global discrimination of attention level. Previous methods have used the attention to a task to drive external devices, such as the P300 speller. However, here we focus for the first time on the effect of attention drift while performing a motor task. It is possible to explore user's attention variation when performing motor tasks in synchronous BCI systems with time-frequency features. This is the first step towards an adaptive real-time BCI with an integrated function to reveal attention shifts from the motor task. Copyright © 2017 Elsevier B.V. All rights reserved.

Over the hill at 24: persistent age-related cognitive-motor decline in reaction times in an ecologically valid video game task begins in early adulthood.

PubMed

Thompson, Joseph J; Blair, Mark R; Henrey, Andrew J

2014-01-01

Typically studies of the effects of aging on cognitive-motor performance emphasize changes in elderly populations. Although some research is directly concerned with when age-related decline actually begins, studies are often based on relatively simple reaction time tasks, making it impossible to gauge the impact of experience in compensating for this decline in a real world task. The present study investigates age-related changes in cognitive motor performance through adolescence and adulthood in a complex real world task, the real-time strategy video game StarCraft 2. In this paper we analyze the influence of age on performance using a dataset of 3,305 players, aged 16-44, collected by Thompson, Blair, Chen & Henrey [1]. Using a piecewise regression analysis, we find that age-related slowing of within-game, self-initiated response times begins at 24 years of age. We find no evidence for the common belief expertise should attenuate domain-specific cognitive decline. Domain-specific response time declines appear to persist regardless of skill level. A second analysis of dual-task performance finds no evidence of a corresponding age-related decline. Finally, an exploratory analyses of other age-related differences suggests that older participants may have been compensating for a loss in response speed through the use of game mechanics that reduce cognitive load.

Over the Hill at 24: Persistent Age-Related Cognitive-Motor Decline in Reaction Times in an Ecologically Valid Video Game Task Begins in Early Adulthood

PubMed Central

Thompson, Joseph J.; Blair, Mark R.; Henrey, Andrew J.

2014-01-01

Typically studies of the effects of aging on cognitive-motor performance emphasize changes in elderly populations. Although some research is directly concerned with when age-related decline actually begins, studies are often based on relatively simple reaction time tasks, making it impossible to gauge the impact of experience in compensating for this decline in a real world task. The present study investigates age-related changes in cognitive motor performance through adolescence and adulthood in a complex real world task, the real-time strategy video game StarCraft 2. In this paper we analyze the influence of age on performance using a dataset of 3,305 players, aged 16-44, collected by Thompson, Blair, Chen & Henrey [1]. Using a piecewise regression analysis, we find that age-related slowing of within-game, self-initiated response times begins at 24 years of age. We find no evidence for the common belief expertise should attenuate domain-specific cognitive decline. Domain-specific response time declines appear to persist regardless of skill level. A second analysis of dual-task performance finds no evidence of a corresponding age-related decline. Finally, an exploratory analyses of other age-related differences suggests that older participants may have been compensating for a loss in response speed through the use of game mechanics that reduce cognitive load. PMID:24718593

Functional performance comparison between real and virtual tasks in older adults

PubMed Central

Bezerra, Ítalla Maria Pinheiro; Crocetta, Tânia Brusque; Massetti, Thais; da Silva, Talita Dias; Guarnieri, Regiani; Meira, Cassio de Miranda; Arab, Claudia; de Abreu, Luiz Carlos; de Araujo, Luciano Vieira; Monteiro, Carlos Bandeira de Mello

2018-01-01

Abstract Introduction: Ageing is usually accompanied by deterioration of physical abilities, such as muscular strength, sensory sensitivity, and functional capacity, making chronic diseases, and the well-being of older adults new challenges to global public health. Objective: The purpose of this study was to evaluate whether a task practiced in a virtual environment could promote better performance and enable transfer to the same task in a real environment. Method: The study evaluated 65 older adults of both genders, aged 60 to 82 years (M = 69.6, SD = 6.3). A timing coincident task was applied to measure the perceptual-motor ability to perform a motor response. The participants were divided into 2 groups: started in a real interface and started in a virtual interface. Results: All subjects improved their performance during the practice, but improvement was not observed for the real interface, as the participants were near maximum performance from the beginning of the task. However, there was no transfer of performance from the virtual to real environment or vice versa. Conclusions: The virtual environment was shown to provide improvement of performance with a short-term motor learning protocol in a timing coincident task. This result suggests that the practice of tasks in a virtual environment seems to be a promising tool for the assessment and training of healthy older adults, even though there was no transfer of performance to a real environment. Trial registration: ISRCTN02960165. Registered 8 November 2016. PMID:29369177

77 FR 12907 - Visual-Manual NHTSA Driver Distraction Guidelines for In-Vehicle Electronic Devices

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-02

... impact of task performance while driving on driving safety and time-based acceptance criteria for... feedback). The proposed NHTSA Guidelines list certain secondary, non-driving related tasks that, based on... cannot be used by the driver to perform such tasks while the driver is driving. For all other secondary...

Evaluation of target scores and benchmarks for the traversal task scenario of the Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR) laparoscopy simulator.

PubMed

Hackethal, A; Immenroth, M; Bürger, T

2006-04-01

The Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR) simulator is validated for laparoscopy training, but benchmarks and target scores for assessing single tasks are needed. Control data for the MIST-VR traversal task scenario were collected from 61 novices who performed the task 10 times over 3 days (1 h daily). Data were collected on the time taken, error score, economy of movement, and total score. Test differences were analyzed through percentage scores and t-tests for paired samples. Improvement was greatest over tests 1 to 5 (improvement: test(1.2), 38.07%; p = 0.000; test(4.5), 10.66%; p = 0.010): between tests 5 and 10, improvement slowed and scores stabilized. Variation in participants' performance fell steadily over the 10 tests. Trainees should perform at least 10 tests of the traversal task-five to get used to the equipment and task (automation phase; target total score, 95.16) and five to stabilize and consolidate performance (test 10 target total score, 74.11).

Manipulating flexible parts using a teleoperated system with time delay: An experiment

NASA Technical Reports Server (NTRS)

Kotoku, T.; Takamune, K.; Tanie, K.; Komoriya, K.; Matsuhira, N.; Asakura, M.; Bamba, H.

1994-01-01

This paper reports experiments involving the handling of flexible parts (e.g. wires) when using a teleoperated system with time delay. The task is principally a peg-in-hole task involving the wrapping of a wire around two posts on the task-board. It is difficult to estimate the effects of the flexible parts; therefore, on-line teleoperation is indispensable for this class of unpredictable task. We first propose a teleoperation system based on the predictive image display, then describe an experimental teleoperation testbed with a four second transmission time delay. Finally, we report on wire handling operations that were performed to evaluate the performance of this system. Those experiments will contribute to future advanced experiments for the MITI ETS-7 mission.

COMPARISON OF LAPAROSCOPIC SKILLS PERFORMANCE USING SINGLE-SITE ACCESS (SSA) DEVICES VS. AN INDEPENDENT-PORT SSA APPROACH

PubMed Central

Schill, Matthew R.; Varela, J. Esteban; Frisella, Margaret M.; Brunt, L. Michael

2015-01-01

Background We compared performance of validated laparoscopic tasks on four commercially available single site access (SSA) access devices (AD) versus an independent port (IP) SSA set-up. Methods A prospective, randomized comparison of laparoscopic skills performance on four AD (GelPOINT™, SILS™ Port, SSL Access System™, TriPort™) and one IP SSA set-up was conducted. Eighteen medical students (2nd–4th year), four surgical residents, and five attending surgeons were trained to proficiency in multi-port laparoscopy using four laparoscopic drills (peg transfer, bean drop, pattern cutting, extracorporeal suturing) in a laparoscopic trainer box. Drills were then performed in random order on each IP-SSA and AD-SSA set-up using straight laparoscopic instruments. Repetitions were timed and errors recorded. Data are mean ± SD, and statistical analysis was by two-way ANOVA with Tukey HSD post-hoc tests. Results Attending surgeons had significantly faster total task times than residents or students (p< 0.001), but the difference between residents and students was NS. Pair-wise comparisons revealed significantly faster total task times for the IP-SSA set-up compared to all four AD-SSA’s within the student group only (p<0.05). Total task times for residents and attending surgeons showed a similar profile, but the differences were NS. When data for the three groups was combined, the total task time was less for the IP-SSA set-up than for each of the four AD-SSA set-ups (p < 0.001). Similarly,, the IP-SSA set-up was significantly faster than 3 of 4 AD-SSA set-ups for peg transfer, 3 of 4 for pattern cutting, and 2 of 4 for suturing. No significant differences in error rates between IP-SSA and AD-SSA set-ups were detected. Conclusions When compared to an IP-SSA laparoscopic set-up, single site access devices are associated with longer task performance times in a trainer box model, independent of level of training. Task performance was similar across different SSA devices. PMID:21993938

Cognitive Styles, Demographic Attributes, Task Performance and Affective Experiences: An Empirical Investigation into Astrophysics Data System (ADS) Core Users

NASA Astrophysics Data System (ADS)

Tong, Rong

As a primary digital library portal for astrophysics researchers, SAO/NASA ADS (Astrophysics Data System) 2.0 interface features several visualization tools such as Author Network and Metrics. This research study involves 20 ADS long term users who participated in a usability and eye tracking research session. Participants first completed a cognitive test, and then performed five tasks in ADS 2.0 where they explored its multiple visualization tools. Results show that over half of the participants were Imagers and half of the participants were Analytic. Cognitive styles were found to have significant impacts on several efficiency-based measures. Analytic-oriented participants were observed to spent shorter time on web pages and apps, made fewer web page changes than less-Analytic-driving participants in performing common tasks, whereas AI (Analytic-Imagery) participants also completed their five tasks faster than non-AI participants. Meanwhile, self-identified Imagery participants were found to be more efficient in their task completion through multiple measures including total time on task, number of mouse clicks, and number of query revisions made. Imagery scores were negatively associated with frequency of confusion and the observed counts of being surprised. Compared to those who did not claimed to be a visual person, self-identified Imagery participants were observed to have significantly less frequency in frustration and hesitation during their task performance. Both demographic variables and past user experiences were found to correlate with task performance; query revision also correlated with multiple time-based measurements. Considered as an indicator of efficiency, query revisions were found to correlate negatively with the rate of complete with ease, and positively with several time-based efficiency measures, rate of complete with some difficulty, and the frequency of frustration. These results provide rich insights into the cognitive styles of ADS' core users, the impact of such styles and demographic attributes on their task performance their affective and cognitive experiences, and their interaction behaviors while using the visualization component of ADS 2.0, and would subsequently contribute to the design of bibliographic retrieval systems for scientists.

Impact of novel shift handle laparoscopic tool on wrist ergonomics and task performance

PubMed Central

Yu, Denny; Lowndes, Bethany; Morrow, Missy; Kaufman, Kenton; Bingener, Juliane; Hallbeck, Susan

2015-01-01

Background Laparoscopic tool handles causing wrist flexion and extension more than 15° from neutral are considered “at-risk” for musculoskeletal strain. Therefore this study measured the impact of laparoscopic tool handle angles on wrist postures and task performance. Methods Eight surgeons performed standard and modified Fundamentals of Laparoscopic Surgery (FLS) tasks with laparoscopic tools. Tool A had three adjustable handle angle configurations, i.e., in-line 0° (A0), 30° (A30), and pistol-grip 70° (A70). Tool B was a fixed pistol-grip grasper. Participants performed FLS peg transfer, inverted peg transfer, and inverted circle-cut with each tool and handle angle. Inverted tasks were adapted from standard FLS tasks to simulate advanced tasks observed during abdominal wall surgeries, e.g., ventral hernia. Motion tracking, video-analysis, and modified NASA-TLX workload questionnaires were used to measure postures, performance (e.g., completion time and errors), and workload. Results Task performance did not differ among tools. For FLS peg transfer, self-reported physical workload was lower for B than A70, and mean wrist postures showed significantly higher flexion for in-line than pistol-grip tools (B and A70). For inverted peg transfer, workload was higher for all configurations. However, less time was spent in at-risk wrist postures for in-line (47%) than pistol-grip (93-94%), and most participants preferred Tool A. For inverted circle cut, workload did not vary across configurations, mean wrist posture was 10° closer to neutral for A0 than B, and median time in at-risk wrist postures was significantly less for A0 (43%) than B (87%). Conclusion The best ergonomic wrist positions for FLS (floor) tasks are provided by pistol-grip tools and for tasks on the abdominal wall (ventral surface) by in-line handles. Adjustable handle angle laparoscopic tools can reduce ergonomic risks for musculoskeletal strain and allow versatility for tasks alternating between the floor and ceiling positions in a surgical trainer without impacting performance. PMID:26541720

Impact of novel shift handle laparoscopic tool on wrist ergonomics and task performance.

PubMed

Yu, Denny; Lowndes, Bethany; Morrow, Missy; Kaufman, Kenton; Bingener, Juliane; Hallbeck, Susan

2016-08-01

Laparoscopic tool handles causing wrist flexion and extension more than 15° from neutral are considered "at risk" for musculoskeletal strain. Therefore, this study measured the impact of laparoscopic tool handle angles on wrist postures and task performance. Eight surgeons performed standard and modified Fundamentals of Laparoscopic Surgery (FLS) tasks with laparoscopic tools. Tool A had three adjustable handle angle configurations, i.e., in-line 0° (A0), 30° (A30), and pistol-grip 70° (A70). Tool B was a fixed pistol-grip grasper. Participants performed FLS peg transfer, inverted peg transfer, and inverted circle cut with each tool and handle angle. Inverted tasks were adapted from standard FLS tasks to simulate advanced tasks observed during abdominal wall surgeries, e.g., ventral hernia. Motion tracking, video analysis, and modified NASA-TLX workload questionnaires were used to measure postures, performance (e.g., completion time and errors), and workload. Task performance did not differ between tools. For FLS peg transfer, self-reported physical workload was lower for B than for A70, and mean wrist postures showed significantly higher flexion for in-line than for pistol-grip tools (B and A70). For inverted peg transfer, workload was higher for all configurations. However, less time was spent in at-risk wrist postures for in-line (47 %) than for pistol-grip (93-94 %), and most participants preferred Tool A. For inverted circle cut, workload did not vary across configurations, mean wrist posture was 10° closer to neutral for A0 than B, and median time in at-risk wrist postures was significantly less for A0 (43 %) than for B (87 %). The best ergonomic wrist positions for FLS (floor) tasks are provided by pistol-grip tools and for tasks on the abdominal wall (ventral surface) by in-line handles. Adjustable handle angle laparoscopic tools can reduce ergonomic risks of musculoskeletal strain and allow versatility for tasks alternating between the floor and ceiling positions in a surgical trainer without impacting performance.

Music experience influences laparoscopic skills performance.

PubMed

Boyd, Tanner; Jung, Inkyung; Van Sickle, Kent; Schwesinger, Wayne; Michalek, Joel; Bingener, Juliane

2008-01-01

Music education affects the mathematical and visuo-spatial skills of school-age children. Visuo-spatial abilities have a significant effect on laparoscopic suturing performance. We hypothesize that prior music experience influences the performance of laparoscopic suturing tasks. Thirty novices observed a laparoscopic suturing task video. Each performed 3 timed suturing task trials. Demographics were recorded. A repeated measures linear mixed model was used to examine the effects of prior music experience on suturing task time. Twelve women and 18 men completed the tasks. When adjusted for video game experience, participants who currently played an instrument performed significantly faster than those who did not (P<0.001). The model showed a significant sex by instrument interaction. Men who had never played an instrument or were currently playing an instrument performed better than women in the same group (P=0.002 and P<0.001). There was no sex difference in the performance of participants who had played an instrument in the past (P=0.29). This study attempted to investigate the effect of music experience on the laparoscopic suturing abilities of surgical novices. The visuo-spatial abilities used in laparoscopic suturing may be enhanced in those involved in playing an instrument.

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.

Motor learning from virtual reality to natural environments in individuals with Duchenne muscular dystrophy.

PubMed

Quadrado, Virgínia Helena; Silva, Talita Dias da; Favero, Francis Meire; Tonks, James; Massetti, Thais; Monteiro, Carlos Bandeira de Mello

2017-11-10

To examine whether performance improvements in the virtual environment generalize to the natural environment. we had 64 individuals, 32 of which were individuals with DMD and 32 were typically developing individuals. The groups practiced two coincidence timing tasks. In the more tangible button-press task, the individuals were required to 'intercept' a falling virtual object at the moment it reached the interception point by pressing a key on the computer. In the more abstract task, they were instructed to 'intercept' the virtual object by making a hand movement in a virtual environment using a webcam. For individuals with DMD, conducting a coincidence timing task in a virtual environment facilitated transfer to the real environment. However, we emphasize that a task practiced in a virtual environment should have higher rates of difficulties than a task practiced in a real environment. IMPLICATIONS FOR REHABILITATION Virtual environments can be used to promote improved performance in ?real-world? environments. Virtual environments offer the opportunity to create paradigms similar ?real-life? tasks, however task complexity and difficulty levels can be manipulated, graded and enhanced to increase likelihood of success in transfer of learning and performance. Individuals with DMD, in particular, showed immediate performance benefits after using virtual reality.

Three-dimensional vision enhances task performance independently of the surgical method.

PubMed

Wagner, O J; Hagen, M; Kurmann, A; Horgan, S; Candinas, D; Vorburger, S A

2012-10-01

Within the next few years, the medical industry will launch increasingly affordable three-dimensional (3D) vision systems for the operating room (OR). This study aimed to evaluate the effect of two-dimensional (2D) and 3D visualization on surgical skills and task performance. In this study, 34 individuals with varying laparoscopic experience (18 inexperienced individuals) performed three tasks to test spatial relationships, grasping and positioning, dexterity, precision, and hand-eye and hand-hand coordination. Each task was performed in 3D using binocular vision for open performance, the Viking 3Di Vision System for laparoscopic performance, and the DaVinci robotic system. The same tasks were repeated in 2D using an eye patch for monocular vision, conventional laparoscopy, and the DaVinci robotic system. Loss of 3D vision significantly increased the perceived difficulty of a task and the time required to perform it, independently of the approach (P < 0.0001-0.02). Simple tasks took 25 % to 30 % longer to complete and more complex tasks took 75 % longer with 2D than with 3D vision. Only the difficult task was performed faster with the robot than with laparoscopy (P = 0.005). In every case, 3D robotic performance was superior to conventional laparoscopy (2D) (P < 0.001-0.015). The more complex the task, the more 3D vision accelerates task completion compared with 2D vision. The gain in task performance is independent of the surgical method.

The Effects of Different Types of Environmental Noise on Academic Performance and Perceived Task Difficulty in Adolescents With ADHD.

PubMed

Batho, Lauren P; Martinussen, Rhonda; Wiener, Judith

2015-07-28

To examine the effects of environmental noises (speech and white noise) relative to a no noise control condition on the performance and difficulty ratings of youth with ADHD (N = 52) on academic tasks. Reading performance was measured by an oral retell (reading accuracy) and the time spent reading. Writing performance was measured through the proportion of correct writing sequences (writing accuracy) and the total words written on an essay. Participants in the white noise condition took less time to read the passage and wrote more words on the essay compared with participants in the other conditions, though white noise did not improve academic accuracy. The participants in the babble condition rated the tasks as most difficult. Although white noise appears to improve reading time and writing fluency, the findings suggest that white noise does not improve performance accuracy. Educational implications are discussed. © 2015 SAGE Publications.

Examining the relationship between endogenous pain modulation capacity and endurance exercise performance.

PubMed

Flood, Andrew; Waddington, Gordon; Cathcart, Stuart

2017-01-01

The aim of the current study was to examine the relationship between pain modulatory capacity and endurance exercise performance. Twenty-seven recreationally active males between 18 and 35 years of age participated in the study. Pain modulation was assessed by examining the inhibitory effect of a noxious conditioning stimulus (cuff occlusion) on the perceived intensity of a second noxious stimulus (pressure pain threshold). Participants completed two, maximal voluntary contractions followed by a submaximal endurance time task. Both performance tasks involved an isometric contraction of the non-dominant leg. The main analysis uncovered a correlation between pain modulatory capacity and performance on the endurance time task (r = -.425, p = .027), such that those with elevated pain modulation produced longer endurance times. These findings are the first to demonstrate the relationship between pain modulation responses and endurance exercise performance.

Impact of 2D and 3D vision on performance of novice subjects using da Vinci robotic system.

PubMed

Blavier, A; Gaudissart, Q; Cadière, G B; Nyssen, A S

2006-01-01

The aim of this study was to evaluate the impact of 3D and 2D vision on performance of novice subjects using da Vinci robotic system. 224 nurses without any surgical experience were divided into two groups and executed a motor task with the robotic system in 2D for one group and with the robotic system in 3D for the other group. Time to perform the task was recorded. Our data showed significant better time performance in 3D view (24.67 +/- 11.2) than in 2D view (40.26 +/- 17.49, P < 0.001). Our findings emphasized the advantage of 3D vision over 2D view in performing surgical task, encouraging the development of efficient and less expensive 3D systems in order to improve the accuracy of surgical gesture, the resident training and the operating time.

Obesity-specific neural cost of maintaining gait performance under complex conditions in community-dwelling older adults.

PubMed

Osofundiya, Olufunmilola; Benden, Mark E; Dowdy, Diane; Mehta, Ranjana K

2016-06-01

Recent evidence of obesity-related changes in the prefrontal cortex during cognitive and seated motor activities has surfaced; however, the impact of obesity on neural activity during ambulation remains unclear. The purpose of this study was to determine obesity-specific neural cost of simple and complex ambulation in older adults. Twenty non-obese and obese individuals, 65years and older, performed three tasks varying in the types of complexity of ambulation (simple walking, walking+cognitive dual-task, and precision walking). Maximum oxygenated hemoglobin, a measure of neural activity, was measured bilaterally using a portable functional near infrared spectroscopy system, and gait speed and performance on the complex tasks were also obtained. Complex ambulatory tasks were associated with ~2-3.5 times greater cerebral oxygenation levels and ~30-40% slower gait speeds when compared to the simple walking task. Additionally, obesity was associated with three times greater oxygenation levels, particularly during the precision gait task, despite obese adults demonstrating similar gait speeds and performances on the complex gait tasks as non-obese adults. Compared to existing studies that focus solely on biomechanical outcomes, the present study is one of the first to examine obesity-related differences in neural activity during ambulation in older adults. In order to maintain gait performance, obesity was associated with higher neural costs, and this was augmented during ambulatory tasks requiring greater precision control. These preliminary findings have clinical implications in identifying individuals who are at greater risk of mobility limitations, particularly when performing complex ambulatory tasks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of time span and task load on pilot mental workload

NASA Technical Reports Server (NTRS)

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

1986-01-01

Two sets of simulations designed to examine how a pilot's mental workload is affected by continuous manual-control activity versus discrete mental tasks that included the length of time between receiving an assignment and executing it are described. The first experiment evaluated two types of measures: objective performance indicators and subjective ratings. Subjective ratings for the two missions were different, but the objective performance measures were similar. In the second experiments, workload levels were increased and a second performance measure was taken. Mental workload had no influence on either performance-based workload measure. Subjective ratings discriminated among the scenarios and correlated with performance measures for high-workload flights. The number of mental tasks performed did not influence error rates, although high manual workloads did increase errors.

Cognitive performance and BMI in childhood: Shared genetic influences between reaction time but not response inhibition

USDA-ARS?s Scientific Manuscript database

The aim of this work is to understand whether shared genetic influences can explain the associationbetween obesity and cognitive performance, including slower and more variable reaction times(RTs) and worse response inhibition. RT on a four-choice RT task and the go/no-go task, and commission errors...

Levels of Information Processing in a Fitts law task (LIPFitts)

NASA Technical Reports Server (NTRS)

Mosier, K. L.; Hart, S. G.

1986-01-01

State-of-the-art flight technology has restructured the task of human operators, decreasing the need for physical and sensory resources, and increasing the quantity of cognitive effort required, changing it qualitatively. Recent technological advances have the most potential for impacting a pilot in two areas: performance and mental workload. In an environment in which timing is critical, additional cognitive processing can cause performance decrements, and increase a pilot's perception of the mental workload involved. The effects of stimulus processing demands on motor response performance and subjective mental workload are examined, using different combinations of response selection and target acquisition tasks. The information processing demands of the response selection were varied (e.g., Sternberg memory set tasks, math equations, pattern matching), as was the difficulty of the response execution. Response latency as well as subjective workload ratings varied in accordance with the cognitive complexity of the task. Movement times varied according to the difficulty of the response execution task. Implications in terms of real-world flight situations are discussed.

Acute effects of caffeine on several operant behaviors in rhesus monkeys.

PubMed

Buffalo, E A; Gillam, M P; Allen, R R; Paule, M G

1993-11-01

The acute effects of 1,3-trimethylxanthine (caffeine) were assessed using an operant test battery (OTB) of complex food-reinforced tasks that are thought to depend upon relatively specific brain functions, such as motivation to work for food (progressive ratio, PR), learning (incremental repeated acquisition, IRA), color and position discrimination (conditioned position responding, CPR), time estimation (temporal response differentiation, TRD), and short-term memory and attention (delayed matching-to-sample, DMTS). Endpoints included response rates (RR), accuracies (ACC), and percent task completed (PTC). Caffeine sulfate (0.175-20.0 mg/kg, IV), given 15 min pretesting, produced significant dose-dependent decreases in TRD percent task completed and accuracy at doses > or = 5.6 mg/kg. Caffeine produced no systematic effects on either DMTS or PR responding, but low doses tended to enhance performance in both IRA and CPR tasks. Thus, in monkeys, performance of an operant task designed to model time estimation is more sensitive to the disruptive effects of caffeine than is performance of the other tasks in the OTB.

Perceived control in rhesus monkeys (Macaca mulatta) - Enhanced video-task performance

NASA Technical Reports Server (NTRS)

Washburn, David A.; Hopkins, William D.; Rumbaugh, Duane M.

1991-01-01

This investigation was designed to determine whether perceived control effects found in humans extend to rhesus monkeys (Macaca mulatta) tested in a video-task format, using a computer-generated menu program, SELECT. Choosing one of the options in SELECT resulted in presentation of five trials of a corresponding task and subsequent return to the menu. In Experiments 1-3, the animals exhibited stable, meaningful response patterns in this task (i.e., they made choices). In Experiment 4, performance on tasks that were selected by the animals significantly exceeded performance on identical tasks when assigned by the experimenter under comparable conditions (e.g., time of day, order, variety). The reliable and significant advantage for performance on selected tasks, typically found in humans, suggests that rhesus monkeys were able to perceive the availability of choices.

Experimental system for measurement of radiologists' performance by visual search task.

PubMed

Maeda, Eriko; Yoshikawa, Takeharu; Nakashima, Ryoichi; Kobayashi, Kazufumi; Yokosawa, Kazuhiko; Hayashi, Naoto; Masutani, Yoshitaka; Yoshioka, Naoki; Akahane, Masaaki; Ohtomo, Kuni

2013-01-01

Detective performance of radiologists for "obvious" targets should be evaluated by visual search task instead of ROC analysis, but visual task have not been applied to radiology studies. The aim of this study was to set up an environment that allows visual search task in radiology, to evaluate its feasibility, and to preliminarily investigate the effect of career on the performance. In a darkroom, ten radiologists were asked to answer the type of lesion by pressing buttons, when images without lesions, with bulla, ground-glass nodule, and solid nodule were randomly presented on a display. Differences in accuracy and reaction times depending on board certification were investigated. The visual search task was successfully and feasibly performed. Radiologists were found to have high sensitivity, specificity, positive predictive values and negative predictive values in non-board and board groups. Reaction time was under 1 second for all target types in both groups. Board radiologists were significantly faster in answering for bulla, but there were no significant differences for other targets and values. We developed an experimental system that allows visual search experiment in radiology. Reaction time for detection of bulla was shortened with experience.

Neuroticism related differences in the functional neuroanatomical correlates of multitasking. An fMRI study.

PubMed

Szameitat, Andre J; Saylik, Rahmi; Parton, Andrew

2016-12-02

It is known that neuroticism impairs cognitive performance mostly in difficult tasks, but not so much in easier tasks. One pervasive situation of this type is multitasking, in which the combination of two simple tasks creates a highly demanding dual-task, and consequently high neurotics show higher dual-task costs than low neurotics. However, the functional neuroanatomical correlates of these additional performance impairments in high neurotics are unknown. To test for this, we assessed brain activity by means of functional magnetic resonance imaging (fMRI) in 17 low and 15 high neurotics while they were performing a demanding dual-task and the less demanding component tasks as single-tasks. Behavioural results showed that performance (response times and error rates) was lower in the dual-task than in the single-tasks (dual-task costs), and that these dual-task costs were significantly higher in high neurotics. Imaging data showed that high neurotics showed less dual-task specific activation in lateral (mainly middle frontal gyrus) and medial prefrontal cortices. We conclude that high levels of neuroticism impair behavioural performance in demanding tasks, and that this impairment is accompanied by reduced activation of the task-associated brain areas. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Participant Withdrawal as a Function of Hedonic Value of Task and Time of Semester

ERIC Educational Resources Information Center

Bellone, John A.; Navarick, Douglas J.; Mendoza, Raquel

2012-01-01

Undergraduates participating in experiments late in the semester generally perform more poorly on demanding tasks and withdraw more often than those participating early. To investigate effects of task aversiveness, some participants were instructed to choose brief cartoon reinforcement with a long time-out while others were instructed to choose…

A model for combined targeting and tracking tasks in computer applications.

PubMed

Senanayake, Ransalu; Hoffmann, Errol R; Goonetilleke, Ravindra S

2013-11-01

Current models for targeted-tracking are discussed and shown to be inadequate as a means of understanding the combined task of tracking, as in the Drury's paradigm, and having a final target to be aimed at, as in the Fitts' paradigm. It is shown that the task has to be split into components that are, in general, performed sequentially and have a movement time component dependent on the difficulty of the individual component of the task. In some cases, the task time may be controlled by the Fitts' task difficulty, and in others, it may be dominated by the Drury's task difficulty. Based on an experiment carried out that captured movement time in combinations of visually controlled and ballistic movements, a model for movement time in targeted-tracking was developed.

Age and measurement time-of-day effects on speech recognition in noise.

PubMed

Veneman, Carrie E; Gordon-Salant, Sandra; Matthews, Lois J; Dubno, Judy R

2013-01-01

The purpose of this study was to determine the effect of measurement time of day on speech recognition in noise and the extent to which time-of-day effects differ with age. Older adults tend to have more difficulty understanding speech in noise than younger adults, even when hearing is normal. Two possible contributors to this age difference in speech recognition may be measurement time of day and inhibition. Most younger adults are "evening-type," showing peak circadian arousal in the evening, whereas most older adults are "morning-type," with circadian arousal peaking in the morning. Tasks that require inhibition of irrelevant information have been shown to be affected by measurement time of day, with maximum performance attained at one's peak time of day. The authors hypothesized that a change in inhibition will be associated with measurement time of day and therefore affect speech recognition in noise, with better performance in the morning for older adults and in the evening for younger adults. Fifteen younger evening-type adults (20-28 years) and 15 older morning-type adults with normal hearing (66-78 years) listened to the Hearing in Noise Test (HINT) and the Quick Speech in Noise (QuickSIN) test in the morning and evening (peak and off-peak times). Time of day preference was assessed using the Morningness-Eveningness Questionnaire. Sentences and noise were presented binaurally through insert earphones. During morning and evening sessions, participants solved word-association problems within the visual-distraction task (VDT), which was used as an estimate of inhibition. After each session, participants rated perceived mental demand of the tasks using a revised version of the NASA Task Load Index. Younger adults performed significantly better on the speech-in-noise tasks and rated themselves as requiring significantly less mental demand when tested at their peak (evening) than off-peak (morning) time of day. In contrast, time-of-day effects were not observed for the older adults on the speech recognition or rating tasks. Although older adults required significantly more advantageous signal-to-noise ratios than younger adults for equivalent speech-recognition performance, a significantly larger younger versus older age difference in speech recognition was observed in the evening than in the morning. Older adults performed significantly poorer than younger adults on the VDT, but performance was not affected by measurement time of day. VDT performance for misleading distracter items was significantly correlated with HINT and QuickSIN test performance at the peak measurement time of day. Although all participants had normal hearing, speech recognition in noise was significantly poorer for older than younger adults, with larger age-related differences in the evening (an off-peak time for older adults) than in the morning. The significant effect of measurement time of day suggests that this factor may impact the clinical assessment of speech recognition in noise for all individuals. It appears that inhibition, as estimated by a visual distraction task for misleading visual items, is a cognitive mechanism that is related to speech-recognition performance in noise, at least at a listener's peak time of day.

Sustained attention in adult ADHD: time-on-task effects of various measures of attention.

PubMed

Tucha, Lara; Fuermaier, Anselm B M; Koerts, Janneke; Buggenthin, Rieka; Aschenbrenner, Steffen; Weisbrod, Matthias; Thome, Johannes; Lange, Klaus W; Tucha, Oliver

2017-02-01

Neuropsychological research on adults with ADHD showed deficits in various aspects of attention. However, the majority of studies failed to explore the change of performance over time, so-called time-on-task effects. As a consequence, little is known about sustained attention performance of adults with ADHD. The aim of the present study was therefore to test the hypothesis of sustained attention deficits of adults with ADHD. Twenty-nine adults with ADHD and 30 healthy individuals were assessed on four 20-min tests of sustained attention, measuring alertness, selective attention, divided attention and flexibility. The deterioration of performance over time (time-on-task effects) was compared between patients with ADHD and healthy individuals to conclude on sustained attention performance. Compared to healthy individuals, patients with ADHD showed significant deficits of medium size in selective attention and divided attention. Furthermore, medium sustained attention deficits was observed in measures of alertness, selective attention and divided attention. This study supports the notion of sustained attention deficits of adults with ADHD.

Time savings--realized and potential--and fair compensation for community health workers in Kenyan health facilities: a mixed-methods approach.

PubMed

Sander, Laura D; Holtzman, David; Pauly, Mark; Cohn, Jennifer

2015-01-30

Sub-Saharan Africa faces a severe health worker shortage, which community health workers (CHWs) may fill. This study describes tasks shifted from clinicians to CHWs in Kenya, places monetary valuations on CHWs' efforts, and models effects of further task shifting on time demands of clinicians and CHWs. Mixed methods were used for this study. Interviews were conducted with 28 CHWs and 19 clinicians in 17 health facilities throughout Kenya focusing on task shifting involving CHWs, time savings for clinicians as a result of task shifting, barriers and enabling factors to CHWs' work, and appropriate CHW compensation. Twenty CHWs completed task diaries over a 14-day period to examine current CHW tasks and the amount of time spent performing them. A modeling exercise was conducted examining a current task-shifting example and another scenario in which additional task shifting to CHWs has occurred. CHWs worked an average of 5.3 hours per day and spent 36% of their time performing tasks shifted from clinicians. We estimated a monthly valuation of US$ 117 per CHW. The modeling exercise demonstrated that further task shifting would reduce the number of clinicians needed while maintaining clinic productivity by significantly increasing the number of CHWs. CHWs are an important component of healthcare delivery in Kenya. Our monetary estimates of current CHW contributions provide starting points for further discussion, research and planning regarding CHW compensation and programs. Additional task shifting to CHWs may further offload overworked clinicians while maintaining overall productivity.

Mental fatigue and impaired response processes: event-related brain potentials in a Go/NoGo task.

PubMed

Kato, Yuichiro; Endo, Hiroshi; Kizuka, Tomohiro

2009-05-01

The effects of mental fatigue on the availability of cognitive resources and associated response-related processes were examined using event-related brain potentials. Subjects performed a Go/NoGo task for 60 min. Reaction time, number of errors, and mental fatigue scores all significantly increased with time spent on the task. The NoGo-P3 amplitude significantly decreased with time on task, but the Go-P3 amplitude was not modulated. The amplitude of error-related negativity (Ne/ERN) also decreased with time on task. These results indicate that mental fatigue attenuates resource allocation and error monitoring for NoGo stimuli. The Go- and NoGo-P3 latencies both increased with time on task, indicative of a delay in stimulus evaluation time due to mental fatigue. NoGo-N2 latency increased with time on task, but NoGo-N2 amplitude was not modulated. The amplitude of response-locked lateralized readiness potential (LRP) significantly decreased with time on task. Mental fatigue appears to slows down the time course of response inhibition, and impairs the intensity of response execution.

Total sleep deprivation does not significantly degrade semantic encoding.

PubMed

Honn, K A; Grant, D A; Hinson, J M; Whitney, P; Van Dongen, Hpa

2018-01-17

Sleep deprivation impairs performance on cognitive tasks, but it is unclear which cognitive processes it degrades. We administered a semantic matching task with variable stimulus onset asynchrony (SOA) and both speeded and self-paced trial blocks. The task was administered at the baseline and 24 hours later after 30.8 hours of total sleep deprivation (TSD) or matching well-rested control. After sleep deprivation, the 20% slowest response times (RTs) were significantly increased. However, the semantic encoding time component of the RTs remained at baseline level. Thus, the performance impairment induced by sleep deprivation on this task occurred in cognitive processes downstream of semantic encoding.

Evaluation of the Display of Cognitive State Feedback to Drive Adaptive Task Sharing

PubMed Central

Dorneich, Michael C.; Passinger, Břetislav; Hamblin, Christopher; Keinrath, Claudia; Vašek, Jiři; Whitlow, Stephen D.; Beekhuyzen, Martijn

2017-01-01

This paper presents an adaptive system intended to address workload imbalances between pilots in future flight decks. Team performance can be maximized when task demands are balanced within crew capabilities and resources. Good communication skills enable teams to adapt to changes in workload, and include the balancing of workload between team members This work addresses human factors priorities in the aviation domain with the goal to develop concepts that balance operator workload, support future operator roles and responsibilities, and support new task requirements, while allowing operators to focus on the most safety critical tasks. A traditional closed-loop adaptive system includes the decision logic to turn automated adaptations on and off. This work takes a novel approach of replacing the decision logic, normally performed by the automation, with human decisions. The Crew Workload Manager (CWLM) was developed to objectively display the workload between pilots and recommend task sharing; it is then the pilots who “close the loop” by deciding how to best mitigate unbalanced workload. The workload was manipulated by the Shared Aviation Task Battery (SAT-B), which was developed to provide opportunities for pilots to mitigate imbalances in workload between crew members. Participants were put in situations of high and low workload (i.e., workload was manipulated as opposed to being measured), the workload was then displayed to pilots, and pilots were allowed to decide how to mitigate the situation. An evaluation was performed that utilized the SAT-B to manipulate workload and create workload imbalances. Overall, the CWLM reduced the time spent in unbalanced workload and improved the crew coordination in task sharing while not negatively impacting concurrent task performance. Balancing workload has the potential to improve crew resource management and task performance over time, and reduce errors and fatigue. Paired with a real-time workload measurement system, the CWLM could help teams manage their own task load distribution. PMID:28400716

Evaluation of the Display of Cognitive State Feedback to Drive Adaptive Task Sharing.

PubMed

Dorneich, Michael C; Passinger, Břetislav; Hamblin, Christopher; Keinrath, Claudia; Vašek, Jiři; Whitlow, Stephen D; Beekhuyzen, Martijn

2017-01-01

This paper presents an adaptive system intended to address workload imbalances between pilots in future flight decks. Team performance can be maximized when task demands are balanced within crew capabilities and resources. Good communication skills enable teams to adapt to changes in workload, and include the balancing of workload between team members This work addresses human factors priorities in the aviation domain with the goal to develop concepts that balance operator workload, support future operator roles and responsibilities, and support new task requirements, while allowing operators to focus on the most safety critical tasks. A traditional closed-loop adaptive system includes the decision logic to turn automated adaptations on and off. This work takes a novel approach of replacing the decision logic, normally performed by the automation, with human decisions. The Crew Workload Manager (CWLM) was developed to objectively display the workload between pilots and recommend task sharing; it is then the pilots who "close the loop" by deciding how to best mitigate unbalanced workload. The workload was manipulated by the Shared Aviation Task Battery (SAT-B), which was developed to provide opportunities for pilots to mitigate imbalances in workload between crew members. Participants were put in situations of high and low workload (i.e., workload was manipulated as opposed to being measured), the workload was then displayed to pilots, and pilots were allowed to decide how to mitigate the situation. An evaluation was performed that utilized the SAT-B to manipulate workload and create workload imbalances. Overall, the CWLM reduced the time spent in unbalanced workload and improved the crew coordination in task sharing while not negatively impacting concurrent task performance. Balancing workload has the potential to improve crew resource management and task performance over time, and reduce errors and fatigue. Paired with a real-time workload measurement system, the CWLM could help teams manage their own task load distribution.

Associations between physical function, dual-task performance and cognition in patients with mild Alzheimer's disease.

PubMed

Sobol, Nanna Aue; Hoffmann, Kristine; Vogel, Asmus; Lolk, Annette; Gottrup, Hanne; Høgh, Peter; Hasselbalch, Steen G; Beyer, Nina

2016-11-01

Alzheimer's disease (AD) causes a gradual decline in cognition, limitations of dual-tasking and physical function leading to total dependence. Hence, information about the interaction between physical function, dual-task performance and cognition may lead to new treatment strategies with the purpose of preserving function and quality of life. The objective of this study was to investigate the associations between physical function, dual-task performance and cognition in community-dwelling patients with mild AD. Baseline results from 185 participants (50-90 years old) in the single blinded multicenter RCT 'ADEX' (Alzheimer's disease: the effect of physical exercise) were used. Assessments included tests of physical function: 400-m walk test, 10-m walk test, Timed Up and Go test and 30-s chair stand test; dual-task performance, i.e., 10-m walk while counting backwards from 50 or naming the months backwards; and cognition, i.e., Mini Mental State Examination, Symbol Digit Modalities Test, the Stroop Color and Word Test, and Lexical verbal fluency test. Results in the 30-s chair stand test correlated significantly with all tests of cognition (r = .208-.242) while the other physical function tests only randomly correlated with tests of cognition. Results in the dual-task counting backwards correlated significantly with results in all tests of cognition (r = .259-.388), which accounted for 7%-15% of the variation indicating that a faster time to complete dual-task performance was associated with better cognitive performance. The evidence of the associations between physical function, dual-task performance and cognition is important when creating new rehabilitation interventions to patients with mild AD.

ADHD performance reflects inefficient but not impulsive information processing: a diffusion model analysis.

PubMed

Metin, Baris; Roeyers, Herbert; Wiersema, Jan R; van der Meere, Jaap J; Thompson, Margaret; Sonuga-Barke, Edmund

2013-03-01

Attention-deficit/hyperactivity disorder (ADHD) is associated with performance deficits across a broad range of tasks. Although individual tasks are designed to tap specific cognitive functions (e.g., memory, inhibition, planning, etc.), these deficits could also reflect general effects related to either inefficient or impulsive information processing or both. These two components cannot be isolated from each other on the basis of classical analysis in which mean reaction time (RT) and mean accuracy are handled separately. Seventy children with a diagnosis of combined type ADHD and 50 healthy controls (between 6 and 17 years) performed two tasks: a simple two-choice RT (2-CRT) task and a conflict control task (CCT) that required higher levels of executive control. RT and errors were analyzed using the Ratcliff diffusion model, which divides decisional time into separate estimates of information processing efficiency (called "drift rate") and speed-accuracy tradeoff (SATO, called "boundary"). The model also provides an estimate of general nondecisional time. Results were the same for both tasks independent of executive load. ADHD was associated with lower drift rate and less nondecisional time. The groups did not differ in terms of boundary parameter estimates. RT and accuracy performance in ADHD appears to reflect inefficient rather than impulsive information processing, an effect independent of executive function load. The results are consistent with models in which basic information processing deficits make an important contribution to the ADHD cognitive phenotype. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Changing behavior and accuracy with time on task in mammography screening

NASA Astrophysics Data System (ADS)

Taylor-Phillips, Sian; Jenkinson, David; Stinton, Chris; Wallis, Matthew G.; Clarke, Aileen

2017-03-01

Background: The vigilance decrement and prevalence effect both describe changes to speed and accuracy with time on task. Whilst there is much laboratory based research on these effects, little is known about whether they occur in real world mammography practice. Methods: The Changing Case Order to Optimise Patterns of Performance in Screening (CO-OPS) trial randomised 37,724 batches containing 1.2 million women attending breast screening to intervention or control (222,208 from the Midlands of England). In the control arm the batch was examined in the same order by both readers, in the intervention arm it was examined in a different order by both readers. Time taken, recall decision by both readers, and cancers detected were recorded for each case, and used to examine patterns of performance with time on task. Results: 49,575 women were recalled and 10,484 had cancer detected. Median time taken to examine each case was 35 seconds (out of cases where time taken was 10 minutes or less). The intervention did not affect overall cancer detection rates or recall rates. A more detailed analysis of the Midlands data indicates cancer detection rate did not change when reading up to 60 cases in a batch, but recall rate reduced. Time taken per case reduced with time on task, from a median 41 seconds when examining the second case in the batch to 28.5 seconds examining the 60th case. Conclusion: Reader behavior and performance systematically changes with time on task in breast screening.

A comparison of the effects of a secondary task and lorazepam on cognitive performance.

PubMed

File, S E

1992-01-01

In order to test whether the lorazepam-induced impairments in a variety of cognitive tasks were similar to those of divided attention, the effects of lorazepam (2.5 mg) in healthy volunteers were compared with those requiring subjects to perform an additional task (detecting silences superimposed onto classical music). Neither treatment impaired implicit memory or judgements of frequency. Both treatments impaired performance in tests of speed, lorazepam having the greatest effect on number cancellation and the additional task having the greatest effect on simple reaction time. Both treatments impaired performance in a coding task, in a test of explicit episodic memory and in judgements of recency (indicating impaired coding of contextual information). Lorazepam significantly reduced performance in a word completion task, but this was unimpaired in the group performing the additional task. In general, the pattern of results suggests that there are similarities between the effects of divided attention and lorazepam treatment, and that lorazepam-induced cognitive impairments are not restricted to explicit tests of episodic memory.

Procedural learning: A developmental study of motor sequence learning and probabilistic classification learning in school-aged children.

PubMed

Mayor-Dubois, Claire; Zesiger, Pascal; Van der Linden, Martial; Roulet-Perez, Eliane

2016-01-01

In this study, we investigated motor and cognitive procedural learning in typically developing children aged 8-12 years with a serial reaction time (SRT) task and a probabilistic classification learning (PCL) task. The aims were to replicate and extend the results of previous SRT studies, to investigate PCL in school-aged children, to explore the contribution of declarative knowledge to SRT and PCL performance, to explore the strategies used by children in the PCL task via a mathematical model, and to see whether performances obtained in motor and cognitive tasks correlated. The results showed similar learning effects in the three age groups in the SRT and in the first half of the PCL tasks. Participants did not develop explicit knowledge in the SRT task whereas declarative knowledge of the cue-outcome associations correlated with the performances in the second half of the PCL task, suggesting a participation of explicit knowledge after some time of exposure in PCL. An increasing proportion of the optimal strategy use with increasing age was observed in the PCL task. Finally, no correlation appeared between cognitive and motor performance. In conclusion, we extended the hypothesis of age invariance from motor to cognitive procedural learning, which had not been done previously. The ability to adopt more efficient learning strategies with age may rely on the maturation of the fronto-striatal loops. The lack of correlation between performance in the SRT task and the first part of the PCL task suggests dissociable developmental trajectories within the procedural memory system.

[Developmental changes of rapid automatized naming and Hiragana reading of Japanese in elementary-school children].

PubMed

Kobayashi, Tomoka; Inagaki, Masumi; Gunji, Atsuko; Yatabe, Kiyomi; Kita, Yosuke; Kaga, Makiko; Gotoh, Takaaki; Koike, Toshihide

2011-11-01

Two hundred and seven Japanese elementary school children aged from 6 (Grade 1) to 12 (Grade 6) years old were tested for their abilities to name numbers and pictured objects along with reading Hiragana characters and words. These children all showed typical development and their classroom teachers judged that they were not having any problems with reading or writing. The children were randomly divided into two groups, the first group was assigned to two naming tasks;the rapid automatized naming (RAN) of "numbers" and "pictured objects," the second group was assigned to two rapid alternative stimulus (RAS) naming tasks using numbers and pictured objects. All children were asked to perform two reading tasks that were written in Hiragana script: single mora reading task and four syllable word reading task. The total articulation time for naming and reading and performance in terms of accuracy were measured for each task. Developmental changes in these variables were evaluated. The articulation time was significantly longer for the first graders, and it gradually shortened as they moved through to the upper grades in all tasks. The articulation time reached a plateau in the 5th grade for the number naming, while gradual change continued after drastic change in the lower grades for the pictured object naming. The articulation times for the single mora reading and RAN of numbers correlated strongly. The articulation time for the RAS naming was significantly longer compared to that for the RAN, though there were very few errors. The RAS naming showed the highest correlation with the four syllable word reading. This study demonstrated that the performance in rapid automatized naming of numbers and pictures were closely related with performance on reading tasks. Thus Japanese children with reading disorders such as developmental dyslexia should also be evaluated for rapid automatized naming.

Cerebellar tDCS Does Not Enhance Performance in an Implicit Categorization Learning Task.

PubMed

Verhage, Marie C; Avila, Eric O; Frens, Maarten A; Donchin, Opher; van der Geest, Jos N

2017-01-01

Background: Transcranial Direct Current Stimulation (tDCS) is a form of non-invasive electrical stimulation that changes neuronal excitability in a polarity and site-specific manner. In cognitive tasks related to prefrontal and cerebellar learning, cortical tDCS arguably facilitates learning, but the few studies investigating cerebellar tDCS, however, are inconsistent. Objective: We investigate the effect of cerebellar tDCS on performance of an implicit categorization learning task. Methods: Forty participants performed a computerized version of an implicit categorization learning task where squares had to be sorted into two categories, according to an unknown but fixed rule that integrated both the size and luminance of the square. Participants did one round of categorization to familiarize themselves with the task and to provide a baseline of performance. After that, 20 participants received anodal tDCS (20 min, 1.5 mA) over the right cerebellum, and 19 participants received sham stimulation and simultaneously started a second session of the categorization task using a new rule. Results: As expected, subjects performed better in the second session than in the first, baseline session, showing increased accuracy scores and reduced reaction times. Over trials, participants learned the categorization rule, improving their accuracy and reaction times. However, we observed no effect of anodal tDCS stimulation on overall performance or on learning, compared to sham stimulation. Conclusion: These results suggest that cerebellar tDCS does not modulate performance and learning on an implicit categorization task.

Measuring Attention in Rodents: Comparison of a Modified Signal Detection Task and the 5-Choice Serial Reaction Time Task

PubMed Central

Turner, Karly M.; Peak, James; Burne, Thomas H. J.

2016-01-01

Neuropsychiatric research has utilized cognitive testing in rodents to improve our understanding of cognitive deficits and for preclinical drug development. However, more sophisticated cognitive tasks have not been as widely exploited due to low throughput and the extensive training time required. We developed a modified signal detection task (SDT) based on the growing body of literature aimed at improving cognitive testing in rodents. This study directly compares performance on the modified SDT with a traditional test for measuring attention, the 5-choice serial reaction time task (5CSRTT). Adult male Sprague-Dawley rats were trained on either the 5CSRTT or the SDT. Briefly, the 5CSRTT required rodents to pay attention to a spatial array of five apertures and respond with a nose poke when an aperture was illuminated. The SDT required the rat to attend to a light panel and respond either left or right to indicate the presence of a signal. In addition, modifications were made to the reward delivery, timing, control of body positioning, and the self-initiation of trials. It was found that less training time was required for the SDT, with both sessions to criteria and daily session duration significantly reduced. Rats performed with a high level of accuracy (>87%) on both tasks, however omissions were far more frequent on the 5CSRTT. The signal duration was reduced on both tasks as a manipulation of task difficulty relevant to attention and a similar pattern of decreasing accuracy was observed on both tasks. These results demonstrate some of the advantages of the SDT over the traditional 5CSRTT as being higher throughput with reduced training time, fewer omission responses and their body position was controlled at stimulus onset. In addition, rats performing the SDT had comparable high levels of accuracy. These results highlight the differences and similarities between the 5CSRTT and a modified SDT as tools for assessing attention in preclinical animal models. PMID:26834597

Mind-wandering, cognition, and performance: a theory-driven meta-analysis of attention regulation.

PubMed

Randall, Jason G; Oswald, Frederick L; Beier, Margaret E

2014-11-01

The current meta-analysis accumulates empirical findings on the phenomenon of mind-wandering, integrating and interpreting findings in light of psychological theories of cognitive resource allocation. Cognitive resource theory emphasizes both individual differences in attentional resources and task demands together to predict variance in task performance. This theory motivated our conceptual and meta-analysis framework by introducing moderators indicative of task-demand to predict who is more likely to mind-wander under what conditions, and to predict when mind-wandering and task-related thought are more (or less) predictive of task performance. Predictions were tested via a random-effects meta-analysis of correlations obtained from normal adult samples (k = 88) based on measurement of specified episodes of off-task and/or on-task thought frequency and task performance. Results demonstrated that people with fewer cognitive resources tend to engage in more mind-wandering, whereas those with more cognitive resources are more likely to engage in task-related thought. Addressing predictions of resource theory, we found that greater time-on-task-although not greater task complexity-tended to strengthen the negative relation between cognitive resources and mind-wandering. Additionally, increases in mind-wandering were generally associated with decreases in task performance, whereas increases in task-related thought were associated with increased performance. Further supporting resource theory, the negative relation between mind-wandering and performance was more pronounced for more complex tasks, though not longer tasks. Complementarily, the positive association between task-related thought and performance was stronger for more complex tasks and for longer tasks. We conclude by discussing implications and future research directions for mind-wandering as a construct of interest in psychological research. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

How "fun/importance" fit affects performance: relating implicit theories to instructions.

PubMed

Bianco, Amy T; Higgins, E Tory; Klem, Adena

2003-09-01

People experience a regulatory fit when they employ means of goal pursuit that fit their regulatory orientation, and this fit increases motivation that can enhance performance. The present studies extend previous research on regulatory fit to the classic motivational variables of fun and importance. They also examine for the first time the effect on performance of the fit between individuals' implicit theories about a task's fun or importance and their strategic engagement of the task as fun or important as induced by task instructions. In all three studies, task performance was better when the external task instructions "fit" rather than did not fit participants' implicit theory for the task. The implications of these findings for understanding the motivational effects of fun and importance are discussed.

Evaluation of induced and evoked changes in EEG during selective attention to verbal stimuli.

PubMed

Horki, P; Bauernfeind, G; Schippinger, W; Pichler, G; Müller-Putz, G R

2016-09-01

Two challenges need to be addressed before bringing non-motor mental tasks for brain-computer interface (BCI) control to persons in a minimally conscious state (MCS), who can be behaviorally unresponsive even when proven to be consciously aware: first, keeping the cognitive demands as low as possible so that they could be fulfilled by persons with MCS. Second, increasing the control of experimental protocol (i.e. type and timing of the task performance). The goal of this study is twofold: first goal is to develop an experimental paradigm that can facilitate the performance of brain-teasers (e.g. mental subtraction and word generation) on the one hand, and can increase the control of experimental protocol on the other hand. The second goal of this study is to exploit the similar findings for mentally attending to someone else's verbal performance of brain-teaser tasks and self-performing the same tasks to setup an online BCI, and to compare it in healthy participants to the current "state-of-the-art" motor imagery (MI, sports). The response accuracies for the best performing healthy participants indicate that selective attention to verbal performance of mental subtraction (SUB) is a viable alternative to the MI. Time-frequency analysis of the SUB task in one participant with MCS did not reveal any significant (p<0.05) EEG changes, whereas imagined performance of one sport of participants' choice (SPORT) revealed task-related EEG changes over neurophysiological plausible cortical areas. We found that mentally attending to someone else's verbal performance of brain-teaser tasks leads to similar results as in self-performing the same tasks. In this work we demonstrated that a single auditory selective attention task (i.e. mentally attending to someone else's verbal performance of mental subtraction) can modulate both induced and evoked changes in EEG, and be used for yes/no communication in an auditory scanning paradigm. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of Immediate Repetition in L2 Speaking Tasks: A Focused Study

ERIC Educational Resources Information Center

Bei, Gavin Xiaoyue

2013-01-01

This paper reports on a focused investigation into the immediate effects of oral narrative task repetition by two adult EFL learners of intermediate and high proficiency. Two participants performed a narrative speaking task after watching a cartoon video clip and repeated their performance three times, followed by a retrospective report in an…

Effects of the Protestant Work Ethic and Perceived Challenge on Time Allocated to an Experimental Task.

ERIC Educational Resources Information Center

Tang, Thomas Li-Ping

Goal-setting literature has suggested that specific, difficult goals will produce higher performance levels than easy goals. A difficult task or one with negative performance feedback may increase an individual's perceived challenge of the task which may in turn enhance his motivation. Effects of the Protestant work ethic and perceived challenge…

Bottom-Up Influences on Voluntary Task Switching: The Elusive Homunculus Escapes

ERIC Educational Resources Information Center

Yeung, Nick

2010-01-01

Voluntary action can be studied by giving participants free choice over which task to perform in response to each presented stimulus. In such experiments, performance costs are observed when participants choose to switch tasks from the previous trial. It has been proposed that these costs primarily index the time-consuming operation of top-down…

Do frailty and cognitive impairment affect dual-task cost during walking in the oldest old institutionalized patients?

PubMed

Cadore, Eduardo L; Casas-Herrero, Alvaro; Zambom-Ferraresi, Fabricio; Martínez-Ramírez, Alicia; Millor, Nora; Gómez, Marisol; Moneo, Ana B Bays; Izquierdo, Mikel

2015-12-01

The objective of this study was to investigate dual-task costs in several elderly populations, including robust oldest old, frail oldest old with MCI, frail oldest old without MCI, and frail elderly with dementia. Sixty-four elderly men and women categorized into frail without MCI (age 93.4 ± 3.2 years, n = 20), frail with MCI (age 92.4 ± 4.2 years, n = 13), robust (age 88.2 ± 4.1 years, n = 10), and patients with dementia (age 88.1 ± 5.1 years, n = 21). Five-meter gait ability and timed-up-and-go (TUG) tests with single and dual-task performance were assessed in the groups. Dual-task cost in both 5-m habitual gait velocity test and TUG test was calculated by the time differences between single and dual-task performance. The robust group exhibited better 5-m gait and TUG test performances in the single and dual-task conditions compared with the other three groups (P < 0.001), and the frail and frail + MCI groups exhibited better performances than the dementia group (P < 0.001). No significant differences were observed between the frail and frail + MCI groups. However, all groups exhibited lower gait velocities in the verbal and arithmetic task conditions, but the dual-task cost of the groups were similar. Robust individuals exhibited superior single and dual-task walking performances than the other three groups, and the frail and frail + MCI individuals exhibited performances that were superior to those of the patients with dementia. However, the dual-task costs, i.e., the changes in gait performance when elderly participants switch from a single to a dual task, were similar among all four of the investigated groups. Therefore, these results demonstrated that the magnitude of the impairment in gait pattern is independent of frailty and cognitive impairment status.

Psychomotor performance measured in a virtual environment correlates with technical skills in the operating room.

PubMed

Kundhal, Pavi S; Grantcharov, Teodor P

2009-03-01

This study was conducted to validate the role of virtual reality computer simulation as an objective method for assessing laparoscopic technical skills. The authors aimed to investigate whether performance in the operating room, assessed using a modified Objective Structured Assessment of Technical Skill (OSATS), correlated with the performance parameters registered by a virtual reality laparoscopic trainer (LapSim). The study enrolled 10 surgical residents (3 females) with a median of 5.5 years (range, 2-6 years) since graduation who had similar limited experience in laparoscopic surgery (median, 5; range, 1-16 laparoscopic cholecystectomies). All the participants performed three repetitions of seven basic skills tasks on the LapSim laparoscopic trainer and one laparoscopic cholecystectomy in the operating room. The operating room procedure was video recorded and blindly assessed by two independent observers using a modified OSATS rating scale. Assessment in the operating room was based on three parameters: time used, error score, and economy of motion score. During the tasks on the LapSim, time, error (tissue damage and millimeters of tissue damage [tasks 2-6], error score [incomplete target areas, badly placed clips, and dropped clips [task 7]), and economy of movement parameters (path length and angular path) were registered. The correlation between time, economy, and error parameters during the simulated tasks and the operating room procedure was statistically assessed using Spearman's test. Significant correlations were demonstrated between the time used to complete the operating room procedure and time used for task 7 (r (s) = 0.74; p = 0.015). The error score demonstrated during the laparoscopic cholecystectomy correlated well with the tissue damage in three of the seven tasks (p < 0.05), the millimeters of tissue damage during two of the tasks, and the error score in task 7 (r (s) = 0.67; p = 0.034). Furthermore, statistically significant correlations were observed between the economy of motion score from the operative procedure and LapSim's economy parameters (path length and angular path in six of the tasks) (p < 0.05). The current study demonstrated significant correlations between operative performance in the operating room (assessed using a well-validated rating scale) and psychomotor performance in virtual environment assessed by a computer simulator. This provides strong evidence for the validity of the simulator system as an objective tool for assessing laparoscopic skills. Virtual reality simulation can be used in practice to assess technical skills relevant for minimally invasive surgery.

A comparison of the real-time controllability of pattern recognition to conventional myoelectric control for discrete and simultaneous movements

PubMed Central

2014-01-01

Myoelectric control has been used for decades to control powered upper limb prostheses. Conventional, amplitude-based control has been employed to control a single prosthesis degree of freedom (DOF) such as closing and opening of the hand. Within the last decade, new and advanced arm and hand prostheses have been constructed that are capable of actuating numerous DOFs. Pattern recognition control has been proposed to control a greater number of DOFs than conventional control, but has traditionally been limited to sequentially controlling DOFs one at a time. However, able-bodied individuals use multiple DOFs simultaneously, and it may be beneficial to provide amputees the ability to perform simultaneous movements. In this study, four amputees who had undergone targeted motor reinnervation (TMR) surgery with previous training using myoelectric prostheses were configured to use three control strategies: 1) conventional amplitude-based myoelectric control, 2) sequential (one-DOF) pattern recognition control, 3) simultaneous pattern recognition control. Simultaneous pattern recognition was enabled by having amputees train each simultaneous movement as a separate motion class. For tasks that required control over just one DOF, sequential pattern recognition based control performed the best with the lowest average completion times, completion rates and length error. For tasks that required control over 2 DOFs, the simultaneous pattern recognition controller performed the best with the lowest average completion times, completion rates and length error compared to the other control strategies. In the two strategies in which users could employ simultaneous movements (conventional and simultaneous pattern recognition), amputees chose to use simultaneous movements 78% of the time with simultaneous pattern recognition and 64% of the time with conventional control for tasks that required two DOF motions to reach the target. These results suggest that when amputees are given the ability to control multiple DOFs simultaneously, they choose to perform tasks that utilize multiple DOFs with simultaneous movements. Additionally, they were able to perform these tasks with higher performance (faster speed, lower length error and higher completion rates) without losing substantial performance in 1 DOF tasks. PMID:24410948

Relationship between binocular vision, visual acuity, and fine motor skills.

PubMed

O'Connor, Anna R; Birch, Eileen E; Anderson, Susan; Draper, Hayley

2010-12-01

The aims of this study were to analyze the relationship between the performance on fine motor skills tasks and peripheral and bifoveal sensory fusion, phasic and tonic motor fusion, the level of visual acuity (VA) in the poorer seeing eye, and the interocular VA difference. Subjects aged 12 to 28 years with a range of levels of binocular vision and VA performed three tasks: Purdue pegboard (number of pegs placed in 30 s), bead threading task (with two sizes of bead to increase the difficulty, time taken to thread a fixed number of beads), and a water pouring task (accuracy and time to pour a fixed quantity into five glass cylinders). Ophthalmic measures included peripheral (Worth 4 dot) and bifoveal (4 prism diopter) sensory fusion, phasic (prism bar) and tonic (Risley rotary prism) motor fusion ranges, and monocular VA. One hundred twenty-one subjects with a mean age of 18.8 years were tested; 18.2% had a manifest strabismus. Performance on fine motor skills tasks was significantly better in subjects with sensory and motor fusion compared with those without for most tasks, with significant differences between those with and without all measures of fusion on the pegboard and bead task. Both the acuity in the poorer seeing eye (highest r value of all motor tasks = 0.43) and the interocular acuity difference were statistically significantly related to performance on the motor skill tasks. Both sensory and motor fusion and good VA in both eyes are of benefit in the performance of fine motor skills tasks, with the presence of some binocular vision being beneficial compared with no fusion on certain sensorimotor tasks. This evidence supports the need to maximize fusion and VA outcomes.

Balancing a U-Shaped Assembly Line by Applying Nested Partitions Method

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

Bhagwat, Nikhil V.

2005-01-01

In this study, we applied the Nested Partitions method to a U-line balancing problem and conducted experiments to evaluate the application. From the results, it is quite evident that the Nested Partitions method provided near optimal solutions (optimal in some cases). Besides, the execution time is quite short as compared to the Branch and Bound algorithm. However, for larger data sets, the algorithm took significantly longer times for execution. One of the reasons could be the way in which the random samples are generated. In the present study, a random sample is a solution in itself which requires assignment ofmore » tasks to various stations. The time taken to assign tasks to stations is directly proportional to the number of tasks. Thus, if the number of tasks increases, the time taken to generate random samples for the different regions also increases. The performance index for the Nested Partitions method in the present study was the number of stations in the random solutions (samples) generated. The total idle time for the samples can be used as another performance index. ULINO method is known to have used a combination of bounds to come up with good solutions. This approach of combining different performance indices can be used to evaluate the random samples and obtain even better solutions. Here, we used deterministic time values for the tasks. In industries where majority of tasks are performed manually, the stochastic version of the problem could be of vital importance. Experimenting with different objective functions (No. of stations was used in this study) could be of some significance to some industries where in the cost associated with creation of a new station is not the same. For such industries, the results obtained by using the present approach will not be of much value. Labor costs, task incompletion costs or a combination of those can be effectively used as alternate objective functions.« less

Self-paced preparation for a task switch eliminates attentional inertia but not the performance switch cost.

PubMed

Longman, Cai S; Lavric, Aureliu; Monsell, Stephen

2017-06-01

The performance overhead associated with changing tasks (the "switch cost") usually diminishes when the task is specified in advance but is rarely eliminated by preparation. A popular account of the "residual" (asymptotic) switch cost is that it reflects "task-set inertia": carry-over of task-set parameters from the preceding trial(s). New evidence for a component of "task-set inertia" comes from eye-tracking, where the location associated with the previously (but no longer) relevant task is fixated preferentially over other irrelevant locations, even when preparation intervals are generous. Might such limits in overcoming task-set inertia in general, and "attentional inertia" in particular, result from suboptimal scheduling of preparation when the time available is outside one's control? In the present study, the stimulus comprised 3 digits located at the points of an invisible triangle, preceded by a central verbal cue specifying which of 3 classification tasks to perform, each consistently applied to just 1 digit location. The digits were presented only when fixation moved away from the cue, thus giving the participant control over preparation time. In contrast to our previous research with experimenter-determined preparation intervals, we found no sign of attentional inertia for the long preparation intervals. Self-paced preparation reduced but did not eliminate the performance switch cost-leaving a clear residual component in both reaction time and error rates. That the scheduling of preparation accounts for some, but not all, components of the residual switch cost, challenges existing accounts of the switch cost, even those which distinguish between preparatory and poststimulus reconfiguration processes. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

The Influence of Feedback on Task-Switching Performance: A Drift Diffusion Modeling Account.

PubMed

Cohen Hoffing, Russell; Karvelis, Povilas; Rupprechter, Samuel; Seriès, Peggy; Seitz, Aaron R

2018-01-01

Task-switching is an important cognitive skill that facilitates our ability to choose appropriate behavior in a varied and changing environment. Task-switching training studies have sought to improve this ability by practicing switching between multiple tasks. However, an efficacious training paradigm has been difficult to develop in part due to findings that small differences in task parameters influence switching behavior in a non-trivial manner. Here, for the first time we employ the Drift Diffusion Model (DDM) to understand the influence of feedback on task-switching and investigate how drift diffusion parameters change over the course of task switch training. We trained 316 participants on a simple task where they alternated sorting stimuli by color or by shape. Feedback differed in six different ways between subjects groups, ranging from No Feedback (NFB) to a variety of manipulations addressing trial-wise vs. Block Feedback (BFB), rewards vs. punishments, payment bonuses and different payouts depending upon the trial type (switch/non-switch). While overall performance was found to be affected by feedback, no effect of feedback was found on task-switching learning. Drift Diffusion Modeling revealed that the reductions in reaction time (RT) switch cost over the course of training were driven by a continually decreasing decision boundary. Furthermore, feedback effects on RT switch cost were also driven by differences in decision boundary, but not in drift rate. These results reveal that participants systematically modified their task-switching performance without yielding an overall gain in performance.

Training high performance skills using above real-time training

NASA Technical Reports Server (NTRS)

Guckenberger, Dutch; Uliano, Kevin C.; Lane, Norman E.

1993-01-01

The Above Real-Time Training (ARTT) concept is a unique approach to training high performance skills. ARTT refers to a training paradigm that places the operator in a simulated environment that functions at faster than normal time. Such a training paradigm represents a departure from the intuitive, but not often supported, feeling that the best practice is determined by the training environment with the highest fidelity. This approach is hypothesized to provide greater 'transfer value' per simulation trial, by incorporating training techniques and instructional features into the simulator. These techniques allow individuals to acquire these critical skills faster and with greater retention. ARTT also allows an individual trained in 'fast time' to operate at what appears to be a more confident state, when the same task is performed in a real-time environment. Two related experiments are discussed. The findings appear to be consistent with previous findings that show positive effects of task variation during training. Moreover, ARTT has merit in improving or maintaining transfer with sharp reductions in training time. There are indications that the effectiveness of ARTT varies as a function of task content and possibly task difficulty. Other implications for ARTT are discussed along with future research directions.

The JFK BIG study: the impact of LSVT BIG® on dual task walking and mobility in persons with Parkinson's disease.

PubMed

Isaacson, Sara; O'Brien, Ashley; Lazaro, Jennifer D; Ray, Arlen; Fluet, Gerard

2018-04-01

[Purpose] The aim of this study was to test the hypothesis that Lee Silverman Voice Treatment-BIG decreases the negative impact of hypokinesia on dual task performance in persons with Parkinson's disease. [Subjects and Methods] The records of 114 patients with Parkinson's admitted to outpatient rehabilitation at a suburban hospital were reviewed. Demographics and data for 8 outcome measures were extracted for subjects that completed 14 of 16 sessions of BIG. 93 of these subjects had records of pre and post-test Timed Up and Go, Timed Up and Go Motor, and Timed Up and Go Cognitive scores. Average age was 68.4 years (SD=10.6) and average disease duration was 4.9 years (SD=5.3). [Results] Subjects demonstrated statistically significant improvements for Timed Up and Go (3.3 SD=4.5), Timed Up and Go Motor (4.4 SD=5.8) and Timed Up and Go Cognitive (4.7 SD=5.4). Concurrent motor and cognitive performance remained stable. Dual task cost decreased at a statistically significant level for Timed Up and Go Cognitive (7% SD=31%) but not Motor (4% SD=32%). [Conclusion] These findings suggest that cueing strategies associated with LSVT BIG become internalized and decrease the negative impact of hypokinesia on mobility and cognitive performance while performing two tasks simultaneously in persons with Parkinson's.

The effects of instructional sets on reactions to and performance on an intelligent tutoring system

NASA Technical Reports Server (NTRS)

Johnson, Debra Steele

1993-01-01

The effects of a contextual factor, i.e., task instructions, on performance on and reactions to an Intellegent Tutoring System (ITS) training Remote Manipulator System (RMS) tasks were examined. The results supported the first prediction that task instructions could be used to successfully induce a mastery versus an achievement orientation. Previous research suggests that a mastery orientation can result in beneficial effects on learning and performance of complex tasks. Furthermore, the results supported the second prediction that a mastery orientation would have beneficial effects on learning and performance as well as affective and cognitive reactions to the ITS tasks. Moreover, the results indicated that a mastery orientation was especially beneficial for the more complex ITS tasks and later in task practice, i.e., when a task was performed for the second time. A mastery orientation is posited to have its beneficial effects by focusing more effort and attention on task performance. Conclusions are drawn with some caution due to the small number of subjects, although the results for these subjects were consistent across multiple trials and multiple measures of performance. ITS designers are urged to consider contextual factors such as task instructions and feedback in terms of their potential to induce a mastery versus an achievement orientation.

Tactile memory of deaf-blind adults on four tasks.

PubMed

Arnold, Paul; Heiron, Karen

2002-02-01

The performance of ten deaf-blind and ten sighted-hearing participants on four tactile memory tasks was investigated. Recognition and recall memory tasks and a matching pairs game were used. It was hypothesized that deaf-blind participants would be superior on each task. Performance was measured in terms of the time taken, and the number of items correctly recalled. In Experiments 1 and 2, which measured recognition memory in terms of the time taken to remember target items, the hypothesis was supported, but not by the length of time taken to recognize the target items, or for the number of target items correctly identified. The hypothesis was supported by Experiment 3, which measured recall memory, with regard to time taken to complete some of the tasks but not for the number of correctly recalled positions. Experiment 4, which used the matching pairs game, supported the hypothesis in terms of both time taken and the number of moves required. It is concluded that the deaf-blind people's tactile encoding is more efficient than that of sighted-hearing people, and that it is probable that their storage and retrieval are normal.

Comparison of visual and emotional continuous performance test related to sequence of presentation, gender and age.

PubMed

Markovska-Simoska, S; Pop-Jordanova, N

2009-07-01

(Full text is available at http://www.manu.edu.mk/prilozi). Continous Performance Tests (CPTs) form a group of paradigms for the evaluation of attention and, to a lesser degree, the response inhibition (or disinhibition) component of executive control. The object of this study was to compare performance on a CPT using both visual and emotional tasks in 46 normal adult subjects. In particular, it was to examine the effects of the type of task (VCPT or ECPT), sequence of presentation, and gender/age influence on performance as measured errors of omission, errors of commission, reaction time and variation of reaction time. From the results we can assume that there are significantly worse performance parameters for ECPT than VCPT tasks, with a probable explanation of the influence of emotional stimuli on attention and information-processing and no significant effect of order of presentation and gender on performance. Significant differences with more omission errors for older groups were obtained, showing better attention in younger subjects. Key words: VCPT, ECPT, omission errors, commission errors, reaction time, variation of reaction time, normal adults.

Strategic behavior, workload, and performance in task scheduling

NASA Technical Reports Server (NTRS)

Moray, Neville; Dessouky, Mohamed I.; Kijowski, Brian A.; Adapathya, Ravi

1991-01-01

Scheduling theory is proposed as a normative model for strategic behavior when operators are confronted by several tasks, all of which should be completed within a fixed time span, and when they are free to choose the order in which the tasks should be done. Three experiments are described to investigate the effect of knowing the correct scheduling rule on the efficiency of performance, subjective workload, and choice of strategy under different conditions of time pressure. The most potent effects are from time pressure. The reasons for the weak effect of knowing the rules are discussed, and implications for strategic behavior, displays, and decision aids are indicated.

Hotline Complaint Regarding A Defense Contract Audit Agency Employee Conducting Private For-Profit Tax Business Activity on Government Time and Using Government Equipment

DTIC Science & Technology

2011-06-28

auditors that have private businesses from performing private business tasks on Government time while teleworking . • Contact the U.S. Department of the...profit businesses and telework to perform tasks associated with their private businesses on Government time. Although teleworking did not cause the... teleworking , it increases the vulnerability that an unethical employee will misuse Government time. DCAA employs approximately 4,000 auditors, which is more

The Impact of Students' Temporal Perspectives on Time-on-Task and Learning Performance in Game Based Learning

ERIC Educational Resources Information Center

Romero, Margarida; Usart, Mireia

2013-01-01

The use of games for educational purposes has been considered as a learning methodology that attracts the students' attention and may allow focusing individuals on the learning activity through the [serious games] SG game dynamic. Based on the hypothesis that students' Temporal Perspective has an impact on learning performance and time-on-task,…

Exploring the repetition bias in voluntary task switching.

PubMed

Mittelstädt, Victor; Dignath, David; Schmidt-Ott, Magdalena; Kiesel, Andrea

2018-01-01

In the voluntary task-switching paradigm, participants are required to randomly select tasks. We reasoned that the consistent finding of a repetition bias (i.e., participants repeat tasks more often than expected by chance) reflects reasonable adaptive task selection behavior to balance the goal of random task selection with the goals to minimize the time and effort for task performance. We conducted two experiments in which participants were provided with variable amount of preview for the non-chosen task stimuli (i.e., potential switch stimuli). We assumed that switch stimuli would initiate some pre-processing resulting in improved performance in switch trials. Results showed that reduced switch costs due to extra-preview in advance of each trial were accompanied by more task switches. This finding is in line with the characteristics of rational adaptive behavior. However, participants were not biased to switch tasks more often than chance despite large switch benefits. We suggest that participants might avoid effortful additional control processes that modulate the effects of preview on task performance and task choice.

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.

Blue-Enriched White Light Enhances Physiological Arousal But Not Behavioral Performance during Simulated Driving at Early Night

PubMed Central

Rodríguez-Morilla, Beatriz; Madrid, Juan A.; Molina, Enrique; Correa, Angel

2017-01-01

Vigilance usually deteriorates over prolonged driving at non-optimal times of day. Exposure to blue-enriched light has shown to enhance arousal, leading to behavioral benefits in some cognitive tasks. However, the cognitive effects of long-wavelength light have been less studied and its effects on driving performance remained to be addressed. We tested the effects of a blue-enriched white light (BWL) and a long-wavelength orange light (OL) vs. a control condition of dim light on subjective, physiological and behavioral measures at 21:45 h. Neurobehavioral tests included the Karolinska Sleepiness Scale and subjective mood scale, recording of distal-proximal temperature gradient (DPG, as index of physiological arousal), accuracy in simulated driving and reaction time in the auditory psychomotor vigilance task. The results showed that BWL decreased the DPG (reflecting enhanced arousal), while it did not improve reaction time or driving performance. Instead, blue light produced larger driving errors than OL, while performance in OL was stable along time on task. These data suggest that physiological arousal induced by light does not necessarily imply cognitive improvement. Indeed, excessive arousal might deteriorate accuracy in complex tasks requiring precision, such as driving. PMID:28690558

Task-Driven Evaluation of Aggregation in Time Series Visualization

PubMed Central

Albers, Danielle; Correll, Michael; Gleicher, Michael

2014-01-01

Many visualization tasks require the viewer to make judgments about aggregate properties of data. Recent work has shown that viewers can perform such tasks effectively, for example to efficiently compare the maximums or means over ranges of data. However, this work also shows that such effectiveness depends on the designs of the displays. In this paper, we explore this relationship between aggregation task and visualization design to provide guidance on matching tasks with designs. We combine prior results from perceptual science and graphical perception to suggest a set of design variables that influence performance on various aggregate comparison tasks. We describe how choices in these variables can lead to designs that are matched to particular tasks. We use these variables to assess a set of eight different designs, predicting how they will support a set of six aggregate time series comparison tasks. A crowd-sourced evaluation confirms these predictions. These results not only provide evidence for how the specific visualizations support various tasks, but also suggest using the identified design variables as a tool for designing visualizations well suited for various types of tasks. PMID:25343147

Measuring moment-to-moment pilot workload using synchronous presentations of secondary tasks in a motion-base trainer

NASA Technical Reports Server (NTRS)

Bortolussi, Michael R.; Hart, Sandra G.; Shively, Robert J.

1987-01-01

A simulation was conducted to determine whether the sensitivity of secondary task measures of pilot workload could be improved by synchronizing their presentation to the occurrence of specific events or pilot actions. This synchronous method of presentation was compared to the more typical asynchronous method, where secondary task presentations are independent of pilot's flight-related activities. Twelve pilots flew low- and high-difficulty scenarios in a motion-base trainer with and without concurrent secondary tasks (e.g., choice reaction time and time production). The difficulty of each scenario was manipulated by the addition of 21 flight-related tasks superimposed on a standard approach and landing sequence. The insertion of the secondary tasks did not affect primary flight performance. However, secondary task performance did reflect workload differences between scenarios and among flight segments within scenarios, replicating the results of an earlier study in which the secondary tasks were presented asynchronously (Bortolussi et al., 1986).

A spiking neural integrator model of the adaptive control of action by the medial prefrontal cortex.

PubMed

Bekolay, Trevor; Laubach, Mark; Eliasmith, Chris

2014-01-29

Subjects performing simple reaction-time tasks can improve reaction times by learning the expected timing of action-imperative stimuli and preparing movements in advance. Success or failure on the previous trial is often an important factor for determining whether a subject will attempt to time the stimulus or wait for it to occur before initiating action. The medial prefrontal cortex (mPFC) has been implicated in enabling the top-down control of action depending on the outcome of the previous trial. Analysis of spike activity from the rat mPFC suggests that neural integration is a key mechanism for adaptive control in precisely timed tasks. We show through simulation that a spiking neural network consisting of coupled neural integrators captures the neural dynamics of the experimentally recorded mPFC. Errors lead to deviations in the normal dynamics of the system, a process that could enable learning from past mistakes. We expand on this coupled integrator network to construct a spiking neural network that performs a reaction-time task by following either a cue-response or timing strategy, and show that it performs the task with similar reaction times as experimental subjects while maintaining the same spiking dynamics as the experimentally recorded mPFC.

Virtual reality robotic surgery warm-up improves task performance in a dry laboratory environment: a prospective randomized controlled study.

PubMed

Lendvay, Thomas S; Brand, Timothy C; White, Lee; Kowalewski, Timothy; Jonnadula, Saikiran; Mercer, Laina D; Khorsand, Derek; Andros, Justin; Hannaford, Blake; Satava, Richard M

2013-06-01

Preoperative simulation warm-up has been shown to improve performance and reduce errors in novice and experienced surgeons, yet existing studies have only investigated conventional laparoscopy. We hypothesized that a brief virtual reality (VR) robotic warm-up would enhance robotic task performance and reduce errors. In a 2-center randomized trial, 51 residents and experienced minimally invasive surgery faculty in General Surgery, Urology, and Gynecology underwent a validated robotic surgery proficiency curriculum on a VR robotic simulator and on the da Vinci surgical robot (Intuitive Surgical Inc). Once they successfully achieved performance benchmarks, surgeons were randomized to either receive a 3- to 5-minute VR simulator warm-up or read a leisure book for 10 minutes before performing similar and dissimilar (intracorporeal suturing) robotic surgery tasks. The primary outcomes compared were task time, tool path length, economy of motion, technical, and cognitive errors. Task time (-29.29 seconds, p = 0.001; 95% CI, -47.03 to -11.56), path length (-79.87 mm; p = 0.014; 95% CI, -144.48 to -15.25), and cognitive errors were reduced in the warm-up group compared with the control group for similar tasks. Global technical errors in intracorporeal suturing (0.32; p = 0.020; 95% CI, 0.06-0.59) were reduced after the dissimilar VR task. When surgeons were stratified by earlier robotic and laparoscopic clinical experience, the more experienced surgeons (n = 17) demonstrated significant improvements from warm-up in task time (-53.5 seconds; p = 0.001; 95% CI, -83.9 to -23.0) and economy of motion (0.63 mm/s; p = 0.007; 95% CI, 0.18-1.09), and improvement in these metrics was not statistically significantly appreciated in the less-experienced cohort (n = 34). We observed significant performance improvement and error reduction rates among surgeons of varying experience after VR warm-up for basic robotic surgery tasks. In addition, the VR warm-up reduced errors on a more complex task (robotic suturing), suggesting the generalizability of the warm-up. Copyright © 2013 American College of Surgeons. All rights reserved.

Virtual Reality Robotic Surgery Warm-Up Improves Task Performance in a Dry Lab Environment: A Prospective Randomized Controlled Study

PubMed Central

Lendvay, Thomas S.; Brand, Timothy C.; White, Lee; Kowalewski, Timothy; Jonnadula, Saikiran; Mercer, Laina; Khorsand, Derek; Andros, Justin; Hannaford, Blake; Satava, Richard M.

2014-01-01

Background Pre-operative simulation “warm-up” has been shown to improve performance and reduce errors in novice and experienced surgeons, yet existing studies have only investigated conventional laparoscopy. We hypothesized a brief virtual reality (VR) robotic warm-up would enhance robotic task performance and reduce errors. Study Design In a two-center randomized trial, fifty-one residents and experienced minimally invasive surgery faculty in General Surgery, Urology, and Gynecology underwent a validated robotic surgery proficiency curriculum on a VR robotic simulator and on the da Vinci surgical robot. Once successfully achieving performance benchmarks, surgeons were randomized to either receive a 3-5 minute VR simulator warm-up or read a leisure book for 10 minutes prior to performing similar and dissimilar (intracorporeal suturing) robotic surgery tasks. The primary outcomes compared were task time, tool path length, economy of motion, technical and cognitive errors. Results Task time (-29.29sec, p=0.001, 95%CI-47.03,-11.56), path length (-79.87mm, p=0.014, 95%CI -144.48,-15.25), and cognitive errors were reduced in the warm-up group compared to the control group for similar tasks. Global technical errors in intracorporeal suturing (0.32, p=0.020, 95%CI 0.06,0.59) were reduced after the dissimilar VR task. When surgeons were stratified by prior robotic and laparoscopic clinical experience, the more experienced surgeons(n=17) demonstrated significant improvements from warm-up in task time (-53.5sec, p=0.001, 95%CI -83.9,-23.0) and economy of motion (0.63mm/sec, p=0.007, 95%CI 0.18,1.09), whereas improvement in these metrics was not statistically significantly appreciated in the less experienced cohort(n=34). Conclusions We observed a significant performance improvement and error reduction rate among surgeons of varying experience after VR warm-up for basic robotic surgery tasks. In addition, the VR warm-up reduced errors on a more complex task (robotic suturing) suggesting the generalizability of the warm-up. PMID:23583618

The effects of display-control I/O, compatibility, and integrality on dual-task performance and subjective workload

NASA Technical Reports Server (NTRS)

Tsang, Pamela S.; Hart, Sandra G.; Vidulich, Michael A.

1987-01-01

The utility of speech technology was evaluated in terms of three dual task principles: resource competition between the time shared tasks, stimulus central processing response compatibility, and task integrality. Empirical support for these principles was reviewed. Two studies investigating the interactive effects of the three principles were described. Objective performance and subjective workload ratings for both single and dual tasks were examined. It was found that the single task measures were not necessarily good predictors for the dual task measures. It was shown that all three principles played an important role in determining an optimal task configuration. This was reflected in both the performance measures and the subjective measures. Therefore, consideration of all three principles is required to insure proper use of speech technology in a complex environment.

Modeling take-over performance in level 3 conditionally automated vehicles.

PubMed

Gold, Christian; Happee, Riender; Bengler, Klaus

2018-07-01

Taking over vehicle control from a Level 3 conditionally automated vehicle can be a demanding task for a driver. The take-over determines the controllability of automated vehicle functions and thereby also traffic safety. This paper presents models predicting the main take-over performance variables take-over time, minimum time-to-collision, brake application and crash probability. These variables are considered in relation to the situational and driver-related factors time-budget, traffic density, non-driving-related task, repetition, the current lane and driver's age. Regression models were developed using 753 take-over situations recorded in a series of driving simulator experiments. The models were validated with data from five other driving simulator experiments of mostly unrelated authors with another 729 take-over situations. The models accurately captured take-over time, time-to-collision and crash probability, and moderately predicted the brake application. Especially the time-budget, traffic density and the repetition strongly influenced the take-over performance, while the non-driving-related tasks, the lane and drivers' age explained a minor portion of the variance in the take-over performances. Copyright © 2017 Elsevier Ltd. All rights reserved.

Age-Related Intraindividual Performance Variability with Practice

ERIC Educational Resources Information Center

Miller, Suzanne Bonneau; Odell, Katharine H.

2007-01-01

Fluctuations in cognitive task performance in older individuals have been reported. To examine intraindividual variability as a function of practice, 34 younger and 34 older female participants, aged 20-30 years and 70-82 years, respectively, performed a reading span task 16 times over four sessions. Each individual's recall accuracy was analyzed…

EEG Correlates of Fluctuation in Cognitive Performance in an Air Traffic Control Task

DTIC Science & Technology

2014-11-01

using non-parametric statistical analysis to identify neurophysiological patterns due to the time-on-task effect. Significant changes in EEG power...EEG, Cognitive Performance, Power Spectral Analysis , Non-Parametric Analysis Document is available to the public through the Internet...3 Performance Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 EEG

Determinants explaining the variability of hand-transmitted vibration emissions from two different work tasks: grinding and cutting using angle grinders.

PubMed

Liljelind, Ingrid; Pettersson, Hans; Nilsson, Leif; Wahlström, Jens; Toomingas, Allan; Lundström, Ronnie; Burström, Lage

2013-10-01

There are numerous factors including physical, biomechanical, and individual that influence exposure to hand-transmitted vibration (HTV) and cause variability in the exposure measurements. Knowledge of exposure variability and determinants of exposure could be used to improve working conditions. We performed a quasi-experimental study, where operators performed routine work tasks in order to obtain estimates of the variance components and to evaluate the effect of determinants, such as machine-wheel combinations and individual operator characteristics. Two pre-defined simulated work tasks were performed by 11 operators: removal of a weld puddle of mild steel and cutting of a square steel pipe. In both tasks, four angle grinders were used, two running on compressed air and two electrically driven. Two brands of both grinding and cutting wheels were used. Each operator performed both tasks twice in a random order with each grinder and wheel and the time to complete each task was recorded. Vibration emission values were collected and the wheel wear was measured as loss of weight. Operators' characteristics collected were as follows: age, body height and weight, length and volume of their hands, maximum hand grip force, and length of work experience with grinding machines (years). The tasks were also performed by one operator who used four machines of the same brand. Mixed and random effects models were used in the statistical evaluation. The statistical evaluation was performed for grinding and cutting separately and we used a measure referring to the sum of the 1-s r.m.s. average frequency-weighted acceleration over time for completing the work task (a(sa)). Within each work task, there was a significant effect as a result of the determinants 'the machine used', 'wheel wear', and 'time taken to complete the task'. For cutting, 'the brand of wheel' used also had a significant effect. More than 90% of the inherent variability in the data was explained by the determinants. The two electrically powered machines had a mean a(sa) that was 2.6 times higher than the two air-driven machines. For cutting, the effect of the brand of wheel on a(sa) was ~0.1 times. The a(sa) increased both with increasing wheel wear and with time taken to complete the work task. However, there were also a number of interaction effects which, to a minor extent, modified the a(sa). Only a minor part (1%) of the total variability was attributed to the operator: for cutting, the volume of the hands, maximum grip force, and body weight were significant, while for grinding, it was the maximum grip force. There was no clear difference in a(sa) between the four copies of the same brand of each machine. By including determinants that were attributed to the brand of both machine and wheel used as well as the time taken to complete the work task, we were able to explain >90% of the variability. The dominating determinant was the brand of the machine. Little variability was found between operators, indicating that the overall effect as due to the operator was small.

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

PubMed

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

2017-07-01

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

The effects of moderate fatigue on dynamic balance control and attentional demands.

PubMed

Simoneau, Martin; Bégin, François; Teasdale, Normand

2006-09-28

During daily activities, the active control of balance often is a task per se (for example, when standing in a moving bus). Other constraints like fatigue can add to the complexity of this balance task. In the present experiment, we examined how moderate fatigue induced by fast walking on a treadmill challenged dynamic balance control. We also examined if the attentional demands for performing the balance task varied with fatigue. Subjects (n = 10) performed simultaneously a dynamic balance control task and a probe reaction time task (RT) (serving as an indicator of attentional demands) before and after three periods of moderate fatigue (fast walking on a treadmill). For the balance control task, the real-time displacement of the centre of pressure (CP) was provided on a monitor placed in front of the subject, at eye level. Subjects were asked to keep their CP within a target (moving box) moving upward and downward on the monitor. The tracking performance was measured (time spent outside the moving box) and the CP behavior analyzed (mean CP speed and mean frequency of the CP velocity). Moderate fatigue led to an immediate decrement of the performance on the balance control task; increase of the percentage of time spent outside the box and increase of the mean CP speed. Across the three fatigue periods, subjects improved their tracking performance and reduced their mean CP speed. This was achieved by increasing their frequency of actions; mean frequency of the CP velocity were higher for the fatigue periods than for the no fatigue periods. Fatigue also induced an increase in the attentional demands suggesting that more cognitive resources had to be allocated to the balance task with than without fatigue. Fatigue induced by fast walking had an initial negative impact on the control of balance. Nonetheless, subjects were able to compensate the effect of the moderate fatigue by increasing the frequency of actions. This adaptation, however, required that a greater proportion of the cognitive resources be allocated to the active control of the balance task.

A comparison of deployed occupational tasks performed by different types of military battalions and resulting low back pain.

PubMed

Roy, Tanja C; Lopez, Heather P

2013-08-01

With deployment Soldiers must now wear body armor and additional equipment while performing occupational tasks, representing a large demand that has not been considered when studying military occupations. The purpose of this study was to: (1) describe tasks required by different occupational battalions within a Brigade Combat Team; (2) establish the incidence of low back pain (LBP) in each battalion and; (3) determine which tasks predict LBP within the different battalions. This was a prospective cohort study investigating 805 Soldiers in a Brigade Combat Team deployed to Afghanistan for 1 year. Demographic, occupational, and fitness variables were recorded. There was no difference in time spent on fitness training between the battalions. Occupational tasks performed by deployed Soldiers vary in the level of physical demand between battalions. Infantry had the highest fitness score (257); wore the heaviest equipment (70 lb.); spent the most time wearing body armor (49 hours/week), performing dismounted patrol (29 hours/week), and lifting objects (35 hours/week); spent the least amount of time working at a desk (14 hours/week); but had a similar incidence of LBP (77%) compared to other battalions. History of LBP and time spent wearing body armor were the two most consistent predictors of LBP across battalion types. Reprint & Copyright © 2013 Association of Military Surgeons of the U.S.

Dissociable effects of practice variability on learning motor and timing skills.

PubMed

Caramiaux, Baptiste; Bevilacqua, Frédéric; Wanderley, Marcelo M; Palmer, Caroline

2018-01-01

Motor skill acquisition inherently depends on the way one practices the motor task. The amount of motor task variability during practice has been shown to foster transfer of the learned skill to other similar motor tasks. In addition, variability in a learning schedule, in which a task and its variations are interweaved during practice, has been shown to help the transfer of learning in motor skill acquisition. However, there is little evidence on how motor task variations and variability schedules during practice act on the acquisition of complex motor skills such as music performance, in which a performer learns both the right movements (motor skill) and the right time to perform them (timing skill). This study investigated the impact of rate (tempo) variability and the schedule of tempo change during practice on timing and motor skill acquisition. Complete novices, with no musical training, practiced a simple musical sequence on a piano keyboard at different rates. Each novice was assigned to one of four learning conditions designed to manipulate the amount of tempo variability across trials (large or small tempo set) and the schedule of tempo change (randomized or non-randomized order) during practice. At test, the novices performed the same musical sequence at a familiar tempo and at novel tempi (testing tempo transfer), as well as two novel (but related) sequences at a familiar tempo (testing spatial transfer). We found that practice conditions had little effect on learning and transfer performance of timing skill. Interestingly, practice conditions influenced motor skill learning (reduction of movement variability): lower temporal variability during practice facilitated transfer to new tempi and new sequences; non-randomized learning schedule improved transfer to new tempi and new sequences. Tempo (rate) and the sequence difficulty (spatial manipulation) affected performance variability in both timing and movement. These findings suggest that there is a dissociable effect of practice variability on learning complex skills that involve both motor and timing constraints.

Acquisition of Motor and Cognitive Skills through Repetition in Typically Developing Children

PubMed Central

Magallón, Sara; Narbona, Juan; Crespo-Eguílaz, Nerea

2016-01-01

Background Procedural memory allows acquisition, consolidation and use of motor skills and cognitive routines. Automation of procedures is achieved through repeated practice. In children, improvement in procedural skills is a consequence of natural neurobiological development and experience. Methods The aim of the present research was to make a preliminary evaluation and description of repetition-based improvement of procedures in typically developing children (TDC). Ninety TDC children aged 6–12 years were asked to perform two procedural learning tasks. In an assembly learning task, which requires predominantly motor skills, we measured the number of assembled pieces in 60 seconds. In a mirror drawing learning task, which requires more cognitive functions, we measured time spent and efficiency. Participants were tested four times for each task: three trials were consecutive and the fourth trial was performed after a 10-minute nonverbal interference task. The influence of repeated practice on performance was evaluated by means of the analysis of variance with repeated measures and the paired-sample test. Correlation coefficients and simple linear regression test were used to examine the relationship between age and performance. Results TDC achieved higher scores in both tasks through repetition. Older children fitted more pieces than younger ones in assembling learning and they were faster and more efficient at the mirror drawing learning task. Conclusions These findings indicate that three consecutive trials at a procedural task increased speed and efficiency, and that age affected basal performance in motor-cognitive procedures. PMID:27384671

Acquisition of Motor and Cognitive Skills through Repetition in Typically Developing Children.

PubMed

Magallón, Sara; Narbona, Juan; Crespo-Eguílaz, Nerea

2016-01-01

Procedural memory allows acquisition, consolidation and use of motor skills and cognitive routines. Automation of procedures is achieved through repeated practice. In children, improvement in procedural skills is a consequence of natural neurobiological development and experience. The aim of the present research was to make a preliminary evaluation and description of repetition-based improvement of procedures in typically developing children (TDC). Ninety TDC children aged 6-12 years were asked to perform two procedural learning tasks. In an assembly learning task, which requires predominantly motor skills, we measured the number of assembled pieces in 60 seconds. In a mirror drawing learning task, which requires more cognitive functions, we measured time spent and efficiency. Participants were tested four times for each task: three trials were consecutive and the fourth trial was performed after a 10-minute nonverbal interference task. The influence of repeated practice on performance was evaluated by means of the analysis of variance with repeated measures and the paired-sample test. Correlation coefficients and simple linear regression test were used to examine the relationship between age and performance. TDC achieved higher scores in both tasks through repetition. Older children fitted more pieces than younger ones in assembling learning and they were faster and more efficient at the mirror drawing learning task. These findings indicate that three consecutive trials at a procedural task increased speed and efficiency, and that age affected basal performance in motor-cognitive procedures.

Testing the accuracy of timing reports in visual timing tasks with a consumer-grade digital camera.

PubMed

Smyth, Rachael E; Oram Cardy, Janis; Purcell, David

2017-06-01

This study tested the accuracy of a visual timing task using a readily available and relatively inexpensive consumer grade digital camera. A visual inspection time task was recorded using short high-speed video clips and the timing as reported by the task's program was compared to the timing as recorded in the video clips. Discrepancies in these two timing reports were investigated further and based on display refresh rate, a decision was made whether the discrepancy was large enough to affect the results as reported by the task. In this particular study, the errors in timing were not large enough to impact the results of the study. The procedure presented in this article offers an alternative method for performing a timing test, which uses readily available hardware and can be used to test the timing in any software program on any operating system and display.

Enhancing independent time-management skills of individuals with mental retardation using a Palmtop personal computer.

PubMed

Davies, Daniel K; Stock, Steven E; Wehmeyer, Michael L

2002-10-01

Achieving greater independence for individuals with mental retardation depends upon the acquisition of several key skills, including time-management and scheduling skills. The ability to perform tasks according to a schedule is essential to domains like independent living and employment. The use of a portable schedule prompting system to increase independence and self-regulation in time-management for individuals with mental retardation was examined. Twelve people with mental retardation participated in a comparison of their use of the technology system to perform tasks on a schedule with use of a written schedule. Results demonstrated the utility of a Palmtop computer with schedule prompting software to increase independence in the performance of vocational and daily living tasks by individuals with mental retardation.

The influences of obesity and age on functional performance during intermittent upper extremity tasks.

PubMed

Cavuoto, Lora A; Nussbaum, Maury A

2014-01-01

In this study, the main and interactive effects of obesity and age on functional performance were assessed during intermittent exertions involving the upper extremity. The prevalence of obesity has doubled over the past 30 years and this increase is associated with higher health care costs, rates of workplace injury, and lost workdays. Obesity and aging can modify job demands and affect worker capacity in terms of muscular and psychomotor function. However, there is a lack of empirical studies quantifying the work-relevant (or ergonomic) impacts related to task demands, capacities, and their potential imbalance. Eight obese and eight non-obese participants from each of two age groups (18-25 and 50-65 years) completed three endurance tasks involving fixed levels of task demands: hand grip, shoulder flexion, and a simulated assembly task using the upper extremity. Measures of functional performance including endurance, discomfort, motor control, and task performance were recorded for each of the task conditions. Endurance times were ∼60% longer for the non-obese group, and older participants had longer endurance times; however there was no evidence of interactive effects of obesity and age. Obesity also impaired functional performance, as indicated by higher rates of strength loss, increases in discomfort, and declines in task performance. These observed impairments may reflect underlying physiological differences among individuals who are obese, but that are independent of age. Obesity-related impairments may have implications for the design of work duration and demand level to prevent fatigue development for workers who are obese.

Real-time augmented feedback benefits robotic laparoscopic training.

PubMed

Judkins, Timothy N; Oleynikov, Dmitry; Stergiou, Nick

2006-01-01

Robotic laparoscopic surgery has revolutionized minimally invasive surgery for treatment of abdominal pathologies. However, current training techniques rely on subjective evaluation. There is a lack of research on the type of tasks that should be used for training. Robotic surgical systems also do not currently have the ability to provide feedback to the surgeon regarding success of performing tasks. We trained medical students on three laparoscopic tasks and provided real-time feedback of performance during training. We found that real-time feedback can benefit training if the feedback provides information that is not available through other means (grip force). Subjects that received grip force feedback applied less force when the feedback was removed. Other forms of feedback (speed and relative phase) did not aid or impede training. Secondly, a relatively short training period (10 trials for each task) significantly improved most objective measures of performance. We also showed that robotic surgical performance can be quantitatively measured and evaluated. Providing grip force feedback can make the surgeon more aware of the forces being applied to delicate tissue during surgery.

The effects of simulated fog and motion on simulator sickness in a driving simulator and the duration of after-effects.

PubMed

Dziuda, Lukasz; Biernacki, Marcin P; Baran, Paulina M; Truszczyński, Olaf E

2014-05-01

In the study, we checked: 1) how the simulator test conditions affect the severity of simulator sickness symptoms; 2) how the severity of simulator sickness symptoms changes over time; and 3) whether the conditions of the simulator test affect the severity of these symptoms in different ways, depending on the time that has elapsed since the performance of the task in the simulator. We studied 12 men aged 24-33 years (M = 28.8, SD = 3.26) using a truck simulator. The SSQ questionnaire was used to assess the severity of the symptoms of simulator sickness. Each of the subjects performed three 30-minute tasks running along the same route in a driving simulator. Each of these tasks was carried out in a different simulator configuration: A) fixed base platform with poor visibility; B) fixed base platform with good visibility; and C) motion base platform with good visibility. The measurement of the severity of the simulator sickness symptoms took place in five consecutive intervals. The results of the analysis showed that the simulator test conditions affect in different ways the severity of the simulator sickness symptoms, depending on the time which has elapsed since performing the task on the simulator. The simulator sickness symptoms persisted at the highest level for the test conditions involving the motion base platform. Also, when performing the tasks on the motion base platform, the severity of the simulator sickness symptoms varied depending on the time that had elapsed since performing the task. Specifically, the addition of motion to the simulation increased the oculomotor and disorientation symptoms reported as well as the duration of the after-effects. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Understanding neuromotor strategy during functional upper extremity tasks using symbolic dynamics.

PubMed

Nathan, Dominic E; Guastello, Stephen J; Prost, Robert W; Jeutter, Dean C

2012-01-01

The ability to model and quantify brain activation patterns that pertain to natural neuromotor strategy of the upper extremities during functional task performance is critical to the development of therapeutic interventions such as neuroprosthetic devices. The mechanisms of information flow, activation sequence and patterns, and the interaction between anatomical regions of the brain that are specific to movement planning, intention and execution of voluntary upper extremity motor tasks were investigated here. This paper presents a novel method using symbolic dynamics (orbital decomposition) and nonlinear dynamic tools of entropy, self-organization and chaos to describe the underlying structure of activation shifts in regions of the brain that are involved with the cognitive aspects of functional upper extremity task performance. Several questions were addressed: (a) How is it possible to distinguish deterministic or causal patterns of activity in brain fMRI from those that are really random or non-contributory to the neuromotor control process? (b) Can the complexity of activation patterns over time be quantified? (c) What are the optimal ways of organizing fMRI data to preserve patterns of activation, activation levels, and extract meaningful temporal patterns as they evolve over time? Analysis was performed using data from a custom developed time resolved fMRI paradigm involving human subjects (N=18) who performed functional upper extremity motor tasks with varying time delays between the onset of intention and onset of actual movements. The results indicate that there is structure in the data that can be quantified through entropy and dimensional complexity metrics and statistical inference, and furthermore, orbital decomposition is sensitive in capturing the transition of states that correlate with the cognitive aspects of functional task performance.

Response Activation in Overlapping Tasks and the Response-Selection Bottleneck

ERIC Educational Resources Information Center

Schubert, Torsten; Fischer, Rico; Stelzel, Christine

2008-01-01

The authors investigated the impact of response activation on dual-task performance by presenting a subliminal prime before the stimulus in Task 2 (S2) of a psychological refractory period (PRP) task. Congruence between prime and S2 modulated the reaction times in Task 2 at short stimulus onset asynchrony despite a PRP effect. This Task 2…

One Step at a Time: Using Task Analyses to Teach Skills

ERIC Educational Resources Information Center

Snodgrass, Melinda R.; Meadan, Hedda; Ostrosky, Michaelene M.; Cheung, W. Catherine

2017-01-01

Task analyses are useful when teaching children how to complete tasks by breaking the tasks into small steps, particularly when children struggle to learn a skill during typical classroom instruction. We describe how to create a task analysis by identifying the steps a child needs to independently perform the task, how to assess what steps a child…

Speech responses and dual-task performance - Better time-sharing or asymmetric transfer?

NASA Technical Reports Server (NTRS)

Vidulich, Michael A.

1988-01-01

The value of speech controls in a dual-task experiment that also evaluated asymmetric transfer effects is considered. There was no evidence of asymmetric transfer in spite of significant effects supporting the advantage of mixing manual and speech responses. The data suggest that speech controls can be used to enhance performance in operational multiple-task environments.

An opportunity cost model of subjective effort and task performance

PubMed Central

Kurzban, Robert; Duckworth, Angela; Kable, Joseph W.; Myers, Justus

2013-01-01

Why does performing certain tasks cause the aversive experience of mental effort and concomitant deterioration in task performance? One explanation posits a physical resource that is depleted over time. We propose an alternate explanation that centers on mental representations of the costs and benefits associated with task performance. Specifically, certain computational mechanisms, especially those associated with executive function, can be deployed for only a limited number of simultaneous tasks at any given moment. Consequently, the deployment of these computational mechanisms carries an opportunity cost – that is, the next-best use to which these systems might be put. We argue that the phenomenology of effort can be understood as the felt output of these cost/benefit computations. In turn, the subjective experience of effort motivates reduced deployment of these computational mechanisms in the service of the present task. These opportunity cost representations, then, together with other cost/benefit calculations, determine effort expended and, everything else equal, result in performance reductions. In making our case for this position, we review alternate explanations both for the phenomenology of effort associated with these tasks and for performance reductions over time. Likewise, we review the broad range of relevant empirical results from across subdisciplines, especially psychology and neuroscience. We hope that our proposal will help to build links among the diverse fields that have been addressing similar questions from different perspectives, and we emphasize ways in which alternate models might be empirically distinguished. PMID:24304775

The impact of e-prescribing on prescriber and staff time in ambulatory care clinics: a time motion study.

PubMed

Hollingworth, William; Devine, Emily Beth; Hansen, Ryan N; Lawless, Nathan M; Comstock, Bryan A; Wilson-Norton, Jennifer L; Tharp, Kathleen L; Sullivan, Sean D

2007-01-01

Electronic prescribing has improved the quality and safety of care. One barrier preventing widespread adoption is the potential detrimental impact on workflow. We used time-motion techniques to compare prescribing times at three ambulatory care sites that used paper-based prescribing, desktop, or laptop e-prescribing. An observer timed all prescriber (n = 27) and staff (n = 42) tasks performed during a 4-hour period. At the sites with optional e-prescribing >75% of prescription-related events were performed electronically. Prescribers at e-prescribing sites spent less time writing, but time-savings were offset by increased computer tasks. After adjusting for site, prescriber and prescription type, e-prescribing tasks took marginally longer than hand written prescriptions (12.0 seconds; -1.6, 25.6 CI). Nursing staff at the e-prescribing sites spent longer on computer tasks (5.4 minutes/hour; 0.0, 10.7 CI). E-prescribing was not associated with an increase in combined computer and writing time for prescribers. If carefully implemented, e-prescribing will not greatly disrupt workflow.

Information Processing in Memory Tasks.

ERIC Educational Resources Information Center

Johnston, William A.

The intensity of information processing engendered in different phases of standard memory tasks was examined in six experiments. Processing intensity was conceptualized as system capacity consumed, and was measured via a divided-attention procedure in which subjects performed a memory task and a simple reaction-time (RT) task concurrently. The…

Planning Abilities in Bilingual and Monolingual Children: Role of Verbal Mediation.

PubMed

Gangopadhyay, Ishanti; McDonald, Margarethe; Ellis Weismer, Susan; Kaushanskaya, Margarita

2018-01-01

We examined the role of verbal mediation in planning performance of English-Spanish-speaking bilingual children and monolingual English-speaking children, between the ages of 9 and 12 years. To measure planning, children were administered the Tower of London (ToL) task. In a dual-task paradigm, children completed ToL problems under three conditions: with no secondary task (baseline), with articulatory suppression, and with non-verbal motor suppression. Analyses revealed generally shorter planning times for bilinguals than monolinguals but both groups performed similarly on number of moves and execution times. Additionally, bilingual children were more efficient at planning throughout the duration of the task while monolingual children showed significant gains with more practice. Children's planning times under articulatory suppression were significantly shorter than under motor suppression as well as the baseline condition, and there was no difference in planning times between monolingual and bilingual children during articulatory suppression. These results demonstrate that bilingualism influences performance on a complex EF measure like planning, and that these effects are not related to verbal mediation.

Prospective memory in first-degree relatives of patients with schizophrenia.

PubMed

Saleem, Saima; Kumar, Devvarta; Venkatasubramanian, Ganesan

2017-12-07

Among various cognitive impairments in schizophrenia, prospective memory (ProM) deficit is unequivocally established. However, there is a paucity of research examining whether ProM impairment can be considered a cognitive endophenotypic marker in schizophrenia. An important step toward this is to assess the status of ProM in first-degree relatives (FDRs) of patients with schizophrenia. Keeping this in view, present study has been conducted to assess event- and time-based ProM in FDRs of patients with schizophrenia. Twenty patients with schizophrenia, 20 FDRs of these patients, and 20 nonpsychiatric (healthy) controls were administered event- and time-based ProM tasks. Findings show that the FDRs had poorer performance on event-based ProM task in comparison to healthy controls. On time-based task, though the FDRs performed poorly in comparison to healthy controls the difference was statistically non-significant. The patient group performed poorer than healthy controls on both event- and time-based tasks. Findings of the present study indicate that the FDRs of patients with schizophrenia exhibit ProM impairment, though to a lesser degree than the patients with schizophrenia.

Planning Abilities in Bilingual and Monolingual Children: Role of Verbal Mediation

PubMed Central

Gangopadhyay, Ishanti; McDonald, Margarethe; Ellis Weismer, Susan; Kaushanskaya, Margarita

2018-01-01

We examined the role of verbal mediation in planning performance of English–Spanish-speaking bilingual children and monolingual English-speaking children, between the ages of 9 and 12 years. To measure planning, children were administered the Tower of London (ToL) task. In a dual-task paradigm, children completed ToL problems under three conditions: with no secondary task (baseline), with articulatory suppression, and with non-verbal motor suppression. Analyses revealed generally shorter planning times for bilinguals than monolinguals but both groups performed similarly on number of moves and execution times. Additionally, bilingual children were more efficient at planning throughout the duration of the task while monolingual children showed significant gains with more practice. Children’s planning times under articulatory suppression were significantly shorter than under motor suppression as well as the baseline condition, and there was no difference in planning times between monolingual and bilingual children during articulatory suppression. These results demonstrate that bilingualism influences performance on a complex EF measure like planning, and that these effects are not related to verbal mediation. PMID:29593620

Attentional Predictors of 5-month-olds' Performance on a Looking A-not-B Task.

PubMed

Marcovitch, Stuart; Clearfield, Melissa W; Swingler, Margaret; Calkins, Susan D; Bell, Martha Ann

2016-01-01

In the first year of life, the ability to search for hidden objects is an indicator of object permanence and, when multiple locations are involved, executive function (i.e. inhibition, cognitive flexibility and working memory). The current study was designed to examine attentional predictors of search in 5-month-old infants (as measured by the looking A-not-B task), and whether levels of maternal education moderated the effect of the predictors. Specifically, in a separate task, the infants were shown a unique puppet, and we measured the percentage of time attending to the puppet, as well as the length of the longest look (i.e., peak fixation) directed towards the puppet. Across the entire sample ( N =390), the percentage of time attending to the puppet was positively related to performance on the visual A-not-B task. However, for infants whose mothers had not completed college, having a shorter peak looking time (after controlling for percentage of time) was also a predictor of visual A-not-B performance. The role of attention, peak fixation and maternal education in visual search is discussed.

Controlling an avatar by thought using real-time fMRI

NASA Astrophysics Data System (ADS)

Cohen, Ori; Koppel, Moshe; Malach, Rafael; Friedman, Doron

2014-06-01

Objective. We have developed a brain-computer interface (BCI) system based on real-time functional magnetic resonance imaging (fMRI) with virtual reality feedback. The advantage of fMRI is the relatively high spatial resolution and the coverage of the whole brain; thus we expect that it may be used to explore novel BCI strategies, based on new types of mental activities. However, fMRI suffers from a low temporal resolution and an inherent delay, since it is based on a hemodynamic response rather than electrical signals. Thus, our objective in this paper was to explore whether subjects could perform a BCI task in a virtual environment using our system, and how their performance was affected by the delay. Approach. The subjects controlled an avatar by left-hand, right-hand and leg motion or imagery. The BCI classification is based on locating the regions of interest (ROIs) related with each of the motor classes, and selecting the ROI with maximum average values online. The subjects performed a cue-based task and a free-choice task, and the analysis includes evaluation of the performance as well as subjective reports. Main results. Six subjects performed the task with high accuracy when allowed to move their fingers and toes, and three subjects achieved high accuracy using imagery alone. In the cue-based task the accuracy was highest 8-12 s after the trigger, whereas in the free-choice task the subjects performed best when the feedback was provided 6 s after the trigger. Significance. We show that subjects are able to perform a navigation task in a virtual environment using an fMRI-based BCI, despite the hemodynamic delay. The same approach can be extended to other mental tasks and other brain areas.

The Neurocognitive Basis for Impaired Dual-Task Performance in Senior Fallers.

PubMed

Nagamatsu, Lindsay S; Hsu, C Liang; Voss, Michelle W; Chan, Alison; Bolandzadeh, Niousha; Handy, Todd C; Graf, Peter; Beattie, B Lynn; Liu-Ambrose, Teresa

2016-01-01

Falls are a major health-care concern, and while dual-task performance is widely recognized as being impaired in those at-risk for falls, the underlying neurocognitive mechanisms remain unknown. A better understanding of the underlying mechanisms could lead to the refinement and development of behavioral, cognitive, or neuropharmacological interventions for falls prevention. Therefore, we conducted a cross-sectional study with community-dwelling older adults aged 70-80 years with a history of falls (i.e., two or more falls in the past 12 months) or no history of falls (i.e., zero falls in the past 12 months); n = 28 per group. We compared functional activation during cognitive-based dual-task performance between fallers and non-fallers using functional magnetic resonance imaging (fMRI). Executive cognitive functioning was assessed via Stroop, Trail Making, and Digit Span. Mobility was assessed via the Timed Up and Go test (TUG). We found that non-fallers exhibited significantly greater functional activation compared with fallers during dual-task performance in key regions responsible for resolving dual-task interference, including precentral, postcentral, and lingual gyri. Further, we report slower reaction times during dual-task performance in fallers and significant correlations between level of functional activation and independent measures of executive cognitive functioning and mobility. Our study is the first neuroimaging study to examine dual-task performance in fallers, and supports the notion that fallers have reduced functional brain activation compared with non-fallers. Given that dual-task performance-and the underlying neural concomitants-appears to be malleable with relevant training, our study serves as a launching point for promising strategies to reduce falls in the future.

Identification of Time-Varying Pilot Control Behavior in Multi-Axis Control Tasks

NASA Technical Reports Server (NTRS)

Zaal, Peter M. T.; Sweet, Barbara T.

2012-01-01

Recent developments in fly-by-wire control architectures for rotorcraft have introduced new interest in the identification of time-varying pilot control behavior in multi-axis control tasks. In this paper a maximum likelihood estimation method is used to estimate the parameters of a pilot model with time-dependent sigmoid functions to characterize time-varying human control behavior. An experiment was performed by 9 general aviation pilots who had to perform a simultaneous roll and pitch control task with time-varying aircraft dynamics. In 8 different conditions, the axis containing the time-varying dynamics and the growth factor of the dynamics were varied, allowing for an analysis of the performance of the estimation method when estimating time-dependent parameter functions. In addition, a detailed analysis of pilots adaptation to the time-varying aircraft dynamics in both the roll and pitch axes could be performed. Pilot control behavior in both axes was significantly affected by the time-varying aircraft dynamics in roll and pitch, and by the growth factor. The main effect was found in the axis that contained the time-varying dynamics. However, pilot control behavior also changed over time in the axis not containing the time-varying aircraft dynamics. This indicates that some cross coupling exists in the perception and control processes between the roll and pitch axes.

Program Predicts Time Courses of Human/Computer Interactions

NASA Technical Reports Server (NTRS)

Vera, Alonso; Howes, Andrew

2005-01-01

CPM X is a computer program that predicts sequences of, and amounts of time taken by, routine actions performed by a skilled person performing a task. Unlike programs that simulate the interaction of the person with the task environment, CPM X predicts the time course of events as consequences of encoded constraints on human behavior. The constraints determine which cognitive and environmental processes can occur simultaneously and which have sequential dependencies. The input to CPM X comprises (1) a description of a task and strategy in a hierarchical description language and (2) a description of architectural constraints in the form of rules governing interactions of fundamental cognitive, perceptual, and motor operations. The output of CPM X is a Program Evaluation Review Technique (PERT) chart that presents a schedule of predicted cognitive, motor, and perceptual operators interacting with a task environment. The CPM X program allows direct, a priori prediction of skilled user performance on complex human-machine systems, providing a way to assess critical interfaces before they are deployed in mission contexts.

Real-time measurement of mental workload: A feasibility study

NASA Technical Reports Server (NTRS)

Kramer, Arthur; Humphrey, Darryl; Sirevaag, Erik; Mecklinger, Axel

1990-01-01

The primary goal of the study was to explore the utility of event-related brain potentials (ERP) as real-time measures of workload. To this end, subjects performed two different tasks both separately and together. One task required that subjects monitor a bank of constantly changing gauges and detect critical deviations. Difficulty was varied by changing the predictability of the gauges. The second task was mental arithmetic. Difficulty was varied by requiring subjects to perform operations on either two or three columns of numbers. Two conditions that could easily be distinguished on the basis of performance measures were selected for the real-time evaluation of ERPs. A bootstrapping approach was adopted in which one thousand samples of n trials (n = 1, 3, 5 ...65) were classified using several measures of P300 and Slow Wave amplitude. Classification accuracies of 85 percent were achieved with 25 trials. Results are discussed in terms of potential enhancements for real-time recording.

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

PubMed

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

2017-11-01

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

Effects of Divided Attention at Retrieval on Conceptual Implicit Memory

PubMed Central

Prull, Matthew W.; Lawless, Courtney; Marshall, Helen M.; Sherman, Annabella T. K.

2016-01-01

This study investigated whether conceptual implicit memory is sensitive to process-specific interference at the time of retrieval. Participants performed the implicit memory test of category exemplar generation (CEG; Experiments 1 and 3), or the matched explicit memory test of category-cued recall (Experiment 2), both of which are conceptually driven memory tasks, under one of two divided attention (DA) conditions in which participants simultaneously performed a distracting task. The distracting task was either syllable judgments (dissimilar processes), or semantic judgments (similar processes) on unrelated words. Compared to full attention (FA) in which no distracting task was performed, DA had no effect on CEG priming overall, but reduced category-cued recall similarly regardless of distractor task. Analyses of distractor task performance also revealed differences between implicit and explicit memory retrieval. The evidence suggests that, whereas explicit memory retrieval requires attentional resources and is disrupted by semantic and phonological distracting tasks, conceptual implicit memory is automatic and unaffected even when distractor and memory tasks involve similar processes. PMID:26834678

Effects of Divided Attention at Retrieval on Conceptual Implicit Memory.

PubMed

Prull, Matthew W; Lawless, Courtney; Marshall, Helen M; Sherman, Annabella T K

2016-01-01

This study investigated whether conceptual implicit memory is sensitive to process-specific interference at the time of retrieval. Participants performed the implicit memory test of category exemplar generation (CEG; Experiments 1 and 3), or the matched explicit memory test of category-cued recall (Experiment 2), both of which are conceptually driven memory tasks, under one of two divided attention (DA) conditions in which participants simultaneously performed a distracting task. The distracting task was either syllable judgments (dissimilar processes), or semantic judgments (similar processes) on unrelated words. Compared to full attention (FA) in which no distracting task was performed, DA had no effect on CEG priming overall, but reduced category-cued recall similarly regardless of distractor task. Analyses of distractor task performance also revealed differences between implicit and explicit memory retrieval. The evidence suggests that, whereas explicit memory retrieval requires attentional resources and is disrupted by semantic and phonological distracting tasks, conceptual implicit memory is automatic and unaffected even when distractor and memory tasks involve similar processes.

Measuring the Performance of Attention Networks with the Dalhousie Computerized Attention Battery (DalCAB): Methodology and Reliability in Healthy Adults.

PubMed

Jones, Stephanie A H; Butler, Beverly C; Kintzel, Franziska; Johnson, Anne; Klein, Raymond M; Eskes, Gail A

2016-01-01

Attention is an important, multifaceted cognitive domain that has been linked to three distinct, yet interacting, networks: alerting, orienting, and executive control. The measurement of attention and deficits of attention within these networks is critical to the assessment of many neurological and psychiatric conditions in both research and clinical settings. The Dalhousie Computerized Attention Battery (DalCAB) was created to assess attentional functions related to the three attention networks using a range of tasks including: simple reaction time, go/no-go, choice reaction time, dual task, flanker, item and location working memory, and visual search. The current study provides preliminary normative data, test-retest reliability (intraclass correlations) and practice effects in DalCAB performance 24-h after baseline for healthy young adults (n = 96, 18-31 years). Performance on the DalCAB tasks demonstrated Good to Very Good test-retest reliability for mean reaction time, while accuracy and difference measures (e.g., switch costs, interference effects, and working memory load effects) were most reliable for tasks that require more extensive cognitive processing (e.g., choice reaction time, flanker, dual task, and conjunction search). Practice effects were common and pronounced at the 24-h interval. In addition, performance related to specific within-task parameters of the DalCAB sub-tests provides preliminary support for future formal assessment of the convergent validity of our interpretation of the DalCAB as a potential clinical and research assessment tool for measuring aspects of attention related to the alerting, orienting, and executive control networks.

Testing Task Schedulers on Linux System

NASA Astrophysics Data System (ADS)

Jelenković, Leonardo; Groš, Stjepan; Jakobović, Domagoj

Testing task schedulers on Linux operating system proves to be a challenging task. There are two main problems. The first one is to identify which properties of the scheduler to test. The second problem is how to perform it, e.g., which API to use that is sufficiently precise and in the same time supported on most platforms. This paper discusses the problems in realizing test framework for testing task schedulers and presents one potential solution. Observed behavior of the scheduler is the one used for “normal” task scheduling (SCHED_OTHER), unlike one used for real-time tasks (SCHED_FIFO, SCHED_RR).

A single robotic session that guides or increases movement error in survivors post-chronic stroke: which intervention is best to boost the learning of a timing task?

PubMed

Bouchard, Amy E; Corriveau, Hélène; Milot, Marie-Hélène

2017-08-01

Timing deficits can have a negative impact on the lives of survivors post-chronic stroke. Studies evaluating ways to improve timing post stroke are scarce. The goal of the study was to evaluate the impact of a single session of haptic guidance (HG) and error amplification (EA) robotic training interventions on the improvement of post-stroke timing accuracy. Thirty-four survivors post-chronic stroke were randomly assigned to HG or EA. Participants played a computerized pinball-like game with their affected hand positioned in a robot that either helped them perform better (HG) or worse (EA) during the task. A baseline and retention phase preceded and followed HG and EA, respectively, in order to assess their efficiency at improving absolute timing errors. The impact of the side of the stroke lesion on the participants' performance during the timing task was also explored for each training group. An improvement in timing performance was only noted following HG (8.9 ± 4.9 ms versus 7.8 ± 5.3 ms, p = 0.032). Moreover, for the EA group only, participants with a left-sided stroke lesion showed a worsening in performance as compared to those with a right-sided stroke lesion (p = 0.001). Helping survivors post-chronic stroke perform a timing-based task is beneficial to learning. Future studies should explore longer and more frequent HG training sessions in order to further promote post stroke motor recovery. Implications for Rehabilitation Timing is crucial for the accomplishment of daily tasks. The number of studies dedicated to improving timing is scarce in the literature, even though timing deficits are common post stroke. This innovative study evaluated the impact of a single session of haptic guidance-HG and error amplification-EA robotic training interventions on improvements in timing accuracy among survivors post chronic stroke. HG robotic training improves timing accuracy more than EA among survivors post chronic stroke.

Combining of ETHOS Operating Ergonomic Platform, Three-dimensional Laparoscopic Camera, and Radius Surgical System Manipulators Improves Ergonomy in Urologic Laparoscopy: Comparison with Conventional Laparoscopy and da Vinci in a Pelvi Trainer.

PubMed

Tokas, Theodoros; Gözen, Ali Serdar; Avgeris, Margaritis; Tschada, Alexandra; Fiedler, Marcel; Klein, Jan; Rassweiler, Jens

2017-10-01

Posture, vision, and instrumentation limitations are the main predicaments of conventional laparoscopy. To combine the ETHOS surgical chair, the three-dimensional laparoscope, and the Radius Surgical System manipulators, and compare the system with conventional laparoscopy and da Vinci in terms of task completion times and discomfort. Fifteen trainees performed the three main laparoscopic suturing tasks of the Heilbronn training program (IV: simulation of dorsal venous complex suturing; V: circular suturing of tubular structure; and VI: urethrovesical anastomosis) in a pelvi trainer. The tasks were performed conventionally, utilizing the three devices, and robotically. Task completion times were recorded and the surgeon discomfort was evaluated using questionnaires. Task completion times were compared using nonparametric Wilcoxon signed rank test and ergonomic scores were compared using Pearson chi-square test. The use of the full laparoscopic set (ETHOS chair, three-dimensional laparoscopic camera, Radius Surgical System needle holders), resulted in a significant improvement of the completion time of the three tested tasks compared with conventional laparoscopy (p<0.001) and similar to da Vinci surgery. After completing Tasks IV, V, and VI conventionally, 12 (80%), 13 (86.7%), and 13 (86.7%) of the 15 trainees, respectively, reported heavy total discomfort. The full laparoscopic system nullified heavy discomfort for Tasks IV and V and minimized it (6.7%) for the most demanding Task VI. Especially for Task VI, all trainees gained benefit, by using the system, in terms of task completion times and discomfort. The limited trainee robotic experience and the questionnaire subjectivity could be a potential limitation. The ergonomic laparoscopic system offers significantly improved task completion times and ergonomy than conventional laparoscopy. Furthermore, it demonstrates comparable results to robotic surgery. The study was conducted in a pelvi trainer and no patients were recruited. Copyright © 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Is a Responsive Default Mode Network Required for Successful Working Memory Task Performance?

PubMed Central

Čeko, Marta; Gracely, John L.; Fitzcharles, Mary-Ann; Seminowicz, David A.; Schweinhardt, Petra

2015-01-01

In studies of cognitive processing using tasks with externally directed attention, regions showing increased (external-task-positive) and decreased or “negative” [default-mode network (DMN)] fMRI responses during task performance are dynamically responsive to increasing task difficulty. Responsiveness (modulation of fMRI signal by increasing load) has been linked directly to successful cognitive task performance in external-task-positive regions but not in DMN regions. To investigate whether a responsive DMN is required for successful cognitive performance, we compared healthy human subjects (n = 23) with individuals shown to have decreased DMN engagement (chronic pain patients, n = 28). Subjects performed a multilevel working-memory task (N-back) during fMRI. If a responsive DMN is required for successful performance, patients having reduced DMN responsiveness should show worsened performance; if performance is not reduced, their brains should show compensatory activation in external-task-positive regions or elsewhere. All subjects showed decreased accuracy and increased reaction times with increasing task level, with no significant group differences on either measure at any level. Patients had significantly reduced negative fMRI response (deactivation) of DMN regions (posterior cingulate/precuneus, medial prefrontal cortex). Controls showed expected modulation of DMN deactivation with increasing task difficulty. Patients showed significantly reduced modulation of DMN deactivation by task difficulty, despite their successful task performance. We found no evidence of compensatory neural recruitment in external-task-positive regions or elsewhere. Individual responsiveness of the external-task-positive ventrolateral prefrontal cortex, but not of DMN regions, correlated with task accuracy. These findings suggest that a responsive DMN may not be required for successful cognitive performance; a responsive external-task-positive network may be sufficient. SIGNIFICANCE STATEMENT We studied the relationship between responsiveness of the brain to increasing task demand and successful cognitive performance, using chronic pain patients as a probe. fMRI working memory studies show that two main cognitive networks [“external-task positive” and “default-mode network” (DMN)] are responsive to increasing task difficulty. The responsiveness of both of these brain networks is suggested to be required for successful task performance. The responsiveness of external-task-positive regions has been linked directly to successful cognitive task performance, as we also show here. However, pain patients show decreased engagement and responsiveness of the DMN but can perform a working memory task as well as healthy subjects, without demonstrable compensatory neural recruitment. Therefore, a responsive DMN might not be needed for successful cognitive performance. PMID:26290236

Is a Responsive Default Mode Network Required for Successful Working Memory Task Performance?

PubMed

Čeko, Marta; Gracely, John L; Fitzcharles, Mary-Ann; Seminowicz, David A; Schweinhardt, Petra; Bushnell, M Catherine

2015-08-19

In studies of cognitive processing using tasks with externally directed attention, regions showing increased (external-task-positive) and decreased or "negative" [default-mode network (DMN)] fMRI responses during task performance are dynamically responsive to increasing task difficulty. Responsiveness (modulation of fMRI signal by increasing load) has been linked directly to successful cognitive task performance in external-task-positive regions but not in DMN regions. To investigate whether a responsive DMN is required for successful cognitive performance, we compared healthy human subjects (n = 23) with individuals shown to have decreased DMN engagement (chronic pain patients, n = 28). Subjects performed a multilevel working-memory task (N-back) during fMRI. If a responsive DMN is required for successful performance, patients having reduced DMN responsiveness should show worsened performance; if performance is not reduced, their brains should show compensatory activation in external-task-positive regions or elsewhere. All subjects showed decreased accuracy and increased reaction times with increasing task level, with no significant group differences on either measure at any level. Patients had significantly reduced negative fMRI response (deactivation) of DMN regions (posterior cingulate/precuneus, medial prefrontal cortex). Controls showed expected modulation of DMN deactivation with increasing task difficulty. Patients showed significantly reduced modulation of DMN deactivation by task difficulty, despite their successful task performance. We found no evidence of compensatory neural recruitment in external-task-positive regions or elsewhere. Individual responsiveness of the external-task-positive ventrolateral prefrontal cortex, but not of DMN regions, correlated with task accuracy. These findings suggest that a responsive DMN may not be required for successful cognitive performance; a responsive external-task-positive network may be sufficient. We studied the relationship between responsiveness of the brain to increasing task demand and successful cognitive performance, using chronic pain patients as a probe. fMRI working memory studies show that two main cognitive networks ["external-task positive" and "default-mode network" (DMN)] are responsive to increasing task difficulty. The responsiveness of both of these brain networks is suggested to be required for successful task performance. The responsiveness of external-task-positive regions has been linked directly to successful cognitive task performance, as we also show here. However, pain patients show decreased engagement and responsiveness of the DMN but can perform a working memory task as well as healthy subjects, without demonstrable compensatory neural recruitment. Therefore, a responsive DMN might not be needed for successful cognitive performance. Copyright © 2015 the authors 0270-6474/15/3511596-11$15.00/0.

Approximate number sense, symbolic number processing, or number-space mappings: what underlies mathematics achievement?

PubMed

Sasanguie, Delphine; Göbel, Silke M; Moll, Kristina; Smets, Karolien; Reynvoet, Bert

2013-03-01

In this study, the performance of typically developing 6- to 8-year-old children on an approximate number discrimination task, a symbolic comparison task, and a symbolic and nonsymbolic number line estimation task was examined. For the first time, children's performances on these basic cognitive number processing tasks were explicitly contrasted to investigate which of them is the best predictor of their future mathematical abilities. Math achievement was measured with a timed arithmetic test and with a general curriculum-based math test to address the additional question of whether the predictive association between the basic numerical abilities and mathematics achievement is dependent on which math test is used. Results revealed that performance on both mathematics achievement tests was best predicted by how well childrencompared digits. In addition, an association between performance on the symbolic number line estimation task and math achievement scores for the general curriculum-based math test measuring a broader spectrum of skills was found. Together, these results emphasize the importance of learning experiences with symbols for later math abilities. Copyright © 2012 Elsevier Inc. All rights reserved.

Making sense of theory of mind and paranoia: the psychometric properties and reasoning requirements of a false belief sequencing task.

PubMed

Corcoran, Rhiannon; Bentall, Richard P; Rowse, Georgina; Moore, Rosanne; Cummins, Sinead; Blackwood, Nigel; Howard, Robert; Shryane, Nick M

2011-11-01

INTRODUCTION. This study used Item-Response Theory (IRT) to model the psychometric properties of a false belief picture sequencing task. Consistent with the mental time travel hypothesis of paranoia, we anticipated that performance on this deductive theory of mind (ToM) task would not be associated with the presence of persecutory delusions but would be related to other clinical, cognitive, and demographic factors. METHOD. A large (N=237) and diverse clinical and nonclinical sample differing in levels of depression and paranoid ideation performed 2 ToM tasks: the false belief sequencing task and a ToM stories task that was used to assess the validity of the false belief sequencing task as a measure of ToM. RESULTS. A unidimensional IRT model was found to fit the data well. Latent ToM ability as measured by the false belief sequencing task was negatively related with age and positively with IQ. In contrast to the ToM stories measure, there was no association between clinical diagnosis or symptoms and false belief picture sequencing after controlling for age and IQ. CONCLUSIONS. In line with mental time travel hypothesis of paranoia (Corcoran, 2010 ), performance on this deductive nonverbal ToM task is not related to the presence of paranoid symptoms. This measure is best suited for assessing ToM functioning where participants' performance falls just short of the average latent ToM ability. Furthermore, it is sensitive to the effects of increasing age and decreasing IQ.

CAMS as a tool for human factors research in spaceflight

NASA Astrophysics Data System (ADS)

Sauer, Juergen

2004-01-01

The paper reviews a number of research studies that were carried out with a PC-based task environment called Cabin Air Management System (CAMS) simulating the operation of a spacecraft's life support system. As CAMS was a multiple task environment, it allowed the measurement of performance at different levels. Four task components of different priority were embedded in the task environment: diagnosis and repair of system faults, maintaining atmospheric parameters in a safe state, acknowledgement of system alarms (reaction time), and keeping a record of critical system resources (prospective memory). Furthermore, the task environment permitted the examination of different task management strategies and changes in crew member state (fatigue, anxiety, mental effort). A major goal of the research programme was to examine how crew members adapted to various forms of sub-optimal working conditions, such as isolation and confinement, sleep deprivation and noise. None of the studies provided evidence for decrements in primary task performance. However, the results showed a number of adaptive responses of crew members to adjust to the different sub-optimal working conditions. There was evidence for adjustments in information sampling strategies (usually reductions in sampling frequency) as a result of unfavourable working conditions. The results also showed selected decrements in secondary task performance. Prospective memory seemed to be somewhat more vulnerable to sub-optimal working conditions than performance on the reaction time task. Finally, suggestions are made for future research with the CAMS environment.

Evaluation of Augmented Reality Feedback in Surgical Training Environment.

PubMed

Zahiri, Mohsen; Nelson, Carl A; Oleynikov, Dmitry; Siu, Ka-Chun

2018-02-01

Providing computer-based laparoscopic surgical training has several advantages that enhance the training process. Self-evaluation and real-time performance feedback are 2 of these advantages, which avoid dependency of trainees on expert feedback. The goal of this study was to investigate the use of a visual time indicator as real-time feedback correlated with the laparoscopic surgical training. Twenty novices participated in this study working with (and without) different presentations of time indicators. They performed a standard peg transfer task, and their completion times and muscle activity were recorded and compared. Also of interest was whether the use of this type of feedback induced any side effect in terms of motivation or muscle fatigue. Of the 20 participants, 15 (75%) preferred using a time indicator in the training process rather than having no feedback. However, time to task completion showed no significant difference in performance with the time indicator; furthermore, no significant differences in muscle activity or muscle fatigue were detected with/without time feedback. The absence of significant difference between task performance with/without time feedback shows that using visual real-time feedback can be included in surgical training based on user preference. Trainees may benefit from this type of feedback in the form of increased motivation. The extent to which this can influence training frequency leading to performance improvement is a question for further study.

A Modified Distributed Bees Algorithm for Multi-Sensor Task Allocation.

PubMed

Tkach, Itshak; Jevtić, Aleksandar; Nof, Shimon Y; Edan, Yael

2018-03-02

Multi-sensor systems can play an important role in monitoring tasks and detecting targets. However, real-time allocation of heterogeneous sensors to dynamic targets/tasks that are unknown a priori in their locations and priorities is a challenge. This paper presents a Modified Distributed Bees Algorithm (MDBA) that is developed to allocate stationary heterogeneous sensors to upcoming unknown tasks using a decentralized, swarm intelligence approach to minimize the task detection times. Sensors are allocated to tasks based on sensors' performance, tasks' priorities, and the distances of the sensors from the locations where the tasks are being executed. The algorithm was compared to a Distributed Bees Algorithm (DBA), a Bees System, and two common multi-sensor algorithms, market-based and greedy-based algorithms, which were fitted for the specific task. Simulation analyses revealed that MDBA achieved statistically significant improved performance by 7% with respect to DBA as the second-best algorithm, and by 19% with respect to Greedy algorithm, which was the worst, thus indicating its fitness to provide solutions for heterogeneous multi-sensor systems.

Context matters: Social cognition task performance in psychometric schizotypes.

PubMed

Pflum, Madeline J; Gooding, Diane C

2018-06-01

Patients with schizophrenia show performance deficits on tasks requiring empathy-related social cognition. The extent to which empathy impairments are observed in psychometric schizotypy is unclear. We compared accuracy and reaction time in three groups of individuals characterized by positive schizotypy (n = 79), negative schizotypy (n = 123), or low schizotypy group (n = 137). On a social cognition task that provided context, namely, the Emotion Perspective Taking Task, the positive schizotypes showed poorer performance than the negative schizotypy and control groups. These results suggest that some schizotypes differ in their ability to make use of context (e.g., social cues from the environment) to affect their social cognitive performance. However, on the Affective Responsiveness Task, in which no context was given, both groups of psychometric schizotypes displayed lower performance than the controls. These findings highlight the importance of assessing multiple groups of schizotypes as well as the value of including several social cognition tasks in order to reveal relative performance deficits. Copyright © 2018 Elsevier B.V. All rights reserved.

Taking a Stand: The Effects of Standing Desks on Task Performance and Engagement

PubMed Central

Tomiyama, A. Janet; Ward, Andrew

2017-01-01

Time spent sitting is associated with negative health outcomes, motivating some individuals to adopt standing desk workstations. This study represents the first investigation of the effects of standing desk use on reading comprehension and creativity. In a counterbalanced, within-subjects design, 96 participants completed reading comprehension and creativity tasks while both sitting and standing. Participants self-reported their mood during the tasks and also responded to measures of expended effort and task difficulty. In addition, participants indicated whether they expected that they would perform better on work-relevant tasks while sitting or standing. Despite participants’ beliefs that they would perform worse on most tasks while standing, body position did not affect reading comprehension or creativity performance, nor did it affect perceptions of effort or difficulty. Mood was also unaffected by position, with a few exceptions: Participants exhibited greater task engagement (i.e., interest, enthusiasm, and alertness) and less comfort while standing rather than sitting. In sum, performance and psychological experience as related to task completion were nearly entirely uninfluenced by acute (~30-min) standing desk use. PMID:28825655

Repeating a Monologue under Increasing Time Pressure: Effects on Fluency, Complexity, and Accuracy

ERIC Educational Resources Information Center

Thai, Chau; Boers, Frank

2016-01-01

Studies have shown that learners' task performance improves when they have the opportunity to repeat the task. Conditions for task repetition vary, however. In the 4/3/2 activity, learners repeat a monologue under increasing time pressure. The purpose is to foster fluency, but it has been suggested in the literature that it also benefits other…

Muscle activity, time to fatigue, and maximum task duration at different levels of production standard time

PubMed Central

Nur, Nurhayati Mohd; Dawal, Siti Zawiah Md; Dahari, Mahidzal; Sanusi, Junedah

2015-01-01

[Purpose] This study investigated the variations in muscle fatigue, time to fatigue, and maximum task duration at different levels of production standard time. [Methods] Twenty subjects performed repetitive tasks at three different levels of production standard time corresponding to “normal”, “hard” and “very hard”. Surface electromyography was used to measure the muscle activity. [Results] The results showed that muscle activity was significantly affected by the production standard time level. Muscle activity increased twice in percentage as the production standard time shifted from hard to very hard (6.9% vs. 12.9%). The muscle activity increased over time, indicating muscle fatigue. The muscle fatigue rate increased for the harder production standard time (Hard: 0.105; Very hard: 0.115), which indicated the associated higher risk of work-related musculoskeletal disorders. Muscle fatigue was also found to occur earlier for hard and very hard production standard times. [Conclusion] It is recommended that the maximum task duration should not exceed 5.6, 2.9, and 2.2 hours for normal, hard, and very hard production standard times, respectively, in order to maintain work performance and minimize the risk of work-related musculoskeletal disorders. PMID:26311974

Method and system for benchmarking computers

DOEpatents

Gustafson, John L.

1993-09-14

A testing system and method for benchmarking computer systems. The system includes a store containing a scalable set of tasks to be performed to produce a solution in ever-increasing degrees of resolution as a larger number of the tasks are performed. A timing and control module allots to each computer a fixed benchmarking interval in which to perform the stored tasks. Means are provided for determining, after completion of the benchmarking interval, the degree of progress through the scalable set of tasks and for producing a benchmarking rating relating to the degree of progress for each computer.

Individual strategy ratings improve the control for task difficulty effects in arithmetic problem solving paradigms.

PubMed

Tschentscher, Nadja; Hauk, Olaf

2015-01-01

Mental arithmetic is a powerful paradigm to study problem solving using neuroimaging methods. However, the evaluation of task complexity varies significantly across neuroimaging studies. Most studies have parameterized task complexity by objective features such as the number size. Only a few studies used subjective rating procedures. In fMRI, we provided evidence that strategy self-reports control better for task complexity across arithmetic conditions than objective features (Tschentscher and Hauk, 2014). Here, we analyzed the relative predictive value of self-reported strategies and objective features for performance in addition and multiplication tasks, by using a paradigm designed for neuroimaging research. We found a superiority of strategy ratings as predictor of performance above objective features. In a Principal Component Analysis on reaction times, the first component explained over 90 percent of variance and factor loadings reflected percentages of self-reported strategies well. In multiple regression analyses on reaction times, self-reported strategies performed equally well or better than objective features, depending on the operation type. A Receiver Operating Characteristic (ROC) analysis confirmed this result. Reaction times classified task complexity better when defined by individual ratings. This suggests that participants' strategy ratings are reliable predictors of arithmetic complexity and should be taken into account in neuroimaging research.

Individual strategy ratings improve the control for task difficulty effects in arithmetic problem solving paradigms

PubMed Central

Tschentscher, Nadja; Hauk, Olaf

2015-01-01

Mental arithmetic is a powerful paradigm to study problem solving using neuroimaging methods. However, the evaluation of task complexity varies significantly across neuroimaging studies. Most studies have parameterized task complexity by objective features such as the number size. Only a few studies used subjective rating procedures. In fMRI, we provided evidence that strategy self-reports control better for task complexity across arithmetic conditions than objective features (Tschentscher and Hauk, 2014). Here, we analyzed the relative predictive value of self-reported strategies and objective features for performance in addition and multiplication tasks, by using a paradigm designed for neuroimaging research. We found a superiority of strategy ratings as predictor of performance above objective features. In a Principal Component Analysis on reaction times, the first component explained over 90 percent of variance and factor loadings reflected percentages of self-reported strategies well. In multiple regression analyses on reaction times, self-reported strategies performed equally well or better than objective features, depending on the operation type. A Receiver Operating Characteristic (ROC) analysis confirmed this result. Reaction times classified task complexity better when defined by individual ratings. This suggests that participants’ strategy ratings are reliable predictors of arithmetic complexity and should be taken into account in neuroimaging research. PMID:26321997

An analysis of the suitability of a low-cost eye tracker for assessing the cognitive load of drivers.

PubMed

Čegovnik, Tomaž; Stojmenova, Kristina; Jakus, Grega; Sodnik, Jaka

2018-04-01

This paper presents a driving simulator study in which we investigated whether the Eye Tribe eye tracker (ET) is capable of assessing changes in the cognitive load of drivers through oculography and pupillometry. In the study, participants were asked to drive a simulated vehicle and simultaneously perform a set of secondary tasks with different cognitive complexity levels. We measured changes in eye properties, such as the pupil size, blink rate and fixation time. We also performed a measurement with a Detection Response Task (DRT) to validate the results and to prove a steady increase of cognitive load with increasing secondary task difficulty. The results showed that the ET precisely recognizes an increasing pupil diameter with increasing secondary task difficulty. In addition, the ET shows increasing blink rates, decreasing fixation time and narrowing of the attention field with increasing secondary task difficulty. The results were validated with the DRT method and the secondary task performance. We conclude that the Eye Tribe ET is a suitable device for assessing a driver's cognitive load. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transcranial direct current stimulation (tDCS) to the supplementary motor area (SMA) influences performance on motor tasks.

PubMed

Hupfeld, K E; Ketcham, C J; Schneider, H D

2017-03-01

The supplementary motor area (SMA) is believed to be highly involved in the planning and execution of both simple and complex motor tasks. This study aimed to examine the role of the SMA in planning the movements required to complete reaction time, balance, and pegboard tasks using anodal transcranial direct current stimulation (tDCS), which passes a weak electrical current between two electrodes, in order to modulate neuronal activity. Twenty healthy adults were counterbalanced to receive either tDCS (experimental condition) or no tDCS (control condition) for 3 days. During administration of tDCS, participants performed a balance task significantly faster than controls. After tDCS, subjects significantly improved their simple and choice reaction time. These results demonstrate that the SMA is highly involved in planning and executing fine and gross motor skill tasks and that tDCS is an effective modality for increasing SMA-related performance on these tasks. The findings may be generalizable and therefore indicate implications for future interventions using tDCS as a therapeutic tool.

Driving performance in a power wheelchair simulator.

PubMed

Archambault, Philippe S; Tremblay, Stéphanie; Cachecho, Sarah; Routhier, François; Boissy, Patrick

2012-05-01

A power wheelchair simulator can allow users to safely experience various driving tasks. For such training to be efficient, it is important that driving performance be equivalent to that in a real wheelchair. This study aimed at comparing driving performance in a real and in a simulated environment. Two groups of healthy young adults performed different driving tasks, either in a real power wheelchair or in a simulator. Smoothness of joystick control as well as the time necessary to complete each task were recorded and compared between the two groups. Driving strategies were analysed from video recordings. The sense of presence, of really being in the virtual environment, was assessed through a questionnaire. Smoothness of joystick control was the same in the real and virtual groups. Task completion time was higher in the simulator for the more difficult tasks. Both groups showed similar strategies and difficulties. The simulator generated a good sense of presence, which is important for motivation. Performance was very similar for power wheelchair driving in the simulator or in real life. Thus, the simulator could potentially be used to complement training of individuals who require a power wheelchair and use a regular joystick. [Box: see text].

Acquisition, retention and transfer of simulated laparoscopic tasks using fNIR and a contextual interference paradigm.

PubMed

Shewokis, Patricia A; Shariff, Faiz U; Liu, Yichuan; Ayaz, Hasan; Castellanos, Andres; Lind, D Scott

2017-02-01

Using functional near infrared spectroscopy, a noninvasive, optical brain imaging tool that monitors changes in hemodynamics within the prefrontal cortex (PFC), we assessed performance and cognitive effort during the acquisition, retention and transfer of multiple simulated laparoscopic tasks by novice learners within a contextual interference paradigm. Third-year medical students (n = 10) were randomized to either a blocked or random practice schedule. Across 3 days, students performed 108 acquisition trials of 3 laparoscopic tasks on the LapSim ® simulator followed by delayed retention and transfer tests. Performance metrics (Global score, Total time) and hemodynamic responses (total hemoglobin (μm)) were assessed during skill acquisition, retention and transfer. All acquisition tasks resulted in significant practice schedule X trial block interactions for the left medial anterior PFC. During retention and transfer, random performed the skills in less time and had lower total hemoglobin change in the right dorsolateral PFC than blocked. Compared with blocked, random practice resulted in enhanced learning through better performance and less cognitive load for retention and transfer of simulated laparoscopic tasks. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of Cognitive Demand on Situational Interest and Running Task Performances

ERIC Educational Resources Information Center

Zhu, Xihe; Chen, Senlin

2017-01-01

This study examined the effect of cognitive demand on situational interest and performance using running tasks in physical education. Adolescents (N = 179) participated in a field study involving three different levels of cognitive demand. Running performances and situational interest were measured four times with a testing interval of seven days.…

The source of dual-task limitations: Serial or parallel processing of multiple response selections?

PubMed Central

Marois, René

2014-01-01

Although it is generally recognized that the concurrent performance of two tasks incurs costs, the sources of these dual-task costs remain controversial. The serial bottleneck model suggests that serial postponement of task performance in dual-task conditions results from a central stage of response selection that can only process one task at a time. Cognitive-control models, by contrast, propose that multiple response selections can proceed in parallel, but that serial processing of task performance is predominantly adopted because its processing efficiency is higher than that of parallel processing. In the present study, we empirically tested this proposition by examining whether parallel processing would occur when it was more efficient and financially rewarded. The results indicated that even when parallel processing was more efficient and was incentivized by financial reward, participants still failed to process tasks in parallel. We conclude that central information processing is limited by a serial bottleneck. PMID:23864266

Cultural differences in visual attention: Implications for distraction processing.

PubMed

Amer, Tarek; Ngo, K W Joan; Hasher, Lynn

2017-05-01

We investigated differences between participants of East Asian and Western descent in attention to and implicit memory for irrelevant words which participants were instructed to ignore while completing a target task (a Stroop Task in Experiment 1 and a 1-back task on pictures in Experiment 2). Implicit memory was measured using two conceptual priming tasks (category generation in Experiment 1 and general knowledge in Experiment 2). Participants of East Asian descent showed reliable implicit memory for previous distractors relative to those of Western descent with no evidence of differences on target task performance. We also found differences in a Corsi Block spatial memory task in both studies, with superior performance by the East Asian group. Our findings suggest that cultural differences in attention extend to task-irrelevant background information, and demonstrate for the first time that such information can boost performance when it becomes relevant on a subsequent task. © 2016 The British Psychological Society.

Lexical processing while deciding what task to perform: reading aloud in the context of the task set paradigm.

PubMed

O'Malley, Shannon; Besner, Derek

2011-12-01

The results of two experiments provide the first direct demonstration that subjects can process a word lexically despite concurrently being engaged in decoding a task cue telling them which of two tasks to perform. These results, taken together with others, point to qualitative differences between the mind's ability to engage in lexical versus sublexical processing during the time they are engaged with other tasks. The emerging picture is one in which some form of resource(s) plays little role during lexical processing whereas the need for some form of resource(s) during sublexical processing serves to bottleneck performance. Copyright © 2011 Elsevier Inc. All rights reserved.

Relating lab to life: Decrements in attention over time predict math productivity among children with ADHD.

PubMed

Fosco, Whitney D; Hawk, Larry W

2017-02-01

A child's ability to sustain attention over time (AOT) is critical in attention-deficit/hyperactivity disorder (ADHD), yet no prior work has examined the extent to which a child's decrement in AOT on laboratory tasks relates to clinically-relevant behavior. The goal of this study is to provide initial evidence for the criterion validity of laboratory assessments of AOT. A total of 20 children with ADHD (7-12 years of age) who were enrolled in a summer treatment program completed two lab attention tasks (a continuous performance task and a self-paced choice discrimination task) and math seatwork. Analyses focused on relations between attention task parameters and math productivity. Individual differences in overall attention (OA) measures (averaged across time) accounted for 23% of the variance in math productivity, supporting the criterion validity of lab measures of attention. The criterion validity was enhanced by consideration of changes in AOT. Performance on all laboratory attention measures deteriorated as time-on-task increased, and individual differences in the decrement in AOT accounted for 40% of the variance in math productivity. The only variable to uniquely predict math productivity was from the self-paced choice discrimination task. This study suggests that attention tasks in the lab do predict a clinically-relevant target behavior in children with ADHD, supporting their use as a means to study attention processes in a controlled environment. Furthermore, this prediction is improved when attention is examined as a function of time-on-task and when the attentional demands are consistent between lab and life contexts.

Workload Capacity: A Response Time-Based Measure of Automation Dependence.

PubMed

Yamani, Yusuke; McCarley, Jason S

2016-05-01

An experiment used the workload capacity measure C(t) to quantify the processing efficiency of human-automation teams and identify operators' automation usage strategies in a speeded decision task. Although response accuracy rates and related measures are often used to measure the influence of an automated decision aid on human performance, aids can also influence response speed. Mean response times (RTs), however, conflate the influence of the human operator and the automated aid on team performance and may mask changes in the operator's performance strategy under aided conditions. The present study used a measure of parallel processing efficiency, or workload capacity, derived from empirical RT distributions as a novel gauge of human-automation performance and automation dependence in a speeded task. Participants performed a speeded probabilistic decision task with and without the assistance of an automated aid. RT distributions were used to calculate two variants of a workload capacity measure, COR(t) and CAND(t). Capacity measures gave evidence that a diagnosis from the automated aid speeded human participants' responses, and that participants did not moderate their own decision times in anticipation of diagnoses from the aid. Workload capacity provides a sensitive and informative measure of human-automation performance and operators' automation dependence in speeded tasks. © 2016, Human Factors and Ergonomics Society.

PPC750 Performance Monitor

NASA Technical Reports Server (NTRS)

Meyer, Donald; Uchenik, Igor

2007-01-01

The PPC750 Performance Monitor (Perfmon) is a computer program that helps the user to assess the performance characteristics of application programs running under the Wind River VxWorks real-time operating system on a PPC750 computer. Perfmon generates a user-friendly interface and collects performance data by use of performance registers provided by the PPC750 architecture. It processes and presents run-time statistics on a per-task basis over a repeating time interval (typically, several seconds or minutes) specified by the user. When the Perfmon software module is loaded with the user s software modules, it is available for use through Perfmon commands, without any modification of the user s code and at negligible performance penalty. Per-task run-time performance data made available by Perfmon include percentage time, number of instructions executed per unit time, dispatch ratio, stack high water mark, and level-1 instruction and data cache miss rates. The performance data are written to a file specified by the user or to the serial port of the computer

Human-centric predictive model of task difficulty for human-in-the-loop control tasks

PubMed Central

Majewicz Fey, Ann

2018-01-01

Quantitatively measuring the difficulty of a manipulation task in human-in-the-loop control systems is ill-defined. Currently, systems are typically evaluated through task-specific performance measures and post-experiment user surveys; however, these methods do not capture the real-time experience of human users. In this study, we propose to analyze and predict the difficulty of a bivariate pointing task, with a haptic device interface, using human-centric measurement data in terms of cognition, physical effort, and motion kinematics. Noninvasive sensors were used to record the multimodal response of human user for 14 subjects performing the task. A data-driven approach for predicting task difficulty was implemented based on several task-independent metrics. We compare four possible models for predicting task difficulty to evaluated the roles of the various types of metrics, including: (I) a movement time model, (II) a fusion model using both physiological and kinematic metrics, (III) a model only with kinematic metrics, and (IV) a model only with physiological metrics. The results show significant correlation between task difficulty and the user sensorimotor response. The fusion model, integrating user physiology and motion kinematics, provided the best estimate of task difficulty (R2 = 0.927), followed by a model using only kinematic metrics (R2 = 0.921). Both models were better predictors of task difficulty than the movement time model (R2 = 0.847), derived from Fitt’s law, a well studied difficulty model for human psychomotor control. PMID:29621301

Reduction of nocturnal slow-wave activity affects daytime vigilance lapses and memory encoding but not reaction time or implicit learning.

PubMed

Van Der Werf, Ysbrand D; Altena, Ellemarije; Vis, José C; Koene, Teddy; Van Someren, Eus J W

2011-01-01

Total sleep deprivation in healthy subjects has a profound effect on the performance on tasks measuring sustained attention or vigilance. We here report how a selective disruption of deep sleep only, that is, selective slow-wave activity (SWA) reduction, affects the performance of healthy well-sleeping subjects on several tasks: a "simple" and a "complex" vigilance task, a declarative learning task, and an implicit learning task despite unchanged duration of sleep. We used automated electroencephalogram (EEG) dependent acoustic feedback aimed at selective interference with-and reduction of-SWA. In a within-subject repeated measures crossover design, performance on the tasks was assessed in 13 elderly adults without sleep complaints after either SWA-reduction or after normal sleep. The number of vigilance lapses increased as a result of SWA reduction, irrespective of the type of vigilance task. Recognition on the declarative memory task was also affected by SWA reduction, associated with a decreased activation of the right hippocampus on encoding (measured with fMRI) suggesting a weaker memory trace. SWA reduction, however, did not affect reaction time on either of the vigilance tasks or implicit memory task performance. These findings suggest a specific role of slow oscillations in the subsequent daytime ability to maintain sustained attention and to encode novel declarative information but not to maintain response speed or to build implicit memories. Of particular interest is that selective SWA reduction can mimic some of the effects of total sleep deprivation, while not affecting sleep duration. Copyright © 2011 Elsevier B.V. All rights reserved.

Optimal dynamic voltage scaling for wireless sensor nodes with real-time constraints

NASA Astrophysics Data System (ADS)

Cassandras, Christos G.; Zhuang, Shixin

2005-11-01

Sensors are increasingly embedded in manufacturing systems and wirelessly networked to monitor and manage operations ranging from process and inventory control to tracking equipment and even post-manufacturing product monitoring. In building such sensor networks, a critical issue is the limited and hard to replenish energy in the devices involved. Dynamic voltage scaling is a technique that controls the operating voltage of a processor to provide desired performance while conserving energy and prolonging the overall network's lifetime. We consider such power-limited devices processing time-critical tasks which are non-preemptive, aperiodic and have uncertain arrival times. We treat voltage scaling as a dynamic optimization problem whose objective is to minimize energy consumption subject to hard or soft real-time execution constraints. In the case of hard constraints, we build on prior work (which engages a voltage scaling controller at task completion times) by developing an intra-task controller that acts at all arrival times of incoming tasks. We show that this optimization problem can be decomposed into two simpler ones whose solution leads to an algorithm that does not actually require solving any nonlinear programming problems. In the case of soft constraints, this decomposition must be partly relaxed, but it still leads to a scalable (linear in the number of tasks) algorithm. Simulation results are provided to illustrate performance improvements in systems with intra-task controllers compared to uncontrolled systems or those using inter-task control.

Single pellet grasping following cervical spinal cord injury in adult rat using an automated full-time training robot

PubMed Central

Fenrich, Keith K.; May, Zacincte; Torres-Espín, Abel; Forero, Juan; Bennett, David J.; Fouad, Karim

2016-01-01

Task specific motor training is a common form of rehabilitation therapy in individuals with spinal cord injury (SCI). The single pellet grasping (SPG) task is a skilled forelimb motor task used to evaluate recovery of forelimb function in rodent models of SCI. The task requires animals to obtain food pellets located on a shelf beyond a slit at the front of an enclosure. Manually training and testing rats in the SPG task requires extensive time and often yields results with high outcome variability and small therapeutic windows (i.e., the difference between pre- and post-SCI success rates). Recent advances in automated SPG training using automated pellet presentation (APP) systems allow rats to train ad libitum 24 h a day, 7 days a week. APP trained rats have improved success rates, require less researcher time, and have lower outcome variability compared to manually trained rats. However, it is unclear whether APP trained rats can perform the SPG task using the APP system after SCI. Here we show that rats with cervical SCI can successfully perform the SPG task using the APP system. We found that SCI rats with APP training performed significantly more attempts, had slightly lower and less variable final score success rates, and larger therapeutic windows than SCI rats with manual training. These results demonstrate that APP training has clear advantages over manual training for evaluating reaching performance of SCI rats and represents a new tool for investigating rehabilitative motor training following CNS injury. PMID:26611563

Single pellet grasping following cervical spinal cord injury in adult rat using an automated full-time training robot.

PubMed

Fenrich, Keith K; May, Zacincte; Torres-Espín, Abel; Forero, Juan; Bennett, David J; Fouad, Karim

2016-02-15

Task specific motor training is a common form of rehabilitation therapy in individuals with spinal cord injury (SCI). The single pellet grasping (SPG) task is a skilled forelimb motor task used to evaluate recovery of forelimb function in rodent models of SCI. The task requires animals to obtain food pellets located on a shelf beyond a slit at the front of an enclosure. Manually training and testing rats in the SPG task requires extensive time and often yields results with high outcome variability and small therapeutic windows (i.e., the difference between pre- and post-SCI success rates). Recent advances in automated SPG training using automated pellet presentation (APP) systems allow rats to train ad libitum 24h a day, 7 days a week. APP trained rats have improved success rates, require less researcher time, and have lower outcome variability compared to manually trained rats. However, it is unclear whether APP trained rats can perform the SPG task using the APP system after SCI. Here we show that rats with cervical SCI can successfully perform the SPG task using the APP system. We found that SCI rats with APP training performed significantly more attempts, had slightly lower and less variable final score success rates, and larger therapeutic windows than SCI rats with manual training. These results demonstrate that APP training has clear advantages over manual training for evaluating reaching performance of SCI rats and represents a new tool for investigating rehabilitative motor training following CNS injury. Copyright © 2015 Elsevier B.V. All rights reserved.

CQPSO scheduling algorithm for heterogeneous multi-core DAG task model

NASA Astrophysics Data System (ADS)

Zhai, Wenzheng; Hu, Yue-Li; Ran, Feng

2017-07-01

Efficient task scheduling is critical to achieve high performance in a heterogeneous multi-core computing environment. The paper focuses on the heterogeneous multi-core directed acyclic graph (DAG) task model and proposes a novel task scheduling method based on an improved chaotic quantum-behaved particle swarm optimization (CQPSO) algorithm. A task priority scheduling list was built. A processor with minimum cumulative earliest finish time (EFT) was acted as the object of the first task assignment. The task precedence relationships were satisfied and the total execution time of all tasks was minimized. The experimental results show that the proposed algorithm has the advantage of optimization abilities, simple and feasible, fast convergence, and can be applied to the task scheduling optimization for other heterogeneous and distributed environment.

Watching the clock

PubMed Central

Fetterman, J. Gregor; Killeen, Peter R.; Hall, Scott

2008-01-01

Four rats and four pigeons were monitored while performing retrospective timing tasks. All animals displayed collateral behaviors which could have mediated their temporal judgements. Statistical analysis made a good case for such mediation in the case of two pigeons performing on a spatially-differentiated response, but not for the two responding on a color-differentiated response. For the rats, all of which performed on a spatially-differentiated task, prediction of their temporal judgements was always better if based on collateral activity than if based on the passage of time. PMID:19701487

Implicit Behavioral Change in Response to Cognitive Tasks in Alzheimer Disease.

PubMed

Bomilcar, Iris; Morris, Robin G; Brown, Richard G; Mograbi, Daniel C

2018-03-01

Lack of awareness about impairments is commonly found in Alzheimer disease (AD), but recent evidence suggests that patients may respond to the experience of illness despite limited awareness. In this study, we explored whether implicit emotional responses to experiences of failure in cognitive tasks would result in longer-term change in behavior. Twenty-two patients with AD were seen 1 week after a previous session in which they performed computer tasks that had been manipulated to be either too difficult (failure condition) or very easy (success condition) for them. At the second session, both types of tasks were set to have medium difficulty and were administered so that the participants decided how long to persist on each task. Task persistence was determined by relative time spent doing the tasks, considering that participants would be more likely to stop performing tasks in which they had experienced failure during the first session. Task persistence in the second session was not affected by performance in the first session. However, when participants' awareness of performance in the first session was taken into account, differences were found in persistence between tasks in the second session. During the second session, participants stopped performing tasks after a sequence of errors. There were no self-reported changes in motivation or enjoyment in response to task failure. These findings suggest that implicit learning of task valence may be compromised in AD, but that initial moments of awareness of performance may influence long-term adaptation in unaware patients.

Brain Network Changes and Memory Decline in Aging

PubMed Central

Beason-Held, Lori L.; Hohman, Timothy J.; Venkatraman, Vijay; An, Yang; Resnick, Susan M.

2016-01-01

One theory of age-related cognitive decline proposes that changes within the default mode network (DMN) of the brain impact the ability to successfully perform cognitive operations. To investigate this theory, we examined functional covariance within brain networks using regional cerebral blood flow data, measured by 15O-water PET, from 99 participants (mean baseline age 68.6 ±7.5) in the Baltimore Longitudinal Study of Aging collected over a 7.4 year period. The sample was divided in tertiles based on longitudinal performance on a verbal recognition memory task administered during scanning, and functional covariance was compared between the upper (improvers) and lower (decliners) tertile groups. The DMN and verbal memory networks (VMN) were then examined during the verbal memory scan condition. For each network, group differences in node-to-network coherence and individual node-to-node covariance relationships were assessed at baseline and in change over time. Compared with improvers, decliners showed differences in node-to-network coherence and in node-to-node relationships in the DMN but not the VMN during verbal memory. These DMN differences reflected greater covariance with better task performance at baseline and both increasing and declining covariance with declining task performance over time for decliners. When examined during the resting state alone, the direction of change in DMN covariance was similar to that seen during task performance, but node-to-node relationships differed from those observed during the task condition. These results suggest that disengagement of DMN components during task performance is not essential for successful cognitive performance as previously proposed. Instead, a proper balance in network processes may be needed to support optimal task performance. PMID:27319002

Improved Cognition While Cycling in Parkinson’s Disease Patients and Healthy Adults

PubMed Central

Hazamy, Audrey A.; Altmann, Lori J. P.; Stegemöller, Elizabeth; Bowers, Dawn; Lee, Hyo Keun; Wilson, Jonathan; Okun, Michael S.; Hass, Chris J.

2017-01-01

Persons with Parkinson’s disease (PD) are typically more susceptible than healthy adults to impaired performance when two tasks (dual task interference) are performed simultaneously. This limitation has by many experts been attributed to limitations in cognitive resources. Nearly all studies of dual task performance in PD employ walking or balance-based motor tasks, which are commonly impaired in PD. These tasks can be performed using a combination of one or two executive function tasks. The current study examined whether persons with PD would demonstrate greater dual task effects on cognition compared to healthy older adults (HOAs) during a concurrent cycling task. Participants with and without PD completed a battery of 12 cognitive tasks assessing visual and verbal processing in the following cognitive domains: speed of processing, controlled processing, working memory and executive function. Persons with PD exhibited impairments compared to healthy participants in select tasks (i.e., 0-Back, 2-Back and operation span). Further, both groups unexpectedly exhibited dual task facilitation of response times in visual tasks across cognitive domains, and improved verbal recall during an executive function task. Only one measure, 2-back, showed a speed-accuracy trade-off in the dual task. These results demonstrate that, when paired with a motor task in which they are not impaired, people with PD exhibit similar dual task effects on cognitive tasks as HOAs, even when these dual task effects are facilitative. More generally, these findings demonstrate that pairing cognitive tasks with cycling may actually improve cognitive performance which may have therapeutic relevance to cognitive decline associated with aging and PD pathology. PMID:28088064

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.

I. WORKING MEMORY CAPACITY IN CONTEXT: MODELING DYNAMIC PROCESSES OF BEHAVIOR, MEMORY, AND DEVELOPMENT.

PubMed

Simmering, Vanessa R

2016-09-01

Working memory is a vital cognitive skill that underlies a broad range of behaviors. Higher cognitive functions are reliably predicted by working memory measures from two domains: children's performance on complex span tasks, and infants' performance in looking paradigms. Despite the similar predictive power across these research areas, theories of working memory development have not connected these different task types and developmental periods. The current project takes a first step toward bridging this gap by presenting a process-oriented theory, focusing on two tasks designed to assess visual working memory capacity in infants (the change-preference task) versus children and adults (the change detection task). Previous studies have shown inconsistent results, with capacity estimates increasing from one to four items during infancy, but only two to three items during early childhood. A probable source of this discrepancy is the different task structures used with each age group, but prior theories were not sufficiently specific to explain how performance relates across tasks. The current theory focuses on cognitive dynamics, that is, how memory representations are formed, maintained, and used within specific task contexts over development. This theory was formalized in a computational model to generate three predictions: 1) capacity estimates in the change-preference task should continue to increase beyond infancy; 2) capacity estimates should be higher in the change-preference versus change detection task when tested within individuals; and 3) performance should correlate across tasks because both rely on the same underlying memory system. I also tested a fourth prediction, that development across tasks could be explained through increasing real-time stability, realized computationally as strengthening connectivity within the model. Results confirmed these predictions, supporting the cognitive dynamics account of performance and developmental changes in real-time stability. The monograph concludes with implications for understanding memory, behavior, and development in a broader range of cognitive development. © 2016 The Society for Research in Child Development, Inc.

Examining the stability of dual-task posture and reaction time measures in older adults over five sessions: a pilot study.

PubMed

Jehu, Deborah A; Paquet, Nicole; Lajoie, Yves

2016-12-01

Improved performance may be inherent due to repeated exposure to a testing protocol. However, limited research has examined this phenomenon in postural control. The aim was to determine the influence of repeated administration of a dual-task testing protocol once per week for 5 weeks on postural sway and reaction time. Ten healthy older adults (67.0 ± 6.9 years) stood on a force plate for 30 s in feet apart and semi-tandem positions while completing simple reaction time (SRT) and choice reaction time (CRT) tasks. They were instructed to stand as still as possible while verbally responding as fast as possible to the stimuli. No significant differences in postural sway were shown over time (p > 0.05). A plateau in average CRT emerged as the time effect revealed longer CRT during session 1 compared to sessions 3-5 (p < 0.05). Furthermore, the time effect for within-subject variability of CRT uncovered no plateaus as it was less variable in session 5 than sessions 1-4 (p < 0.05). The lack of a plateau in variability of CRT may have emerged as older adults may require longer to reach optimal performance potential in a dual-task context. Postural sway and SRT were stable over the 5 testing sessions, but variability of CRT continued to improve over time. These findings form a basis for future studies to examine performance-related improvements due to repeated exposure to a testing protocol in a dual-task setting.

Emotional reactivity and awareness of task performance in Alzheimer's disease.

PubMed

Mograbi, Daniel C; Brown, Richard G; Salas, Christian; Morris, Robin G

2012-07-01

Lack of awareness about performance in tasks is a common feature of Alzheimer's disease. Nevertheless, clinical anecdotes have suggested that patients may show emotional or behavioural responses to the experience of failure despite reporting limited awareness, an aspect which has been little explored experimentally. The current study investigated emotional reactions to success or failure in tasks despite unawareness of performance in Alzheimer's disease. For this purpose, novel computerised tasks which expose participants to systematic success or failure were used in a group of Alzheimer's disease patients (n=23) and age-matched controls (n=21). Two experiments, the first with reaction time tasks and the second with memory tasks, were carried out, and in each experiment two parallel tasks were used, one in a success condition and one in a failure condition. Awareness of performance was measured comparing participant estimations of performance with actual performance. Emotional reactivity was assessed with a self-report questionnaire and rating of filmed facial expressions. In both experiments the results indicated that, relative to controls, Alzheimer's disease patients exhibited impaired awareness of performance, but comparable differential reactivity to failure relative to success tasks, both in terms of self-report and facial expressions. This suggests that affective valence of failure experience is processed despite unawareness of task performance, which might indicate implicit processing of information in neural pathways bypassing awareness. Copyright © 2012 Elsevier Ltd. All rights reserved.

Improvements in motor tasks through the use of smartphone technology for individuals with Duchenne muscular dystrophy.

PubMed

Capelini, Camila Miliani; da Silva, Talita Dias; Tonks, James; Watson, Suzanna; Alvarez, Mayra Priscila Boscolo; de Menezes, Lilian Del Ciello; Favero, Francis Meire; Caromano, Fátima Aparecida; Massetti, Thais; de Mello Monteiro, Carlos Bandeira

2017-01-01

In individuals severely affected with Duchenne muscular dystrophy (DMD), virtual reality has recently been used as a tool to enhance community interaction. Smartphones offer the exciting potential to improve communication, access, and participation, and present the unique opportunity to directly deliver functionality to people with disabilities. To verify whether individuals with DMD improve their motor performance when undertaking a visual motor task using a smartphone game. Fifty individuals with DMD and 50 healthy, typically developing (TD) controls, aged 10-34 years participated in the study. The functional characterization of the sample was determined through Vignos, Egen Klassifikation, and the Motor Function Measure scales. To complete the task, individuals moved a virtual ball around a virtual maze and the time in seconds was measured after every attempt in order to analyze improvement of performance after the practice trials. Motor performance (time to finish each maze) was measured in phases of acquisition, short-term retention, and transfer. Use of the smartphone maze game promoted improvement in performance during acquisition in both groups, which remained in the retention phase. At the transfer phases, with alternative maze tasks, the performance in DMD group was similar to the performance of TD group, with the exception of the transfer to the contralateral hand (nondominant). However, the group with DMD demonstrated longer movement time at all stages of learning, compared with the TD group. The practice of a visual motor task delivered via smartphone game promoted an improvement in performance with similar patterns of learning in both groups. Performance can be influenced by task difficulty, and for people with DMD, motor deficits are responsible for the lower speed of execution. This study indicates that individuals with DMD showed improved performance in a short-term motor learning protocol using a smartphone. We advocate that this technology could be used to promote function in this population.

Improvements in motor tasks through the use of smartphone technology for individuals with Duchenne muscular dystrophy

PubMed Central

Capelini, Camila Miliani; da Silva, Talita Dias; Tonks, James; Watson, Suzanna; Alvarez, Mayra Priscila Boscolo; de Menezes, Lilian Del Ciello; Favero, Francis Meire; Caromano, Fátima Aparecida; Massetti, Thais; de Mello Monteiro, Carlos Bandeira

2017-01-01

Background In individuals severely affected with Duchenne muscular dystrophy (DMD), virtual reality has recently been used as a tool to enhance community interaction. Smartphones offer the exciting potential to improve communication, access, and participation, and present the unique opportunity to directly deliver functionality to people with disabilities. Objective To verify whether individuals with DMD improve their motor performance when undertaking a visual motor task using a smartphone game. Patients and methods Fifty individuals with DMD and 50 healthy, typically developing (TD) controls, aged 10–34 years participated in the study. The functional characterization of the sample was determined through Vignos, Egen Klassifikation, and the Motor Function Measure scales. To complete the task, individuals moved a virtual ball around a virtual maze and the time in seconds was measured after every attempt in order to analyze improvement of performance after the practice trials. Motor performance (time to finish each maze) was measured in phases of acquisition, short-term retention, and transfer. Results Use of the smartphone maze game promoted improvement in performance during acquisition in both groups, which remained in the retention phase. At the transfer phases, with alternative maze tasks, the performance in DMD group was similar to the performance of TD group, with the exception of the transfer to the contralateral hand (nondominant). However, the group with DMD demonstrated longer movement time at all stages of learning, compared with the TD group. Conclusion The practice of a visual motor task delivered via smartphone game promoted an improvement in performance with similar patterns of learning in both groups. Performance can be influenced by task difficulty, and for people with DMD, motor deficits are responsible for the lower speed of execution. This study indicates that individuals with DMD showed improved performance in a short-term motor learning protocol using a smartphone. We advocate that this technology could be used to promote function in this population. PMID:28860778

The JFK BIG study: the impact of LSVT BIG® on dual task walking and mobility in persons with Parkinson’s disease

PubMed Central

Isaacson, Sara; O’Brien, Ashley; Lazaro, Jennifer D.; Ray, Arlen; Fluet, Gerard

2018-01-01

[Purpose] The aim of this study was to test the hypothesis that Lee Silverman Voice Treatment-BIG decreases the negative impact of hypokinesia on dual task performance in persons with Parkinson’s disease. [Subjects and Methods] The records of 114 patients with Parkinson’s admitted to outpatient rehabilitation at a suburban hospital were reviewed. Demographics and data for 8 outcome measures were extracted for subjects that completed 14 of 16 sessions of BIG. 93 of these subjects had records of pre and post-test Timed Up and Go, Timed Up and Go Motor, and Timed Up and Go Cognitive scores. Average age was 68.4 years (SD=10.6) and average disease duration was 4.9 years (SD=5.3). [Results] Subjects demonstrated statistically significant improvements for Timed Up and Go (3.3 SD=4.5), Timed Up and Go Motor (4.4 SD=5.8) and Timed Up and Go Cognitive (4.7 SD=5.4). Concurrent motor and cognitive performance remained stable. Dual task cost decreased at a statistically significant level for Timed Up and Go Cognitive (7% SD=31%) but not Motor (4% SD=32%). [Conclusion] These findings suggest that cueing strategies associated with LSVT BIG become internalized and decrease the negative impact of hypokinesia on mobility and cognitive performance while performing two tasks simultaneously in persons with Parkinson’s. PMID:29706722

Workflow Dynamics and the Imaging Value Chain: Quantifying the Effect of Designating a Nonimage-Interpretive Task Workflow.

PubMed

Lee, Matthew H; Schemmel, Andrew J; Pooler, B Dustin; Hanley, Taylor; Kennedy, Tabassum A; Field, Aaron S; Wiegmann, Douglas; Yu, John-Paul J

To assess the impact of separate non-image interpretive task and image-interpretive task workflows in an academic neuroradiology practice. A prospective, randomized, observational investigation of a centralized academic neuroradiology reading room was performed. The primary reading room fellow was observed over a one-month period using a time-and-motion methodology, recording frequency and duration of tasks performed. Tasks were categorized into separate image interpretive and non-image interpretive workflows. Post-intervention observation of the primary fellow was repeated following the implementation of a consult assistant responsible for non-image interpretive tasks. Pre- and post-intervention data were compared. Following separation of image-interpretive and non-image interpretive workflows, time spent on image-interpretive tasks by the primary fellow increased from 53.8% to 73.2% while non-image interpretive tasks decreased from 20.4% to 4.4%. Mean time duration of image interpretation nearly doubled, from 05:44 to 11:01 (p = 0.002). Decreases in specific non-image interpretive tasks, including phone calls/paging (2.86/hr versus 0.80/hr), in-room consultations (1.36/hr versus 0.80/hr), and protocoling (0.99/hr versus 0.10/hr), were observed. The consult assistant experienced 29.4 task switching events per hour. Rates of specific non-image interpretive tasks for the CA were 6.41/hr for phone calls/paging, 3.60/hr for in-room consultations, and 3.83/hr for protocoling. Separating responsibilities into NIT and IIT workflows substantially increased image interpretation time and decreased TSEs for the primary fellow. Consolidation of NITs into a separate workflow may allow for more efficient task completion. Copyright © 2017 Elsevier Inc. All rights reserved.

Interference effects of vocalization on dual task performance

NASA Astrophysics Data System (ADS)

Owens, J. M.; Goodman, L. S.; Pianka, M. J.

1984-09-01

Voice command and control systems have been proposed as a potential means of off-loading the typically overburdened visual information processing system. However, prior to introducing novel human-machine interfacing technologies in high workload environments, consideration must be given to the integration of the new technologists within existing task structures to ensure that no new sources of workload or interference are systematically introduced. This study examined the use of voice interactive systems technology in the joint performance of two cognitive information processing tasks requiring continuous memory and choice reaction wherein a basis for intertask interference might be expected. Stimuli for the continuous memory task were presented aurally and either voice or keyboard responding was required in the choice reaction task. Performance was significantly degraded in each task when voice responding was required in the choice reaction time task. Performance degradation was evident in higher error scores for both the choice reaction and continuous memory tasks. Performance decrements observed under conditions of high intertask stimulus similarity were not statistically significant. The results signal the need to consider further the task requirements for verbal short-term memory when applying speech technology in multitask environments.

Perceptual Learning in the Absence of Task or Stimulus Specificity

PubMed Central

Webb, Ben S.; Roach, Neil W.; McGraw, Paul V.

2007-01-01

Performance on most sensory tasks improves with practice. When making particularly challenging sensory judgments, perceptual improvements in performance are tightly coupled to the trained task and stimulus configuration. The form of this specificity is believed to provide a strong indication of which neurons are solving the task or encoding the learned stimulus. Here we systematically decouple task- and stimulus-mediated components of trained improvements in perceptual performance and show that neither provides an adequate description of the learning process. Twenty-four human subjects trained on a unique combination of task (three-element alignment or bisection) and stimulus configuration (vertical or horizontal orientation). Before and after training, we measured subjects' performance on all four task-configuration combinations. What we demonstrate for the first time is that learning does actually transfer across both task and configuration provided there is a common spatial axis to the judgment. The critical factor underlying the transfer of learning effects is not the task or stimulus arrangements themselves, but rather the recruitment of commons sets of neurons most informative for making each perceptual judgment. PMID:18094748

Perceived task complexity of trunk stability exercises.

PubMed

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

2017-02-01

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

Performance on a computerized shopping task significantly predicts real world functioning in persons diagnosed with bipolar disorder.

PubMed

Laloyaux, Julien; Pellegrini, Nadia; Mourad, Haitham; Bertrand, Hervé; Domken, Marc-André; Van der Linden, Martial; Larøi, Frank

2013-12-15

Persons diagnosed with bipolar disorder often suffer from cognitive impairments. However, little is known concerning how these cognitive deficits impact their real world functioning. We developed a computerized real-life activity task, where participants are required to shop for a list of grocery store items. Twenty one individuals diagnosed with bipolar disorder and 21 matched healthy controls were administered the computerized shopping task. Moreover, the patient group was assessed with a battery of cognitive tests and clinical scales. Performance on the shopping task significantly differentiated patients and healthy controls for two variables: Total time to complete the shopping task and Mean time spent to consult the shopping list. Moreover, in the patient group, performance on these variables from the shopping task correlated significantly with cognitive functioning (i.e. processing speed, verbal episodic memory, planning, cognitive flexibility, and inhibition) and with clinical variables including duration of illness and real world functioning. Finally, variables from the shopping task were found to significantly explain 41% of real world functioning of patients diagnosed with bipolar disorder. These findings suggest that the shopping task provides a good indication of real world functioning and cognitive functioning of persons diagnosed with bipolar disorder. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Effect of type of cognitive task and walking speed on cognitive-motor interference during dual-task walking.

PubMed

Patel, P; Lamar, M; Bhatt, T

2014-02-28

We aimed to determine the effect of distinctly different cognitive tasks and walking speed on cognitive-motor interference of dual-task walking. Fifteen healthy adults performed four cognitive tasks: visuomotor reaction time (VMRT) task, word list generation (WLG) task, serial subtraction (SS) task, and the Stroop (STR) task while sitting and during walking at preferred-speed (dual-task normal walking) and slow-speed (dual-task slow-speed walking). Gait speed was recorded to determine effect on walking. Motor and cognitive costs were measured. Dual-task walking had a significant effect on motor and cognitive parameters. At preferred-speed, the motor cost was lowest for the VMRT task and highest for the STR task. In contrast, the cognitive cost was highest for the VMRT task and lowest for the STR task. Dual-task slow walking resulted in increased motor cost and decreased cognitive cost only for the STR task. Results show that the motor and cognitive cost of dual-task walking depends heavily on the type and perceived complexity of the cognitive task being performed. Cognitive cost for the STR task was low irrespective of walking speed, suggesting that at preferred-speed individuals prioritize complex cognitive tasks requiring higher attentional and processing resources over walking. While performing VMRT task, individuals preferred to prioritize more complex walking task over VMRT task resulting in lesser motor cost and increased cognitive cost for VMRT task. Furthermore, slow walking can assist in diverting greater attention towards complex cognitive tasks, improving its performance while walking. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

The influence of visual and vestibular orientation cues in a clock reading task.

PubMed

Davidenko, Nicolas; Cheong, Yeram; Waterman, Amanda; Smith, Jacob; Anderson, Barrett; Harmon, Sarah

2018-05-23

We investigated how performance in the real-life perceptual task of analog clock reading is influenced by the clock's orientation with respect to egocentric, gravitational, and visual-environmental reference frames. In Experiment 1, we designed a simple clock-reading task and found that observers' reaction time to correctly tell the time depends systematically on the clock's orientation. In Experiment 2, we dissociated egocentric from environmental reference frames by having participants sit upright or lie sideways while performing the task. We found that both reference frames substantially contribute to response times in this task. In Experiment 3, we placed upright or rotated participants in an upright or rotated immersive virtual environment, which allowed us to further dissociate vestibular from visual cues to the environmental reference frame. We found evidence of environmental reference frame effects only when visual and vestibular cues were aligned. We discuss the implications for the design of remote and head-mounted displays. Copyright © 2018 Elsevier Inc. All rights reserved.

Quantification of deviations from rationality with heavy tails in human dynamics

NASA Astrophysics Data System (ADS)

Maillart, T.; Sornette, D.; Frei, S.; Duebendorfer, T.; Saichev, A.

2011-05-01

The dynamics of technological, economic and social phenomena is controlled by how humans organize their daily tasks in response to both endogenous and exogenous stimulations. Queueing theory is believed to provide a generic answer to account for the often observed power-law distributions of waiting times before a task is fulfilled. However, the general validity of the power law and the nature of other regimes remain unsettled. Using anonymized data collected by Google at the World Wide Web level, we identify the existence of several additional regimes characterizing the time required for a population of Internet users to execute a given task after receiving a message. Depending on the under- or over-utilization of time by the population of users and the strength of their response to perturbations, the pure power law is found to be coextensive with an exponential regime (tasks are performed without too much delay) and with a crossover to an asymptotic plateau (some tasks are never performed).

Dependency of human target detection performance on clutter and quality of supporting image analysis algorithms in a video surveillance task

NASA Astrophysics Data System (ADS)

Huber, Samuel; Dunau, Patrick; Wellig, Peter; Stein, Karin

2017-10-01

Background: In target detection, the success rates depend strongly on human observer performances. Two prior studies tested the contributions of target detection algorithms and prior training sessions. The aim of this Swiss-German cooperation study was to evaluate the dependency of human observer performance on the quality of supporting image analysis algorithms. Methods: The participants were presented 15 different video sequences. Their task was to detect all targets in the shortest possible time. Each video sequence showed a heavily cluttered simulated public area from a different viewing angle. In each video sequence, the number of avatars in the area was altered to 100, 150 and 200 subjects. The number of targets appearing was kept at 10%. The number of marked targets varied from 0, 5, 10, 20 up to 40 marked subjects while keeping the positive predictive value of the detection algorithm at 20%. During the task, workload level was assessed by applying an acoustic secondary task. Detection rates and detection times for the targets were analyzed using inferential statistics. Results: The study found Target Detection Time to increase and Target Detection Rates to decrease with increasing numbers of avatars. The same is true for the Secondary Task Reaction Time while there was no effect on Secondary Task Hit Rate. Furthermore, we found a trend for a u-shaped correlation between the numbers of markings and RTST indicating increased workload. Conclusion: The trial results may indicate useful criteria for the design of training and support of observers in observational tasks.

Anticipation measures of sequence learning: manual versus oculomotor versions of the serial reaction time task.

PubMed

Vakil, Eli; Bloch, Ayala; Cohen, Haggar

2017-03-01

The serial reaction time (SRT) task has generated a very large amount of research. Nevertheless the debate continues as to the exact cognitive processes underlying implicit sequence learning. Thus, the first goal of this study is to elucidate the underlying cognitive processes enabling sequence acquisition. We therefore compared reaction time (RT) in sequence learning in a standard manual activated (MA) to that in an ocular activated (OA) version of the task, within a single experimental setting. The second goal is to use eye movement measures to compare anticipation, as an additional indication of sequence learning, between the two versions of the SRT. Performance of the group given the MA version of the task (n = 29) was compared with that of the group given the OA version (n = 30). The results showed that although overall, RT was faster for the OA group, the rate of sequence learning was similar to that of the MA group performing the standard version of the SRT. Because the stimulus-response association is automatic and exists prior to training in the OA task, the decreased reaction time in this version of the task reflects a purer measure of the sequence learning that occurs in the SRT task. The results of this study show that eye tracking anticipation can be measured directly and can serve as a direct measure of sequence learning. Finally, using the OA version of the SRT to study sequence learning presents a significant methodological contribution by making sequence learning studies possible among populations that struggle to perform manual responses.

DISPATCH: a numerical simulation framework for the exa-scale era - I. Fundamentals

NASA Astrophysics Data System (ADS)

Nordlund, Åke; Ramsey, Jon P.; Popovas, Andrius; Küffmeier, Michael

2018-06-01

We introduce a high-performance simulation framework that permits the semi-independent, task-based solution of sets of partial differential equations, typically manifesting as updates to a collection of `patches' in space-time. A hybrid MPI/OpenMP execution model is adopted, where work tasks are controlled by a rank-local `dispatcher' which selects, from a set of tasks generally much larger than the number of physical cores (or hardware threads), tasks that are ready for updating. The definition of a task can vary, for example, with some solving the equations of ideal magnetohydrodynamics (MHD), others non-ideal MHD, radiative transfer, or particle motion, and yet others applying particle-in-cell (PIC) methods. Tasks do not have to be grid based, while tasks that are, may use either Cartesian or orthogonal curvilinear meshes. Patches may be stationary or moving. Mesh refinement can be static or dynamic. A feature of decisive importance for the overall performance of the framework is that time-steps are determined and applied locally; this allows potentially large reductions in the total number of updates required in cases when the signal speed varies greatly across the computational domain, and therefore a corresponding reduction in computing time. Another feature is a load balancing algorithm that operates `locally' and aims to simultaneously minimize load and communication imbalance. The framework generally relies on already existing solvers, whose performance is augmented when run under the framework, due to more efficient cache usage, vectorization, local time-stepping, plus near-linear and, in principle, unlimited OpenMP and MPI scaling.

Eye movements and postural control in dyslexic children performing different visual tasks.

PubMed

Razuk, Milena; Barela, José Angelo; Peyre, Hugo; Gerard, Christophe Loic; Bucci, Maria Pia

2018-01-01

The aim of this study was to examine eye movements and postural control performance among dyslexic children while reading a text and performing the Landolt reading task. Fifteen dyslexic and 15 non-dyslexic children were asked to stand upright while performing two experimental visual tasks: text reading and Landolt reading. In the text reading task, children were asked to silently read a text displayed on a monitor, while in the Landolt reading task, the letters in the text were replaced by closed circles and Landolt rings, and children were asked to scan each circle/ring in a reading-like fashion, from left to right, and to count the number of Landolt rings. Eye movements (Mobile T2®, SuriCog) and center of pressure excursions (Framiral®, Grasse, France) were recorded. Visual performance variables were total reading time, mean duration of fixation, number of pro- and retro-saccades, and amplitude of pro-saccades. Postural performance variable was the center of pressure area. The results showed that dyslexic children spent more time reading the text and had a longer duration of fixation than non-dyslexic children. However, no difference was observed between dyslexic and non-dyslexic children in the Landolt reading task. Dyslexic children performed a higher number of pro- and retro-saccades than non-dyslexic children in both text reading and Landolt reading tasks. Dyslexic children had smaller pro-saccade amplitude than non-dyslexic children in the text reading task. Finally, postural performance was poorer in dyslexic children than in non-dyslexic children. Reading difficulties in dyslexic children are related to eye movement strategies required to scan and obtain lexical and semantic meaning. However, postural control performance, which was poor in dyslexic children, is not related to lexical and semantic reading requirements and might not also be related to different eye movement behavior.

Aniracetam restores motivation reduced by satiation in a choice reaction task in aged rats.

PubMed

Nakamura, K; Kurasawa, M

2001-01-01

This study aims to examine the effects of aniracetam on satiation-induced poor performance in a choice reaction task. Aged rats that mastered the task under food restriction stably maintained the task performance for a long period. Satiation by successive free feeding greatly diminished the performance. Satiation resulted in a decreased % correct, increased % omission and prolonged choice reaction time, indicating a reduction in lever response with low choice accuracy and slow responding speed. Repeated administration of aniracetam (30 mg/kg, po, for 14 days) partially recovered the choice accuracy and lever response, but not the responding speed, task-associated motor activity or impulsivity. In addition, aniracetam did not affect the animals' weights. These results indicate that satiation reduces motivation to perform and attain the task. Aniracetam may restore motivation, probably by improving poor behavioral states (daily attentional and vigilance failures), thereby creating the driving force.

Computer task performance by subjects with Duchenne muscular dystrophy.

PubMed

Malheiros, Silvia Regina Pinheiro; da Silva, Talita Dias; Favero, Francis Meire; de Abreu, Luiz Carlos; Fregni, Felipe; Ribeiro, Denise Cardoso; de Mello Monteiro, Carlos Bandeira

2016-01-01

Two specific objectives were established to quantify computer task performance among people with Duchenne muscular dystrophy (DMD). First, we compared simple computational task performance between subjects with DMD and age-matched typically developing (TD) subjects. Second, we examined correlations between the ability of subjects with DMD to learn the computational task and their motor functionality, age, and initial task performance. The study included 84 individuals (42 with DMD, mean age of 18±5.5 years, and 42 age-matched controls). They executed a computer maze task; all participants performed the acquisition (20 attempts) and retention (five attempts) phases, repeating the same maze. A different maze was used to verify transfer performance (five attempts). The Motor Function Measure Scale was applied, and the results were compared with maze task performance. In the acquisition phase, a significant decrease was found in movement time (MT) between the first and last acquisition block, but only for the DMD group. For the DMD group, MT during transfer was shorter than during the first acquisition block, indicating improvement from the first acquisition block to transfer. In addition, the TD group showed shorter MT than the DMD group across the study. DMD participants improved their performance after practicing a computational task; however, the difference in MT was present in all attempts among DMD and control subjects. Computational task improvement was positively influenced by the initial performance of individuals with DMD. In turn, the initial performance was influenced by their distal functionality but not their age or overall functionality.

Media multitasking and behavioral measures of sustained attention.

PubMed

Ralph, Brandon C W; Thomson, David R; Seli, Paul; Carriere, Jonathan S A; Smilek, Daniel

2015-02-01

In a series of four studies, self-reported media multitasking (using the media multitasking index; MMI) and general sustained-attention ability, through performance on three sustained-attention tasks: the metronome response task (MRT), the sustained-attention-to-response task (SART), and a vigilance task (here, a modified version of the SART). In Study 1, we found that higher reports of media multitasking were associated with increased response variability (i.e., poor performance) on the MRT. However, in Study 2, no association between reported media multitasking and performance on the SART was observed. These findings were replicated in Studies 3a and 3b, in which we again assessed the relation between media multitasking and performance on both the MRT and SART in two large online samples. Finally, in Study 4, using a large online sample, we tested whether media multitasking was associated with performance on a vigilance task. Although standard vigilance decrements were observed in both sensitivity (A') and response times, media multitasking was not associated with the size of these decrements, nor was media multitasking associated with overall performance, in terms of either sensitivity or response times. Taken together, the results of the studies reported here failed to demonstrate a relation between habitual engagement in media multitasking in everyday life and a general deficit in sustained-attention processes.

More to ADHD than meets the eye: observable abnormalities in search behaviour do not account for performance deficits on a discrimination task.

PubMed

Sonuga-Barke, Edmund J S; Elgie, Sarah; Hall, Martin

2005-07-20

Children with Attention Deficit/Hyperactivity Disorder (ADHD) often perform poorly on tasks requiring sustained and systematic attention to stimuli for extended periods of time. The current paper tested the hypothesis that such deficits are the result of observable abnormalities in search behaviour (e.g., attention-onset, -duration and -sequencing), and therefore can be explained without reference to deficits in non-observable (i.e., cognitive) processes. Forty boys (20 ADHD and 20 controls) performed a computer-based complex discrimination task adapted from the Matching Familiar Figures Task with four different fixed search interval lengths (5-, 10-, 15- and 20-s). Children with ADHD identified fewer targets than controls (p < 0.001), initiated searches later, spent less time attending to stimuli, and searched in a less intensive and less systematic way (p's < 0.05). There were significant univariate associations between ADHD, task performance and search behaviour. However, there was no support for the hypothesis that abnormalities in search carried the effect of ADHD on performance. The pattern of results in fact suggested that abnormal attending during testing is a statistical marker, rather than a mediator, of ADHD performance deficits. The results confirm the importance of examining covert processes, as well as behavioural abnormalities when trying to understand the psychopathophyiology of ADHD.

Grip force control in individuals with multiple sclerosis.

PubMed

Iyengar, Veena; Santos, Marcio J; Ko, Michael; Aruin, Alexander S

2009-10-01

Appropriate regulation of grip force is essential in performance of various activities of daily living such as drinking, eating, buttoning a shirt, and so on. The extent to which individuals with multiple sclerosis (MS) are able to regulate grip forces while performing elements of the activities of daily living is largely unknown. . To investigate how individuals with MS control grip force during performance of functional tasks. . This study evaluated the grip force control in selected individuals with MS (n = 9) and healthy control subjects (n = 9) while they performed the task of lifting and placing an instrumented object on a shelf and the task of lifting the object and bringing it close to the mouth to mimic drinking. The grip forces, object acceleration, force ratio, and time lag were recorded and analyzed. . The individuals with MS used significantly larger peak grip force and force ratio than control subjects while performing both tasks and for both hands. In addition, the time lag between the peaks of grip and load forces was significantly longer in individuals with MS. . The application of excessive grip force could predispose individuals with MS to additional fatigue and musculoskeletal overuse trauma. Rehabilitation protocols for the MS population may need to account for increased levels of grip force applied during the performance of functional tasks.

SU43. The Effect of Implementation Intention on Different Types of Prospective Memory Performance in Patients With Schizophrenia

PubMed Central

Wang, Ya; Liu, Lu-lu; Gan, Ming-yuan; Tan, Shu-ping; Shum, David; Chan, Raymond

2017-01-01

Abstract Background: Prospective memory (PM) refers to remembering to execute a planned intention in the future, which can been divided as event-based PM (focal, nonfocal) and time-based PM according to the nature of the cue. Focal event-based PM, where the ongoing task requires processing of the characteristics of PM cues, has been found to be benefited from implementation intention (II, ie, an encoding strategy in the format of “if I see X, then I will do Y”). However, to date, it is unclear whether implementation intention can produce a positive effect on nonfocal event-based PM (where the ongoing task is irrelevant with the PM cues) and time-based PM. Moreover, patients with schizophrenia (SCZ) were found to have impairments in these types of PM, and few studies have been conducted to examine the effect of II on these types of PM. This study investigated whether (and how) implementation intention can improve nonfocal event-based PM and time-based PM performance in patients with SCZ. Methods: Forty-two patients with SCZ and 42 healthy control participants were administered both computerized nonfocal event-based PM task and time-based PM task. Patients and healthy controls were further randomly allocated to implementation intention condition (N = 21) and typical instruction condition (N = 21). Results: Patients with SCZ in the implementation intention group showed higher PM accuracy than the typical instruction group in both nonfocal event-based PM task (0.51 ± 0.32 vs 0.19 ± 0.29, t(40) = 3.39, P = .002) and time-based PM task (0.72 ± 0.31 vs 0.39 ± 0.40, t(40) = 2.98, P = .005). Similarly, healthy controls in the II group also showed better PM performance than the typical instruction group in both tasks (all P’s < 0.05). Time check frequency of time-based PM task in the II group of all the participants was significantly higher than the typical instruction group. Conclusion: Implementation intention is an effective strategy for improving different types of PM performance in patients with schizophrenia and can be applied for clinical settings.

Efficient mental workload estimation using task-independent EEG features.

PubMed

Roy, R N; Charbonnier, S; Campagne, A; Bonnet, S

2016-04-01

Mental workload is frequently estimated by EEG-based mental state monitoring systems. Usually, these systems use spectral markers and event-related potentials (ERPs). To our knowledge, no study has directly compared their performance for mental workload assessment, nor evaluated the stability in time of these markers and of the performance of the associated mental workload estimators.  This study proposes a comparison of two processing chains, one based on the power in five frequency bands, and one based on ERPs, both including a spatial filtering step (respectively CSP and CCA), an FLDA classification and a 10-fold cross-validation. To get closer to a real life implementation, spectral markers were extracted from a short window (i.e. towards reactive systems) that did not include any motor activity and the analyzed ERPs were elicited by a task-independent probe that required a reflex-like answer (i.e. close to the ones required by dead man's vigilance devices). The data were acquired from 20 participants who performed a Sternberg memory task for 90 min (i.e. 2/6 digits to memorize) inside which a simple detection task was inserted. The results were compared both when the testing was performed at the beginning and end of the session. Both chains performed significantly better than random; however the one based on the spectral markers had a low performance (60%) and was not stable in time. Conversely, the ERP-based chain gave very high results (91%) and was stable in time. This study demonstrates that an efficient and stable in time workload estimation can be achieved using task-independent spatially filtered ERPs elicited in a minimally intrusive manner.

Efficient mental workload estimation using task-independent EEG features

NASA Astrophysics Data System (ADS)

Roy, R. N.; Charbonnier, S.; Campagne, A.; Bonnet, S.

2016-04-01

Objective. Mental workload is frequently estimated by EEG-based mental state monitoring systems. Usually, these systems use spectral markers and event-related potentials (ERPs). To our knowledge, no study has directly compared their performance for mental workload assessment, nor evaluated the stability in time of these markers and of the performance of the associated mental workload estimators. This study proposes a comparison of two processing chains, one based on the power in five frequency bands, and one based on ERPs, both including a spatial filtering step (respectively CSP and CCA), an FLDA classification and a 10-fold cross-validation. Approach. To get closer to a real life implementation, spectral markers were extracted from a short window (i.e. towards reactive systems) that did not include any motor activity and the analyzed ERPs were elicited by a task-independent probe that required a reflex-like answer (i.e. close to the ones required by dead man’s vigilance devices). The data were acquired from 20 participants who performed a Sternberg memory task for 90 min (i.e. 2/6 digits to memorize) inside which a simple detection task was inserted. The results were compared both when the testing was performed at the beginning and end of the session. Main results. Both chains performed significantly better than random; however the one based on the spectral markers had a low performance (60%) and was not stable in time. Conversely, the ERP-based chain gave very high results (91%) and was stable in time. Significance. This study demonstrates that an efficient and stable in time workload estimation can be achieved using task-independent spatially filtered ERPs elicited in a minimally intrusive manner.

Dual-Task Performance: Influence of Frailty, Level of Physical Activity, and Cognition.

PubMed

Giusti Rossi, Paulo; Pires de Andrade, Larissa; Hotta Ansai, Juliana; Silva Farche, Ana Claudia; Carnaz, Leticia; Dalpubel, Daniela; Ferriolli, Eduardo; Assis Carvalho Vale, Francisco; de Medeiros Takahashi, Anielle Cristhine

2018-03-08

Cognition and level of physical activity have been associated with frailty syndrome. The development of tools that assess deficits related to physical and cognitive frailties simultaneously are of common interest. However, little is known about how much these aspects influence the performance of dual-task tests. Our aims were (a) to verify the influence of frailty syndrome and objectively measured physical activity and cognition on the Timed Up and Go (TUG) test and Timed Up and Go associated with dual-task (TUG-DT) performances; and (b) to compare TUG and TUG-DT performances between older adults who develop frailty syndrome. Sixty-four community-dwelling older adults were divided into frail, prefrail, and nonfrail groups, according to frailty phenotype. Assessments included anamnesis, screening of frailty syndrome, cognitive assessment (Addenbrooke's cognitive examination), placement of a triaxial accelerometer to assess level of physical activity, and TUG and TUG-DT (TUG associated with a motor-cognitive task of calling a phone number) performances. After 7 days, the accelerometer was removed. A multiple linear regression was applied to identify which independent variables could explain performances in the TUG and TUG-DT. Subsequently, the analysis of covariance test, adjusted for age, cognition, and level of physical activity covariates, was used to compare test performances. There were no differences in cognition between groups. Significant differences in the level of physical activity were found in the frail group. Compared with the frail group, the nonfrail group required less time and fewer steps to complete the TUG. Regarding the TUG-DT, cognition and age influenced the time spent and number of steps, respectively; however, no differences were found between groups. Frail older adults presented worse performance in the TUG when compared with nonfrail older adults. The dual-task test does not differentiate older adults with frailty syndrome, regardless of cognitive performance.

Are factors related to dual-task performance in people with Parkinson's disease dependent on the type of dual task?

PubMed

Strouwen, Carolien; Molenaar, Esther A L M; Keus, Samyra H J; Münks, Liesbeth; Heremans, Elke; Vandenberghe, Wim; Bloem, Bastiaan R; Nieuwboer, Alice

2016-02-01

Impaired dual-task performance significantly impacts upon functional mobility in people with Parkinson's disease (PD). The aim of this study was to identify determinants of dual-task performance in people with PD in three different dual tasks to assess their possible task-dependency. We recruited 121 home-dwelling patients with PD (mean age 65.93 years; mean disease duration 8.67 years) whom we subjected to regular walking (control condition) and to three dual-task conditions: walking combined with a backwards Digit Span task, an auditory Stroop task and a Mobile Phone task. We measured dual-task gait velocity using the GAITRite mat and dual-task reaction times and errors on the concurrent tasks as outcomes. Motor, cognitive and descriptive variables which correlated to dual-task performance (p < 0.20) were entered into a stepwise forward multiple linear regression model. Single-task gait velocity and executive function, tested by the alternating intake test, was significantly associated with gait velocity during the Digit Span (R(2) = 0.65; p < 0.001), the Stroop (R(2) = 0.73; p < 0.001) and the Mobile Phone task (R(2) = 0.62; p < 0.001). In addition, disease severity proved correlated to gait velocity during the Stroop task. Age was a surplus determinant of gait velocity while using a mobile phone. Single-task gait velocity and executive function as measured by a verbal fluency switching task were independent determinants of dual-task gait performance in people with PD. In contrast to expectation, these factors were the same across different tasks, supporting the robustness of the findings. Future study needs to determine whether these factors predict dual-task abnormalities prospectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enhanced visual processing contributes to matrix reasoning in autism

PubMed Central

Soulières, Isabelle; Dawson, Michelle; Samson, Fabienne; Barbeau, Elise B.; Sahyoun, Cherif; Strangman, Gary E.; Zeffiro, Thomas A.; Mottron, Laurent

2009-01-01

Recent behavioral investigations have revealed that autistics perform more proficiently on Raven's Standard Progressive Matrices (RSPM) than would be predicted by their Wechsler intelligence scores. A widely-used test of fluid reasoning and intelligence, the RSPM assays abilities to flexibly infer rules, manage goal hierarchies, and perform high-level abstractions. The neural substrates for these abilities are known to encompass a large frontoparietal network, with different processing models placing variable emphasis on the specific roles of the prefrontal or posterior regions. We used functional magnetic resonance imaging to explore the neural bases of autistics' RSPM problem solving. Fifteen autistic and eighteen non-autistic participants, matched on age, sex, manual preference and Wechsler IQ, completed 60 self-paced randomly-ordered RSPM items along with a visually similar 60-item pattern matching comparison task. Accuracy and response times did not differ between groups in the pattern matching task. In the RSPM task, autistics performed with similar accuracy, but with shorter response times, compared to their non-autistic controls. In both the entire sample and a subsample of participants additionally matched on RSPM performance to control for potential response time confounds, neural activity was similar in both groups for the pattern matching task. However, for the RSPM task, autistics displayed relatively increased task-related activity in extrastriate areas (BA18), and decreased activity in the lateral prefrontal cortex (BA9) and the medial posterior parietal cortex (BA7). Visual processing mechanisms may therefore play a more prominent role in reasoning in autistics. PMID:19530215

Design and testing of a functional arm orthosis in patients with neuromuscular diseases.

PubMed

Rahman, Tariq; Sample, Whitney; Seliktar, Rahamim; Scavina, Mena T; Clark, Alisa L; Moran, Kacy; Alexander, Michael A

2007-06-01

The objective of this study was to determine the utility of a passive gravity-balanced arm orthosis, the Wilmington robotic exoskeleton (WREX), for patients with neuromuscular diseases. The WREX, a four-degrees-of-freedom functional orthosis, is energized by rubber bands to eliminate gravity and is attached to the wheelchair. The development and clinical testing of WREX is described in this report. Seventeen patients (14 boys and 3 girls) with muscular disabilities participated in the study. Ages ranged from 4 to 20 years. Criteria for inclusion included a weakened arm, use of a wheelchair, the ability to grasp and release objects, and the ability to provide feedback on device use. Testing consisted of administering the Jebsen test of hand function without WREX and then testing again after approximately two weeks of wearing the WREX orthosis. The timed results of each task within the test then were compared. Specific tasks related to vertical movement required less time to perform with the WREX. A large number of subjects were able to perform the Jebsen tasks with the WREX, where they were unable to perform the task without the WREX. Patients can benefit from WREX because it increases their performance in daily living activities and makes many tasks possible. The range-of-motion in the patients' arms increased considerably, while the time required to complete some of the Jebsen test tasks decreased. Most patients were very receptive to WREX, although a few were ambivalent.

Weber (slope) analyses of timing variability in tapping and drawing tasks.

PubMed

Spencer, Rebecca M C; Zelaznik, Howard N

2003-12-01

Timing variability in continuous drawing tasks has not been found to be correlated with timing variability in repetitive finger tapping in recent studies (S. D. Robertson et al., 1999; H. N. Zelaznik, R. M. C. Spencer, & R. B. Ivry, 2002). Furthermore, the central component of timing variability, as measured by the slope of the timing variance versus the square of the timed interval, differed for tapping and drawing tasks. On the basis of those results, the authors posited that timing in tapping is explicit and as such uses a central representation of the interval to be timed, whereas timing in drawing tasks is implicit, that is, the temporal component is an emergent property of the trajectory produced. The authors examined that hypothesis in the present study by determining the linear relationship between timing variance and squared duration for tapping, circle-drawing, and line-drawing tasks. Participants (N = 50) performed 1 of 5 tasks: finger tapping, line drawing in the x dimension, line drawing in the y dimension, continuous circle drawing timed in the x dimension, or continuous circle drawing timed in the y dimension. The slopes differed significantly between finger tapping, line drawing, and circle drawing, suggesting separable sources of timing variability. The slopes of the 2 circle-drawing tasks did not differ from one another, nor did the slopes of the 2 line-drawing tasks differ significantly, suggesting a shared timing process within those tasks. Those results are evidence of a high degree of specificity in timing processes.

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

PubMed

Botzer, Assaf; Meyer, Joachim; Parmet, Yisrael

2016-09-01

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

Blinks, saccades, and fixation pauses during vigilance task performance. I., Time on task.

DOT National Transportation Integrated Search

1994-12-01

In the future, operators of complex equipment will spend more time monitoring computer controlled devices rather than having hands on control of such equipment. The operator intervenes in system operation under "unusual" conditions or when there is a...

Sequence learning in Parkinson's disease: Focusing on action dynamics and the role of dopaminergic medication.

PubMed

Ruitenberg, Marit F L; Duthoo, Wout; Santens, Patrick; Seidler, Rachael D; Notebaert, Wim; Abrahamse, Elger L

2016-12-01

Previous studies on movement sequence learning in Parkinson's disease (PD) have produced mixed results. A possible explanation for the inconsistent findings is that some studies have taken dopaminergic medication into account while others have not. Additionally, in previous studies the response modalities did not allow for an investigation of the action dynamics of sequential movements as they unfold over time. In the current study we investigated sequence learning in PD by specifically considering the role of medication status in a sequence learning task where mouse movements were performed. The focus on mouse movements allowed us to examine the action dynamics of sequential movement in terms of initiation time, movement time, movement accuracy, and velocity. PD patients performed the sequence learning task once on their regular medication, and once after overnight withdrawal from their medication. Results showed that sequence learning as reflected in initiation times was impaired when PD patients performed the task ON medication compared to OFF medication. In contrast, sequence learning as reflected in the accuracy of movement trajectories was enhanced when performing the task ON compared to OFF medication. Our findings suggest that while medication enhances execution processes of movement sequence learning, it may at the same time impair planning processes that precede actual execution. Overall, the current study extends earlier findings on movement sequence learning in PD by differentiating between various components of performance, and further refines previous dopamine overdose effects in sequence learning. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Impact of Financial Reward Contingencies on Cognitive Function Profiles in Adult ADHD

PubMed Central

Marx, Ivo; Höpcke, Cornelia; Berger, Christoph; Wandschneider, Roland; Herpertz, Sabine C.

2013-01-01

Objectives Although it is well established that cognitive performance in children with attention-deficit/hyperactivity disorder (ADHD) is affected by reward and that key deficits associated with the disorder may thereby be attenuated or even compensated, this phenomenon in adults with ADHD has thus far not been addressed. Therefore, the aim of the present study was to examine the motivating effect of financial reward on task performance in adults with ADHD by focusing on the domains of executive functioning, attention, time perception, and delay aversion. Methods We examined male and female adults aged 18–40 years with ADHD (n = 38) along with a matched control group (n = 40) using six well-established experimental paradigms. Results Impaired performance in the ADHD group was observed for stop-signal omission errors, n-back accuracy, reaction time variability in the continuous performance task, and time reproduction accuracy, and reward normalized time reproduction accuracy. Furthermore, when rewarded, subjects with ADHD exhibited longer reaction times and fewer false positives in the continuous performance task, which suggests the use of strategies to prevent impulsivity errors. Conclusions Taken together, our results support the existence of both cognitive and motivational mechanisms for the disorder, which is in line with current models of ADHD. Furthermore, our data suggest cognitive strategies of “stopping and thinking” as a possible underlying mechanism for task improvement that seems to be mediated by reward, which highlights the importance of the interaction between motivation and cognition in adult ADHD. PMID:23840573

Brief periods of NREM sleep do not promote early offline gains but subsequent on-task performance in motor skill learning.

PubMed

Maier, Jonathan G; Piosczyk, Hannah; Holz, Johannes; Landmann, Nina; Deschler, Christoph; Frase, Lukas; Kuhn, Marion; Klöppel, Stefan; Spiegelhalder, Kai; Sterr, Annette; Riemann, Dieter; Feige, Bernd; Voderholzer, Ulrich; Nissen, Christoph

2017-11-01

Sleep modulates motor learning, but its detailed impact on performance curves remains to be fully characterized. This study aimed to further determine the impact of brief daytime periods of NREM sleep on 'offline' (task discontinuation after initial training) and 'on-task' (performance within the test session) changes in motor skill performance (finger tapping task). In a mixed design (combined parallel group and repeated measures) sleep laboratory study (n=17 'active' wake vs. sleep, n=19 'passive' wake vs. sleep), performance curves were assessed prior to and after a 90min period containing either sleep, active or passive wakefulness. We observed a highly significant, but state- (that is, sleep/wake)-independent early offline gain and improved on-task performance after sleep in comparison to wakefulness. Exploratory curve fitting suggested that the observed sleep effect most likely emerged from an interaction of training-induced improvement and detrimental 'time-on-task' processes, such as fatigue. Our results indicate that brief periods of NREM sleep do not promote early offline gains but subsequent on-task performance in motor skill learning. Copyright © 2017 Elsevier Inc. All rights reserved.

Cognitive-Motor Interference on Upper Extremity Motor Performance in a Robot-Assisted Planar Reaching Task Among Patients With Stroke.

PubMed

Shin, Joon-Ho; Park, Gyulee; Cho, Duk Youn

2017-04-01

To explore motor performance on 2 different cognitive tasks during robotic rehabilitation in which motor performance was longitudinally assessed. Prospective study. Rehabilitation hospital. Patients (N=22) with chronic stroke and upper extremity impairment. A total of 640 repetitions of robot-assisted planar reaching, 5 times a week for 4 weeks. Longitudinal robotic evaluations regarding motor performance included smoothness, mean velocity, path error, and reach error by the type of cognitive task. Dual-task effects (DTEs) of motor performance were computed to analyze the effect of the cognitive task on dual-task interference. Cognitive task type influenced smoothness (P=.006), the DTEs of smoothness (P=.002), and the DTEs of reach error (P=.052). Robotic rehabilitation improved smoothness (P=.007) and reach error (P=.078), while stroke severity affected smoothness (P=.01), reach error (P<.001), and path error (P=.01). Robotic rehabilitation or severity did not affect the DTEs of motor performance. The results provide evidence for the effect of cognitive-motor interference on upper extremity performance among participants with stroke using a robotic-guided rehabilitation system. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

The Influence of Instructional Climates on Time Spent in Management Tasks and Physical Activity of 2nd-Grade Students during Physical Education

ERIC Educational Resources Information Center

Logan, Samuel W.; Robinson, Leah E.; Webster, E. Kipling; Rudisill, Mary E.

2015-01-01

The purpose of this study is to determine the effect of two physical education (PE) instructional climates (mastery, performance) on the percentage of time students spent in a) moderate-to-vigorous physical activity (MVPA) and b) management tasks during PE in 2nd-grade students. Forty-eight 2nd graders (mastery, n = 23; performance, n = 25)…

On scheduling task systems with variable service times

NASA Astrophysics Data System (ADS)

Maset, Richard G.; Banawan, Sayed A.

1993-08-01

Several strategies have been proposed for developing optimal and near-optimal schedules for task systems (jobs consisting of multiple tasks that can be executed in parallel). Most such strategies, however, implicitly assume deterministic task service times. We show that these strategies are much less effective when service times are highly variable. We then evaluate two strategies—one adaptive, one static—that have been proposed for retaining high performance despite such variability. Both strategies are extensions of critical path scheduling, which has been found to be efficient at producing near-optimal schedules. We found the adaptive approach to be quite effective.

Task-set inertia and memory-consolidation bottleneck in dual tasks.

PubMed

Koch, Iring; Rumiati, Raffaella I

2006-11-01

Three dual-task experiments examined the influence of processing a briefly presented visual object for deferred verbal report on performance in an unrelated auditory-manual reaction time (RT) task. RT was increased at short stimulus-onset asynchronies (SOAs) relative to long SOAs, showing that memory consolidation processes can produce a functional processing bottleneck in dual-task performance. In addition, the experiments manipulated the spatial compatibility of the orientation of the visual object and the side of the speeded manual response. This cross-task compatibility produced relative RT benefits only when the instruction for the visual task emphasized overlap at the level of response codes across the task sets (Experiment 1). However, once the effective task set was in place, it continued to produce cross-task compatibility effects even in single-task situations ("ignore" trials in Experiment 2) and when instructions for the visual task did not explicitly require spatial coding of object orientation (Experiment 3). Taken together, the data suggest a considerable degree of task-set inertia in dual-task performance, which is also reinforced by finding costs of switching task sequences (e.g., AC --> BC vs. BC --> BC) in Experiment 3.

The Effect of Pre-Task Planning Time on L2 Learners' Narrative Writing Performance

ERIC Educational Resources Information Center

Seyyedi, Keivan; Ismail, Shaik Abdul Malik Mohamed; Orang, Maryam; Nejad, Maryam Sharafi

2013-01-01

Building on Baddeley's cognitive psychology (2007) and Skehan's Limited Attentional Capacity Model (2009), this article reports a study of the effects of pre-task planning time (strategic planning time) on Malaysian English learners' written narratives elicited by means of a picture composition. 50 first-year undergraduate students studying at…

A new contribution to the classification of stressors affecting nursing professionals

PubMed Central

Puerto, Jesús Cremades; Soler, Loreto Maciá; Montesinos, Maria José López; Marcos, Azucena Pedraz; Chorda, Víctor Manuel González

2017-01-01

Objective: to identify and classify the most important occupational stressors affecting nursing professionals in the medical units within a hospital. Method: quantitative-qualitative, descriptive and prospective study performed with Delphi technique in the medical units of a general university hospital, with a sample of 30 nursing professionals. Results: the stressors were work overload, frequent interruptions in the accomplishment of their tasks, night working, simultaneity of performing different tasks, not having enough time to give emotional support to the patient or lack of time for some patients who need it, among others. Conclusion: the most consensual stressors were ranked as work overload, frequent interruptions in the accomplishment of their tasks, night working and, finally, simultaneity of performing different tasks. These results can be used as a tool in the clinical management of hospital units, aiming to improve the quality of life of nursing professionals, organizational models and, in addition, continuous improvement in clinical treatment. PMID:28562702

Executive Functions and Prefrontal Cortex: A Matter of Persistence?

PubMed Central

Ball, Gareth; Stokes, Paul R.; Rhodes, Rebecca A.; Bose, Subrata K.; Rezek, Iead; Wink, Alle-Meije; Lord, Louis-David; Mehta, Mitul A.; Grasby, Paul M.; Turkheimer, Federico E.

2011-01-01

Executive function is thought to originates from the dynamics of frontal cortical networks. We examined the dynamic properties of the blood oxygen level dependent time-series measured with functional MRI (fMRI) within the prefrontal cortex (PFC) to test the hypothesis that temporally persistent neural activity underlies performance in three tasks of executive function. A numerical estimate of signal persistence, the Hurst exponent, postulated to represent the coherent firing of cortical networks, was determined and correlated with task performance. Increasing persistence in the lateral PFC was shown to correlate with improved performance during an n-back task. Conversely, we observed a correlation between persistence and increasing commission error – indicating a failure to inhibit a prepotent response – during a Go/No-Go task. We propose that persistence within the PFC reflects dynamic network formation and these findings underline the importance of frequency analysis of fMRI time-series in the study of executive functions. PMID:21286223

A Modified Distributed Bees Algorithm for Multi-Sensor Task Allocation †

PubMed Central

Nof, Shimon Y.; Edan, Yael

2018-01-01

Multi-sensor systems can play an important role in monitoring tasks and detecting targets. However, real-time allocation of heterogeneous sensors to dynamic targets/tasks that are unknown a priori in their locations and priorities is a challenge. This paper presents a Modified Distributed Bees Algorithm (MDBA) that is developed to allocate stationary heterogeneous sensors to upcoming unknown tasks using a decentralized, swarm intelligence approach to minimize the task detection times. Sensors are allocated to tasks based on sensors’ performance, tasks’ priorities, and the distances of the sensors from the locations where the tasks are being executed. The algorithm was compared to a Distributed Bees Algorithm (DBA), a Bees System, and two common multi-sensor algorithms, market-based and greedy-based algorithms, which were fitted for the specific task. Simulation analyses revealed that MDBA achieved statistically significant improved performance by 7% with respect to DBA as the second-best algorithm, and by 19% with respect to Greedy algorithm, which was the worst, thus indicating its fitness to provide solutions for heterogeneous multi-sensor systems. PMID:29498683

Effort in Multitasking: Local and Global Assessment of Effort.

PubMed

Kiesel, Andrea; Dignath, David

2017-01-01

When performing multiple tasks in succession, self-organization of task order might be superior compared to external-controlled task schedules, because self-organization allows optimizing processing modes and thus reduces switch costs, and it increases commitment to task goals. However, self-organization is an additional executive control process that is not required if task order is externally specified and as such it is considered as time-consuming and effortful. To compare self-organized and externally controlled task scheduling, we suggest assessing global subjective and objectives measures of effort in addition to local performance measures. In our new experimental approach, we combined characteristics of dual tasking settings and task switching settings and compared local and global measures of effort in a condition with free choice of task sequence and a condition with cued task sequence. In a multi-tasking environment, participants chose the task order while the task requirement of the not-yet-performed task remained the same. This task preview allowed participants to work on the previously non-chosen items in parallel and resulted in faster responses and fewer errors in task switch trials than in task repetition trials. The free-choice group profited more from this task preview than the cued group when considering local performance measures. Nevertheless, the free-choice group invested more effort than the cued group when considering global measures. Thus, self-organization in task scheduling seems to be effortful even in conditions in which it is beneficiary for task processing. In a second experiment, we reduced the possibility of task preview for the not-yet-performed tasks in order to hinder efficient self-organization. Here neither local nor global measures revealed substantial differences between the free-choice and a cued task sequence condition. Based on the results of both experiments, we suggest that global assessment of effort in addition to local performance measures might be a useful tool for multitasking research.

Fatigue does not conjointly alter postural and cognitive performance when standing in a shooting position under dual-task conditions.

PubMed

Bermejo, José Luis; García-Massó, Xavier; Paillard, Thierry; Noé, Frédéric

2018-02-01

This study investigated the effects of fatigue on balance control and cognitive performance in a standing shooting position. Nineteen soldiers were asked to stand while holding a rifle (single task - ST). They also had to perform this postural task while simultaneously completing a cognitive task (dual task - DT). Both the ST and DT were performed in pre- and post-fatigue conditions. In pre-fatigue, participants achieved better balance control in the DT than in the ST, thus suggesting that the increased cognitive activity associated with the DT improves balance control by shifting the attentional focus away from a highly automatised activity. In post-fatigue, balance control was degraded in both the ST and DT, while reaction time was enhanced in the first minutes following the fatiguing exercise without affecting the accuracy of response in the cognitive task, which highlights the relative independent effects of fatigue on balance control and cognitive performance.

Temporal Prediction Errors Affect Short-Term Memory Scanning Response Time.

PubMed

Limongi, Roberto; Silva, Angélica M

2016-11-01

The Sternberg short-term memory scanning task has been used to unveil cognitive operations involved in time perception. Participants produce time intervals during the task, and the researcher explores how task performance affects interval production - where time estimation error is the dependent variable of interest. The perspective of predictive behavior regards time estimation error as a temporal prediction error (PE), an independent variable that controls cognition, behavior, and learning. Based on this perspective, we investigated whether temporal PEs affect short-term memory scanning. Participants performed temporal predictions while they maintained information in memory. Model inference revealed that PEs affected memory scanning response time independently of the memory-set size effect. We discuss the results within the context of formal and mechanistic models of short-term memory scanning and predictive coding, a Bayes-based theory of brain function. We state the hypothesis that our finding could be associated with weak frontostriatal connections and weak striatal activity.

A Multifaceted Approach to Investigating Pre-Task Planning Effects on Paired Oral Test Performance

ERIC Educational Resources Information Center

Nitta, Ryo; Nakatsuhara, Fumiyo

2014-01-01

Despite the growing popularity of paired format speaking assessments, the effects of pre-task planning time on performance in these formats are not yet well understood. For example, some studies have revealed the benefits of planning but others have not. Using a multifaceted approach including analysis of the process of speaking performance, the…

Reverse alignment "mirror image" visualization as a laparoscopic training tool improves task performance.

PubMed

Dunnican, Ward J; Singh, T Paul; Ata, Ashar; Bendana, Emma E; Conlee, Thomas D; Dolce, Charles J; Ramakrishnan, Rakesh

2010-06-01

Reverse alignment (mirror image) visualization is a disconcerting situation occasionally faced during laparoscopic operations. This occurs when the camera faces back at the surgeon in the opposite direction from which the surgeon's body and instruments are facing. Most surgeons will attempt to optimize trocar and camera placement to avoid this situation. The authors' objective was to determine whether the intentional use of reverse alignment visualization during laparoscopic training would improve performance. A standard box trainer was configured for reverse alignment, and 34 medical students and junior surgical residents were randomized to train with either forward alignment (DIRECT) or reverse alignment (MIRROR) visualization. Enrollees were tested on both modalities before and after a 4-week structured training program specific to their modality. Student's t test was used to determine differences in task performance between the 2 groups. Twenty-one participants completed the study (10 DIRECT, 11 MIRROR). There were no significant differences in performance time between DIRECT or MIRROR participants during forward or reverse alignment initial testing. At final testing, DIRECT participants had improved times only in forward alignment performance; they demonstrated no significant improvement in reverse alignment performance. MIRROR participants had significant time improvement in both forward and reverse alignment performance at final testing. Reverse alignment imaging for laparoscopic training improves task performance for both reverse alignment and forward alignment tasks. This may be translated into improved performance in the operating room when faced with reverse alignment situations. Minimal lab training can account for drastic adaptation to this environment.

The effect of ergonomic laparoscopic tool handle design on performance and efficiency.

PubMed

Tung, Kryztopher D; Shorti, Rami M; Downey, Earl C; Bloswick, Donald S; Merryweather, Andrew S

2015-09-01

Many factors can affect a surgeon's performance in the operating room; these may include surgeon comfort, ergonomics of tool handle design, and fatigue. A laparoscopic tool handle designed with ergonomic considerations (pistol grip) was tested against a current market tool with a traditional pinch grip handle. The goal of this study is to quantify the impact ergonomic design considerations which have on surgeon performance. We hypothesized that there will be measurable differences between the efficiency while performing FLS surgical trainer tasks when using both tool handle designs in three categories: time to completion, technical skill, and subjective user ratings. The pistol grip incorporates an ergonomic interface intended to reduce contact stress points on the hand and fingers, promote a more neutral operating wrist posture, and reduce hand tremor and fatigue. The traditional pinch grip is a laparoscopic tool developed by Stryker Inc. widely used during minimal invasive surgery. Twenty-three (13 M, 10 F) participants with no existing upper extremity musculoskeletal disorders or experience performing laparoscopic procedures were selected to perform in this study. During a training session prior to testing, participants performed practice trials in a SAGES FLS trainer with both tools. During data collection, participants performed three evaluation tasks using both handle designs (order was randomized, and each trial completed three times). The tasks consisted of FLS peg transfer, cutting, and suturing tasks. Feedback from test participants indicated that they significantly preferred the ergonomic pistol grip in every category (p < 0.05); most notably, participants experienced greater degrees of discomfort in their hands after using the pinch grip tool. Furthermore, participants completed cutting and peg transfer tasks in a shorter time duration (p < 0.05) with the pistol grip than with the pinch grip design; there was no significant difference between completion times for the suturing task. Finally, there was no significant interaction between tool type and errors made during trials. There was a significant preference for as well as lower pain experienced during use of the pistol grip tool as seen from the survey feedback. Both evaluation tasks (cutting and peg transfer) were also completed significantly faster with the pistol grip tool. Finally, due to the high degree of variability in the error data, it was not possible to draw any meaningful conclusions about the effect of tool design on the number or degree of errors made.

The interacting effect of cognitive and motor task demands on performance of gait, balance and cognition in young adults.

PubMed

Szturm, Tony; Maharjan, Pramila; Marotta, Jonathan J; Shay, Barbara; Shrestha, Shiva; Sakhalkar, Vedant

2013-09-01

Mobility limitations and cognitive impairments, each common with aging, reduce levels of physical and mental activity, are prognostic of future adverse health events, and are associated with an increased fall risk. The purpose of this study was to examine whether divided attention during walking at a constant speed would decrease locomotor rhythm, stability, and cognitive performance. Young healthy participants (n=20) performed a visuo-spatial cognitive task in sitting and while treadmill walking at 2 speeds (0.7 and 1.0 m/s).Treadmill speed had a significant effect on temporal gait variables and ML-COP excursion. Cognitive load did not have a significant effect on average temporal gait variables or COP excursion, but variation of gait variables increased during dual-task walking. ML and AP trunk motion was found to decrease during dual-task walking. There was a significant decrease in cognitive performance (success rate, response time and movement time) while walking, but no effect due to treadmill speed. In conclusion walking speed is an important variable to be controlled in studies that are designed to examine effects of concurrent cognitive tasks on locomotor rhythm, pacing and stability. Divided attention during walking at a constant speed did result in decreased performance of a visuo-spatial cognitive task and an increased variability in locomotor rhythm. Copyright © 2013 Elsevier B.V. All rights reserved.

The sensitivity of a virtual reality task to planning and prospective memory impairments: group differences and the efficacy of periodic alerts on performance.

PubMed

Sweeney, Siobhan; Kersel, Denyse; Morris, Robin G; Manly, Tom; Evans, Jonathan J

2010-04-01

Executive functions have been argued to be the most vulnerable to brain injury. In providing an analogue of everyday situations amenable to control and management virtual reality (VR) may offer better insights into planning deficits consequent upon brain injury. Here 17 participants with a non-progressive brain injury and reported executive difficulties in everyday life were asked to perform a VR task (working in a furniture storage unit) that emphasised planning, rule following and prospective memory tasks. When compared with an age and IQ-matched control group, the patients were significantly poorer in terms of their strategy, their time-based prospective memory, the overall time required and their propensity to break rules. An examination of sensitivity and specificity of the VR task to group membership (brain-injured or control) showed that, with specificity set at maximum, sensitivity was only modest (at just over 50%). A second component to the study investigated whether the patients' performance could be improved by periodic auditory alerts. Previous studies have demonstrated that such cues can improve performance on laboratory tests, executive tests and everyday prospective memory tasks. Here, no significant changes in performance were detected. Potential reasons for this finding are discussed, including symptom severity and differences in the tasks employed in previous studies.

Lifespan development of the bilateral deficit in a simple reaction time task.

PubMed

Vieluf, Solveig; Aschersleben, Gisa; Panzer, Stefan

2017-04-01

Performing an action at a maximum speed or with a maximum strength simultaneously with two limbs leads to a lower performance than the sum of unimanual performances. This phenomenon is known as bilateral deficit. There is some evidence that the bilateral deficit changes over the lifespan, in a way that children and older adults show lower deficits than young adults. Inverse developmental changes of childrens' and older adults' brain structures connecting both hemispheres, i.e., the corpus callosum, might importantly contribute to this phenomenon. The seemingly similar developments have been observed with different experimental protocols in the different age groups, respectively. To test for similarities and differences in changes of the bilateral deficit at critical periods of the lifespan development of bimanual actions, children, young adults, and older adults performed a simple reaction time task uni- and bimanually. Reaction times and the resulting bilateral deficit, as well as reaction time variability were analyzed. As expected, reaction times were different for the young adults between the uni- and the bimanual task. Children and older adults performed both conditions with similar reaction times. However, a difference in the direction of the %bilateral deficit occurred between the two age groups. The findings demonstrated an absence of the bilateral deficit for children, but not for younger and older adults.

Upper limb performance and the structuring of joint movement in teenagers with cerebral palsy: the reciprocal role of task demands and action capabilities.

PubMed

Figueiredo, Priscilla Rezende Pereira; Silva, Paula Lanna; Avelar, Bruna Silva; da Fonseca, Sérgio Teixeira; Bootsma, Reinoud J; Mancini, Marisa Cotta

2015-04-01

Individuals with unilateral cerebral palsy (CP) demonstrate reduced performance in upper limb tasks compared to typically developing (TD) peers. We examined whether task conditions modify differences between teenagers with and without CP during a reciprocal aiming task. Twenty teenagers (nine CP and 11 TD) moved a pointer between two targets as fast as possible without missing a target. Task conditions were manipulated by changing the targets' size, by modifying the inertial properties of the pointer and by varying the upper limb used to perform the task (preferred/non-affected and non-preferred/affected upper limbs). While compared to TD peers, CP teenagers exhibited lower performance (longer movement times). Such differences were attenuated when the task was performed with the preferred upper limb and when accuracy requirements were less stringent. CP teenagers were not differentially affected by the pointer inertia manipulation. Task conditions not only affected performance but also joint kinematics. CP teenagers revealed less movement at the elbow and more movement at the shoulder when performing the task with their less skilled upper limb. However, both CP and TD teenagers demonstrated a larger contribution of trunk movement when facing more challenging task conditions. The overall pattern of results indicated that the joint kinematics employed by individuals with unilateral CP constituted adaptive responses to task requirements. Thus, the explanation of the effects of unilateral CP on upper limb behavior needs to go beyond a context-indifferent manifestation of the brain injury to include the interaction between task demands and action capabilities.

Influence of drive and timing mechanisms on breathing pattern and ventilation during mental task performance.

PubMed

Wientjes, C J; Grossman, P; Gaillard, A W

1998-09-01

Assessment of multiple respiratory measures may provide insight into how behavioral demands affect the breathing pattern. This is illustrated by data from a study among 44 subjects, in which tidal volume, respiration rate, minute ventilation and indices of central drive and timing mechanisms were assessed via inductive plethysmography, in addition to end-tidal PCO2. After a baseline, three conditions of a memory comparison task were presented. The first two conditions differed only with regard to the presence or absence of feedback of performance (NFB and FB). In the third 'all-or-nothing' (AON) condition, subjects only received a monetary bonus, if their performance exceeded that of the previous two conditions. Minute ventilation increased from baseline to all task conditions, and from NFB and FB to AON. Respiration rate increased in all task conditions, but there were no differences between task conditions. Tidal volume decreased during NFB, but was equal to baseline during FB and AON. Of the respiratory control indices, inspiratory flow rate covaried much more closely with minute ventilation than duty cycle. The task performance induced a minor degree of hyperventilation. The discussion focusses on how behavioral demands affect respiratory control processes to produce alterations in breathing pattern and ventilation.

Adjustable control station with movable monitors and cameras for viewing systems in robotics and teleoperations

NASA Technical Reports Server (NTRS)

Diner, Daniel B. (Inventor)

1994-01-01

Real-time video presentations are provided in the field of operator-supervised automation and teleoperation, particularly in control stations having movable cameras for optimal viewing of a region of interest in robotics and teleoperations for performing different types of tasks. Movable monitors to match the corresponding camera orientations (pan, tilt, and roll) are provided in order to match the coordinate systems of all the monitors to the operator internal coordinate system. Automated control of the arrangement of cameras and monitors, and of the configuration of system parameters, is provided for optimal viewing and performance of each type of task for each operator since operators have different individual characteristics. The optimal viewing arrangement and system parameter configuration is determined and stored for each operator in performing each of many types of tasks in order to aid the automation of setting up optimal arrangements and configurations for successive tasks in real time. Factors in determining what is optimal include the operator's ability to use hand-controllers for each type of task. Robot joint locations, forces and torques are used, as well as the operator's identity, to identify the current type of task being performed in order to call up a stored optimal viewing arrangement and system parameter configuration.

Time Estimation and Performance on Reproduction Tasks in Subtypes of Children with Attention Deficit Hyperactivity Disorder

ERIC Educational Resources Information Center

Salas, Carmen C.; Bauermeister, Jose J.; Barkley, Russell A.; Martinez, Jose V.; Cumba, Eduardo; Ramirez, Rafael R.; Reina, Graciela; Matos, Maribel

2005-01-01

This study compared Hispanic children (ages 7 to 11) with combined type (CT, n = 33) and inattentive type (IT, n = 21) attention deficit hyperactivity disorder (ADHD) and a control group (n = 25) on time-estimation and time-reproduction tasks. The ADHD groups showed larger errors in time reproduction but not in time estimation than the control…

Novel Analog For Muscle Deconditioning

NASA Technical Reports Server (NTRS)

Ploutz-Snyder, Lori; Ryder, Jeff; Buxton, Roxanne; Redd, Elizabeth; Scott-Pandorf, Melissa; Hackney, Kyle; Fiedler, James; Bloomberg, Jacob

2010-01-01

Existing models of muscle deconditioning are cumbersome and expensive (ex: bedrest). We propose a new model utilizing a weighted suit to manipulate strength, power or endurance (function) relative to body weight (BW). Methods: 20 subjects performed 7 occupational astronaut tasks while wearing a suit weighted with 0-120% of BW. Models of the full relationship between muscle function/BW and task completion time were developed using fractional polynomial regression and verified by the addition of pre- and post-flight astronaut performance data using the same tasks. Spline regression was used to identify muscle function thresholds below which task performance was impaired. Results: Thresholds of performance decline were identified for each task. Seated egress & walk (most difficult task) showed thresholds of: leg press (LP) isometric peak force/BW of 18 N/kg, LP power/BW of 18 W/kg, LP work/ BW of 79 J/kg, knee extension (KE) isokinetic/BW of 6 Nm/Kg and KE torque/BW of 1.9 Nm/kg. Conclusions: Laboratory manipulation of strength / BW has promise as an appropriate analog for spaceflight-induced loss of muscle function for predicting occupational task performance and establishing operationally relevant exercise targets.

Novel Analog For Muscle Deconditioning

NASA Technical Reports Server (NTRS)

Ploutz-Snyder, Lori; Ryder, Jeff; Buxton, Roxanne; Redd. Elizabeth; Scott-Pandorf, Melissa; Hackney, Kyle; Fiedler, James; Ploutz-Snyder, Robert; Bloomberg, Jacob

2011-01-01

Existing models (such as bed rest) of muscle deconditioning are cumbersome and expensive. We propose a new model utilizing a weighted suit to manipulate strength, power, or endurance (function) relative to body weight (BW). Methods: 20 subjects performed 7 occupational astronaut tasks while wearing a suit weighted with 0-120% of BW. Models of the full relationship between muscle function/BW and task completion time were developed using fractional polynomial regression and verified by the addition of pre-and postflightastronaut performance data for the same tasks. Splineregression was used to identify muscle function thresholds below which task performance was impaired. Results: Thresholds of performance decline were identified for each task. Seated egress & walk (most difficult task) showed thresholds of leg press (LP) isometric peak force/BW of 18 N/kg, LP power/BW of 18 W/kg, LP work/BW of 79 J/kg, isokineticknee extension (KE)/BW of 6 Nm/kg, and KE torque/BW of 1.9 Nm/kg.Conclusions: Laboratory manipulation of relative strength has promise as an appropriate analog for spaceflight-induced loss of muscle function, for predicting occupational task performance and establishing operationally relevant strength thresholds.

Attention and working memory in elderly: the influence of a distracting environment.

PubMed

Rodrigues, Pedro F S; Pandeirada, Josefa N S

2015-02-01

The present work investigated the effect of a distracting environment in the performance of attentional and working memory (WM) tasks in elderly participants. To this end, forty elderly performed two attentional tasks (simple reaction time and go/no-go tasks), and three WM tasks (arithmetic, memory for digits and sequences of letters and numbers). Each participant performed the tasks in a distracting and a non-distracting environment, with an interval of 14-21 days between sessions. The results revealed better performance in the attentional tasks when these were done in the non-distracting environment, as compared to when they were done in the distracting environment. Specifically, participants provided more accurate responses, fewer false alarms and omissions when responding in the non-distracting environment than when responding in the distracting environment. Participants were also faster at providing correct responses in the go/no-go task when it was performed in the non-distracting environment. As for the memory tasks, the effect of type of environment was significant only in the memory for digits in a forward direction task. Our data suggest the need to consider the potential damaging consequences of distracting environments when the elderly have to perform tasks that demand their attention. Specific examples of such situations are presented in the discussion (e.g., distracting effect of environment on medical and on psychological evaluations).

"How To" Videos Improve Residents Performance of Essential Perioperative Electronic Medical Records and Clinical Tasks.

PubMed

Zoghbi, Veronica; Caskey, Robert C; Dumon, Kristoffel R; Soegaard Ballester, Jacqueline M; Brooks, Ari D; Morris, Jon B; Dempsey, Daniel T

The ability to use electronic medical records (EMR) is an essential skill for surgical residents. However, frustration and anxiety surrounding EMR tasks may detract from clinical performance. We created a series of brief, 1-3 minutes "how to" videos demonstrating 7 key perioperative EMR tasks: booking OR cases, placing preprocedure orders, ordering negative-pressure wound dressing supplies, updating day-of-surgery history and physical notes, writing brief operative notes, discharging patients from the postanesthesia care unit, and checking vital signs. Additionally, we used "Cutting Insights"-a locally developed responsive mobile application for surgical trainee education-as a platform for providing interns with easy access to these videos. We hypothesized that exposure to these videos would lead to increased resident efficiency and confidence in performing essential perioperative tasks, ultimately leading to improved clinical performance. Eleven surgery interns participated in this initiative. Before watching the "how to" videos, each intern was timed performing the aforementioned 7 key perioperative EMR tasks. They also underwent a simulated perioperative emergency requiring the performance of 3 of these EMR tasks in conjunction with 5 other required interventions (including notifying the chief resident, the anesthesia team, and the OR coordinator; and ordering fluid boluses, appropriate laboratories, and blood products). These simulations were scored on a scale from 0 to 8. The interns were then directed to watch the videos. Two days later, their times for performing the 7 tasks and their scores for a similar perioperative emergency simulation were once again recorded. Before and after watching the videos, participants were surveyed to assess their confidence in performing each EMR task using a 5-point Likert scale. We also elicited their opinions of the videos and web-based mobile application using a 5-point scale. Statistical analyses to assess for statistical significance (p ≤ 0.05) were conducted using paired t-test for parametric variables and a Wilcoxon matched-pair test for nonparametric variables. Hospital of the University of Pennsylvania, Philadelphia, PA (a quaternary teaching hospital within the University of Pennsylvania Health System). Eleven out of 15 interns (12 entered and 11 completed the study) from our categorical and preliminary general surgery residency programs during the 2016 academic year. Before exposure to the brief "how to" videos, 6 of 11 interns were unable to complete all 7 EMR tasks; after exposure, all 11 interns were able to complete all 7 EMR tasks. Moreover, interns' times for each task improved following exposure. Interns self-reported improved confidence in booking an OR case (4 ± 0.9 vs. 4.7 ± 0.6, p = 0.05), ordering negative-pressure wound therapy supplies (3.1 ± 1.6 vs. 4.5 ± 0.7, p < 0.05), writing a brief operative note (3.7 ± 1.2 vs. 4.6 ± 0.7, p = 0.05), discharging patients from the postanesthesia care unit (3.3 ± 1.0 vs. 4.4 ± 0.8, p < 0.05), checking vital signs (2.5 ± 1.4 vs. 4.5 ± 0.8, p ≤ 0.01), and performing necessary EMR tasks during an emergency situation (2.4 ± 0.8 vs. 4.6 ± 0.7, p ≤ 0.0001). Participants also demonstrated a significant improvement in average clinical score on the emergency simulations (5.2 ± 1.7 vs. 6.6 ± 0.9, p < 0.05). Interns' opinions of the videos and the mobile phone application were favorable. In our group of 11 surgery interns, exposure to a series of short "how to" videos led to increased confidence and shortened times in performing 7 essential EMR tasks. Additionally, during a simulated perioperative emergency, EMR tasks were performed significantly faster. Clinical performance also improved significantly following exposure to the videos. This just-in-time educational intervention could improve workflow efficiency and clinical performance, both of which may ultimately enhance perioperative patient safety. Copyright © 2017. Published by Elsevier Inc.

A Scheduling Algorithm for Replicated Real-Time Tasks

NASA Technical Reports Server (NTRS)

Yu, Albert C.; Lin, Kwei-Jay

1991-01-01

We present an algorithm for scheduling real-time periodic tasks on a multiprocessor system under fault-tolerant requirement. Our approach incorporates both the redundancy and masking technique and the imprecise computation model. Since the tasks in hard real-time systems have stringent timing constraints, the redundancy and masking technique are more appropriate than the rollback techniques which usually require extra time for error recovery. The imprecise computation model provides flexible functionality by trading off the quality of the result produced by a task with the amount of processing time required to produce it. It therefore permits the performance of a real-time system to degrade gracefully. We evaluate the algorithm by stochastic analysis and Monte Carlo simulations. The results show that the algorithm is resilient under hardware failures.

Time-on-task decrement in vigilance is modulated by inter-individual vulnerability to homeostatic sleep pressure manipulation

PubMed Central

Maire, Micheline; Reichert, Carolin F.; Gabel, Virginie; Viola, Antoine U.; Krebs, Julia; Strobel, Werner; Landolt, Hans-Peter; Bachmann, Valérie; Cajochen, Christian; Schmidt, Christina

2014-01-01

Under sleep loss, vigilance is reduced and attentional failures emerge progressively. It becomes difficult to maintain stable performance over time, leading to growing performance variability (i.e., state instability) in an individual and among subjects. Task duration plays a major role in the maintenance of stable vigilance levels, such that the longer the task, the more likely state instability will be observed. Vulnerability to sleep-loss-dependent performance decrements is highly individual and is also modulated by a polymorphism in the human clock gene PERIOD3 (PER3). By combining two different protocols, we manipulated sleep-wake history by once extending wakefulness for 40 h (high sleep pressure condition) and once by imposing a short sleep-wake cycle by alternating 160 min of wakefulness and 80 min naps (low sleep pressure condition) in a within-subject design. We observed that homozygous carriers of the long repeat allele of PER3 (PER35/5) experienced a greater time-on-task dependent performance decrement (i.e., a steeper increase in the number of lapses) in the Psychomotor Vigilance Task compared to the carriers of the short repeat allele (PER34/4). These genotype-dependent effects disappeared under low sleep pressure conditions, and neither motivation, nor perceived effort accounted for these differences. Our data thus suggest that greater sleep-loss related attentional vulnerability based on the PER3 polymorphism is mirrored by a greater state instability under extended wakefulness in the short compared to the long allele carriers. Our results undermine the importance of time-on-task related aspects when investigating inter-individual differences in sleep loss-induced behavioral vulnerability. PMID:24639634

Man-machine cooperation in advanced teleoperation

NASA Technical Reports Server (NTRS)

Fiorini, Paolo; Das, Hari; Lee, Sukhan

1993-01-01

Teleoperation experiments at JPL have shown that advanced features in a telerobotic system are a necessary condition for good results, but that they are not sufficient to assure consistently good performance by the operators. Two or three operators are normally used during training and experiments to maintain the desired performance. An alternative to this multi-operator control station is a man-machine interface embedding computer programs that can perform some of the operator's functions. In this paper we present our first experiments with these concepts, in which we focused on the areas of real-time task monitoring and interactive path planning. In the first case, when performing a known task, the operator has an automatic aid for setting control parameters and camera views. In the second case, an interactive path planner will rank different path alternatives so that the operator will make the correct control decision. The monitoring function has been implemented with a neural network doing the real-time task segmentation. The interactive path planner was implemented for redundant manipulators to specify arm configurations across the desired path and satisfy geometric, task, and performance constraints.

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.

Integrated command, control, communication and computation system design study. Summary of tasks performed

NASA Technical Reports Server (NTRS)

1982-01-01

A summary of tasks performed on an integrated command, control, communication, and computation system design study is given. The Tracking and Data Relay Satellite System command and control system study, an automated real-time operations study, and image processing work are discussed.

New paradigm for task switching strategies while performing multiple tasks: entropy and symbolic dynamics analysis of voluntary patterns.

PubMed

Guastello, Stephen J; Gorin, Hillary; Huschen, Samuel; Peters, Natalie E; Fabisch, Megan; Poston, Kirsten

2012-10-01

It has become well established in laboratory experiments that switching tasks, perhaps due to interruptions at work, incur costs in response time to complete the next task. Conditions are also known that exaggerate or lessen the switching costs. Although switching costs can contribute to fatigue, task switching can also be an adaptive response to fatigue. The present study introduces a new research paradigm for studying the emergence of voluntary task switching regimes, self-organizing processes therein, and the possibly conflicting roles of switching costs and minimum entropy. Fifty-four undergraduates performed 7 different computer-based cognitive tasks producing sets of 49 responses under instructional conditions requiring task quotas or no quotas. The sequences of task choices were analyzed using orbital decomposition to extract pattern types and lengths, which were then classified and compared with regard to Shannon entropy, topological entropy, number of task switches involved, and overall performance. Results indicated that similar but different patterns were generated under the two instructional conditions, and better performance was associated with lower topological entropy. Both entropy metrics were associated with the amount of voluntary task switching. Future research should explore conditions affecting the trade-off between switching costs and entropy, levels of automaticity between task elements, and the role of voluntary switching regimes on fatigue.

Sensorimotor Rhythm BCI with Simultaneous High Definition-Transcranial Direct Current Stimulation Alters Task Performance.

PubMed

Baxter, Bryan S; Edelman, Bradley J; Nesbitt, Nicholas; He, Bin

Transcranial direct current stimulation (tDCS) has been used to alter the excitability of neurons within the cerebral cortex. Improvements in motor learning have been found in multiple studies when tDCS was applied to the motor cortex before or during task learning. The motor cortex is also active during the performance of motor imagination, a cognitive task during which a person imagines, but does not execute, a movement. Motor imagery can be used with noninvasive brain computer interfaces (BCIs) to control virtual objects in up to three dimensions, but to master control of such devices requires long training times. To evaluate the effect of high-definition tDCS on the performance and underlying electrophysiology of motor imagery based BCI. We utilize high-definition tDCS to investigate the effect of stimulation on motor imagery-based BCI performance across and within sessions over multiple training days. We report a decreased time-to-hit with anodal stimulation both within and across sessions. We also found differing electrophysiological changes of the stimulated sensorimotor cortex during online BCI task performance for left vs. right trials. Cathodal stimulation led to a decrease in alpha and beta band power during task performance compared to sham stimulation for right hand imagination trials. These results suggest that unilateral tDCS over the sensorimotor motor cortex differentially affects cortical areas based on task specific neural activation. Copyright © 2016 Elsevier Inc. All rights reserved.

A multilevel modeling approach to examining individual differences in skill acquisition for a computer-based task.

PubMed

Nair, Sankaran N; Czaja, Sara J; Sharit, Joseph

2007-06-01

This article explores the role of age, cognitive abilities, prior experience, and knowledge in skill acquisition for a computer-based simulated customer service task. Fifty-two participants aged 50-80 performed the task over 4 consecutive days following training. They also completed a battery that assessed prior computer experience and cognitive abilities. The data indicated that overall quality and efficiency of performance improved with practice. The predictors of initial level of performance and rate of change in performance varied according to the performance parameter assessed. Age and fluid intelligence predicted initial level and rate of improvement in overall quality, whereas crystallized intelligence and age predicted initial e-mail processing time, and crystallized intelligence predicted rate of change in e-mail processing time over days. We discuss the implications of these findings for the design of intervention strategies.

Effect of Ovarian Hormone Therapy on Cognition in the Aged Female Rhesus Macaque.

PubMed

Kohama, Steven G; Renner, Lauren; Landauer, Noelle; Weiss, Alison R; Urbanski, Henryk F; Park, Byung; Voytko, Mary Lou; Neuringer, Martha

2016-10-05

Studies of the effect of hormone therapy on cognitive function in menopausal women have been equivocal, in part due to differences in the type and timing of hormone treatment. Here we cognitively tested aged female rhesus macaques on (1) the delayed response task of spatial working memory, (2) a visuospatial attention task that measured spatially and temporally cued reaction times, and (3) a simple reaction time task as a control for motor speed. After task acquisition, animals were ovariectomized (OVX). Their performance was compared with intact controls for 2 months, at which time no group differences were found. The OVX animals were then assigned to treatment with either a subcutaneous sham implant (OVX), 17-β estradiol (E) implant (OVX+E) or E implant plus cyclic oral progesterone (OVX+EP). All groups were then tested repeatedly over 12 months. The OVX+E animals performed significantly better on the delayed response task than all of the other groups for much of the 12 month testing period. The OVX+EP animals also showed improved performance in the delayed response task, but only at 30 s delays and with performance levels below that of OVX+E animals. The OVX+E animals also performed significantly better in the visuospatial attention task, particularly in the most challenging invalid cue condition; this difference also was maintained across the 12 month testing period. Simple reaction time was not affected by hormonal manipulation. These data demonstrate that chronic, continuous administration of E can exert multiple beneficial cognitive effects in aged, OVX rhesus macaque females. Hormone therapy after menopause is controversial. We tested the effects of hormone replacement in aged rhesus macaques, soon after surgically-induced menopause [ovariectomy (OVX)], on tests of memory and attention. Untreated ovarian-intact and OVX animals were compared with OVX animals receiving estradiol (E) alone or E with progesterone (P). E was administered in a continuous fashion via subcutaneous implant, whereas P was administered orally in a cyclic fashion. On both tests, E-treated animals performed better than the other 3 experimental groups across 1 year of treatment. Thus, in this monkey model, chronic E administered soon after the loss of ovarian hormones had long-term benefits for cognitive function. Copyright © 2016 the authors 0270-6474/16/3610416-09$15.00/0.

An on-road assessment of cognitive distraction: impacts on drivers' visual behavior and braking performance.

PubMed

Harbluk, Joanne L; Noy, Y Ian; Trbovich, Patricia L; Eizenman, Moshe

2007-03-01

In this on-road experiment, drivers performed demanding cognitive tasks while driving in city traffic. All task interactions were carried out in hands-free mode so that the 21 drivers were not required to take their visual attention away from the road or to manually interact with a device inside the vehicle. Visual behavior and vehicle control were assessed while they drove an 8 km city route under three conditions: no additional task, easy cognitive task and difficult cognitive task. Changes in visual behavior were most apparent when performance between the No Task and Difficult Task conditions were compared. When looking outside of the vehicle, drivers spent more time looking centrally ahead and spent less time looking to the areas in the periphery. Drivers also reduced their visual monitoring of the instruments and mirrors, with some drivers abandoning these tasks entirely. When approaching and driving through intersections, drivers made fewer inspection glances to traffic lights compared to the No Task condition and their scanning of intersection areas to the right was also reduced. Vehicle control was also affected; during the most difficult cognitive tasks there were more occurrences of hard braking. Although hands-free designs for telematics devices are intended to reduce or eliminate the distraction arising from manual operation of these units, the potential for cognitive distraction associated with their use must also be considered and appropriately assessed. These changes are captured in measures of drivers' visual behavior.

Body sway adaptation to addition but not withdrawal of stabilizing visual information is delayed by a concurrent cognitive task.

PubMed

Honeine, Jean-Louis; Crisafulli, Oscar; Schieppati, Marco

2017-02-01

The aim of this study was to test the effects of a concurrent cognitive task on the promptness of the sensorimotor integration and reweighting processes following addition and withdrawal of vision. Fourteen subjects stood in tandem while vision was passively added and removed. Subjects performed a cognitive task, consisting of counting backward in steps of three, or were "mentally idle." We estimated the time intervals following addition and withdrawal of vision at which body sway began to change. We also estimated the time constant of the exponential change in body oscillation until the new level of sway was reached, consistent with the current visual state. Under the mentally idle condition, mean latency was 0.67 and 0.46 s and the mean time constant was 1.27 and 0.59 s for vision addition and withdrawal, respectively. Following addition of vision, counting backward delayed the latency by about 300 ms, without affecting the time constant. Following withdrawal, counting backward had no significant effect on either latency or time constant. The extension by counting backward of the time interval to stabilization onset on addition of vision suggests a competition for allocation of cortical resources. Conversely, the absence of cognitive task effect on the rapid onset of destabilization on vision withdrawal, and on the relevant reweighting time course, advocates the intervention of a subcortical process. Diverting attention from a challenging standing task discloses a cortical supervision on the process of sensorimotor integration of new balance-stabilizing information. A subcortical process would instead organize the response to removal of the stabilizing sensory input. NEW & NOTEWORTHY This study is the first to test the effect of an arithmetic task on the time course of balance readjustment following visual withdrawal or addition. Performing such a cognitive task increases the time delay following addition of vision but has no effect on withdrawal dynamics. This suggests that sensorimotor integration following addition of a stabilizing signal is performed at a cortical level, whereas the response to its withdrawal is "automatic" and accomplished at a subcortical level. Copyright © 2017 the American Physiological Society.