Time-on-task

Bowyer, P., Humphreys, M. and Reville, W., Arousal and recognition memory. The effects of impulsivity, caffeine and time on task. Person Individ Diff 4, 41-49, 1985. 

The Walter Reed Army Institute of Research s Department of Behavioral Biology has developed a field-deployable version of a commercial Psychomotor Vigilance Task (PVT) that has been widely used in sleep research. The software runs on handheld PDAs running the Palm Operating System (Palm OS). It is modeled after the simple reaction time task of Wilkinson and Houghton,57 as modified by Dinges and Powell.58 The Palm OS version incorporates additional stimulus, feedback, control, and data options developed by Dr. Thome. In laboratory studies, performance on the PDA task has been shown to be sensitive to time-on-task fatigue effects, sleep deprivation, and circadian variation.18 Field studies have utilized the PVT to measure the efficacy of caffeine gum as a sleep loss countermeasure. 

A second observation that cannot be explained by the lapse hypothesis is the well-documented time-on-task decrement (5,6,32,44), which refers to systematic dete-... 

PVT performance in sleepy individuals frequently shows the effects of time-on-task on lapse rates at any severity of experimental sleep deprivation (e.g., see Fig. 1). Sleep deprivation can markedly worsen this fatigue effect in PVT performance, regardless of whether the elevated sleep pressure is experimentally induced (5), or through sleep disorders such as the obstructive sleep apnea syndrome (32). Thus, cognitive performance becomes more variable with both time awake and time-on-task (44). 

Findley LJ, Suratt PM, Dinges DF. Time-on-task decrements in steer clear performance of patients with sleep apnea and narcolepsy. Sleep 1999 22 804-809. 

In other studies of sleep deprivation the adverse effects on general human performance were dependent upon time-on-task. Duration of testing was often only a few minutes in the athletic performance tests reviewed. Cognitive performance is particularly sensitive to time-on-task testing after sleep deprivation. No study has directly examined cognitive athletic performance, let alone across various time frames. Results of Reilly and Piercy (37) suggest time-on-task is an important differentiator both physically and cognitively. 

Since pemoline is intended primarily as a treatment for ADHD, its effects on vigilance have not been well established. However, Orzack et al. (60) compared 25 mg and 50 mg pemoline to 100 mg and 200 mg caffeine, 15 mg methylphenidate, and placebo on the performance of a 2-hr psychomotor task (pressing keys corresponding to visual stimuli). They found that performance deteriorated as a function of time on task under the influence of placebo, but that 50 mg pemoline, 200 mg caffeine, and 15 mg methylphenidate maintained consistent performance throughout the 2 hr. 

Nachreiner, F. (2001). Time on task effeets on safety. Journal of Human Ergology, 30, 97-102. 

McGregor, D. K., Stem, J. A. (1996). Time on task and blink effects on saccade duration. Ergonomics, 39, 649-660. 

In general, performance measures have a more specific and diiect relation to a presumed psychological concept than physiological measures. Increases in reaction time due to an increase in task difficulty are explained in terms of an increase in processing time. Also here aspecific effects (e.g., changes in motivation, time of day, time on task, etc.) may confound this relation, although they may be controlled or corrected. 

What can these systems tell us about cognitive processes in general, and "mental fatigue," an admittedly vague concept, in particular Everyone knows when they feel fatigued, but an objective measure of this construct has yet to be developed. We will assume that work-induced fetigue develops as a function of time-on-task, and that the rate at which fatigue effects appear is a function of the complex interaction between a variety of both subject and task variables. 

Bahill and Stark (1975) and Robinson (1981) both report additional time-on-task effects. The frequency o/g/wsatfes (saccades terminating in a dow drifting eye movement) increases with time-on-task. Inefficient initial saccades requiring that another saccade be produced in order to move the eyes to a target location (a phenomenon known as double saccading) are also more frequent dur-... 

For this reason, Stem, Boyer, Schroeder, Touehstone, and Stoliarov(1996)have suggested that aspects ofblinkingotherthan rate may be more diagnostic of time-on-task effects. For example, blink closure duration (or the period of time during which the pupil is obscured the lid during a blink) demonstrates significant time-... 

One such issue concerns whether fatigue evolves as a linear (or monotonic) function of time-on-task or is better described as producing intermittent periods of impaired performance that may increase in frequency and duration as a function of time-on-task. There is some empirical support for the latter position. In subjectpaced tasks, periods characterized by unusually slow responses (performance blocks defined as local response latencies deviating from the mean by more than two standard deviations) increase in both frequency and duration as a function of time-on-task (Bills, 1931). Bills reported that sleep loss and sub-... 

Stem, J. A., Boyer, D. J., Sehroeder, D., Touchstone, M., Stoharov, N. (1994). Blinks, saccades, and fixation pauses during vigilance task performance I. Time-on-task. Z)07 /K4A i4A/9426. FAA. Office of Aviation Me cine. 

Are students working hard How long do students stick with difficult problems Time on task persistence or patterns Electronic homework records... 

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