Effect of time and space uncertainty on a vigilance task

Two groups, each of 12 Ss, were instructed to detect increments in light level from displays of one or five lights. Signals appeared in regular and in irregular intervals. The display was flashed on simultaneously for 0.8 sec every 3.2 sec. Signal detection was superior with a display of one light than with a display of five lights. For two extreme response criteria, there was a decrement of false alarms and an increment of beta during a run. These changes were not dependent upon time and spatial uncertainty. There were no systematic changes in correct detections and d’ during a run. No difference was found between central and peripheral light positions. Correlation of measures was also examined.     

The effects of music and task difficulty on performance at a visual vigilance task

Forty subjects performed a visual vigilance task in music or noise and when the task was difficult or easy. Response measures taken were: correct detections, commission errors, detection latencies and d' values. For the difficult version of the task a significant increase in detection latencies was found which music prevented. Broadly similar findings were obtained for correct detections. The results are compared with other studies of detection latency and task difficulty and are discussed in terms of arousal.     

Internal-external locus of control and performance on a vigilance task.

Previous studies have demonstrated there are large individual differences in subjects' ability to perform on vigilance or watch-keeping tasks. This study used Rotter's Internal-External (I-E) Locus of Control Scale to resolve some of the variance attributed to individual differences and tested the hypothesis that the internally controlled person is a better monitor on a vigilance task than an externally controlled person. There were 64 subjects who performed a visual watch-keeping task for a 1-hr. period. The results indicated that the external subjects made significantly more incorrect responses and missed significantly more signals during the entire task. The internal-external dimension was effective in differentiating performance on a vigilance task.     

Errors of commission as a function of age and temperament in a type of vigilance task

Forty subjects monitored a 40 min. series of 10-sec. intervals containing digits (spoken at the rate of 1 per sec.), each followed by 10-sec. silence. The task was to report whether or not three consecutive and different odd digits occurred. Responses were forced. The results showed that there was no correlation between either age or temperament and the number of correct detections made. Older subjects, however, made more errors of commission, and were less able to distinguish wanted from unwanted events. The younger and introverted subjects appeared to be more cautious. The data is discussed in terms of the arousal theory of vigilance performance.     

Effects of noise on sensitivity of introverts and extraverts to signals in a vigilance task

Forty Ss, previously classified as introverts or extraverts on the basis of scores on the Eysenck Personality Inventory, performed a visual vigilance task while being stimulated with noise at an intensity level of either 65 or 85 dB. Introverts given noise of 65 dB intensity showed an improvement in detection rate across trials, whereas introverts given noise of 85 dB intensity showed a decline in detection rate. Extraverts responded to noise of 65 dB intensity with a slight decrease in detection rate, but showed an improvement in detection over trials when noise of 85 dB intensity was given. When noise of the lower intensity was given, introverts showed greater sensitivity to signals than extraverts. When noise of the higher intensity was given, introverts and extraverts were equal in sensitivity. The results are discussed in terms of a hypothesized relationship between stimulation and arousal, with E-I as a moderator variable.     

The sensitivity of a palm-based psychomotor vigilance task to severe sleep loss

In this study, we evaluated the sensitivity of a 5-min personal digital assistant-psychomotor vigilance test (PDA-PVT) to severe sleep loss. Twenty-one participants completed a 10-min PVT-192 and a 5-min PDA-PVT at two hourly intervals during 62 h of sustained wakefulness. For both tasks, response speed and number of lapses (RTs > 500) per minute significantly increased with increasing hours of wakefulness. Overall, standardized response speed scores on the 5-min PDA-PVT closely tracked those of the PVT-192; however, the PDA-PVT was generally associated with more lapses/minute. Closer inspection of the data indicated that when the level of sleep loss and fatigue became more severe (i.e., Day 3), the 5-min PDA-PVT was not quite as sensitive as the 10-min PVT-192 when 2- to 10-sec foreperiods were used for both. It is likely, however, that the observed differences between the two devices was due to differences in task length. Thus, the findings provide further evidence of the validity of the 5-min PDA-PVT as a substitute for the 10-min PVT-192, particularly in circumstances in which a shorter test is required and/or the PVT-192 is not as practical.     

Reliability of the 5-min psychomotor vigilance task in a primary school classroom setting

This study evaluated the reliability of the 5-min psychomotor vigilance task (PVT) in a single-sex Australian primary school. Seventy-five male students (mean age 5 11.82 years, SD = 1.12) completed two 5-min PVTs using a Palm personal digital assistant (PDA) in (1) an isolated setting and (2) a classroom setting. Of this group of students, a subsample of 37 students completed a test-retest reliability trial within the classroom setting. Using a mixed-model analysis, there was no significant difference in the mean response time (RT) or number of lapses (RTs ≥ 500 msec) between the isolated and the classroom setting. There was, however, an order effect for the number of lapses in the isolated setting, with the number of lapses being greater if the isolated test was conducted second. Test-retest intraclass correlation coefficients (ICCs) in the classroom setting indicated moderate to high reliability (mean RT = .84, lapses = .59). Bland-Altman analysis showed no systematic difference between the two settings. Findings suggest that the 5-min PDA PVT is a reliable measure of sustained attention in the classroom setting in this sample of primary-aged schoolchildren. The results provide further evidence for the versatility of this measuring device for larger interventions outside the laboratory.     

Cardiac-somatic coupling during the foreperiod in a simple reaction-time task

The cardiac-somatic coupling hypothesis predicts a phasic decrease of general somatic behavior concomitant with a phasic heart-rate deceleration. This hypothesis was investigated during a constant 4 s foreperiod (FP) in a simple auditory reaction-time task. Intertrial interval duration was variable (mean 15.5 s; range 11–20 s). The response was a plantar flexion of the right foot. Besides ECG and EOG, surface EMG of nine striate muscles varying in relevance to response execution was recorded.In agreement with the hypothesis, heart rate, eye movements, and m. mylohyoideus EMG were decreased at the end of the FP. An increase in the EMG of the agonist m. soleus, antagonist m. tibialis anterior, m. peroneus longus, and m. trapezius was found during the FP. The activity in all other response-irrelevant muscles did not significantly differ from baseline. It was concluded that the results are at variance with the cardiac-somatic coupling hypothesis. Changes in surface EMG are discussed in terms of motor preparation.     

Workload and stress in vigilance: the impact of display format and task type

Signal salience was manipulated using configural and object displays to examine their effects on the performance, workload, and stress of vigilance. Improving performance and reducing the workload and stress of vigilance are crucial concerns. Signal salience improves performance and reduces stress, but to date there have been no salience manipulations using configural displays in a vigilance task. Two task types (individual variable monitoring and midpoint identification) and 3 display formats (bar graph-different baselines, bar graph-common baseline, and a polygon graph display) were examined. Configural displays improved performance in the midpoint identification task but not in the individual variable monitoring task. Workload depended on the form of display features (bar graph vs. polygon). Stress increased across all conditions, but task and display format did not affect stress. The midpoint identification task was associated with more emotion-focused and avoidant coping. Increasing signal salience in a vigilance task using configural displays with emergent features or physical contours can improve performance and reduce the decrement. These displays may not reduce the stress of vigilance or encourage task-focused coping. Therefore, there may be hidden costs to vigilance performance even when highly salient configural displays are used.     

Self-regulation of stimulation for ADD-H children during reading and vigilance task performance

The present study examines the hypothesis that motor responses added into rote tasks would modulate the sensation-seeking activity and impulsive errors of hyperactive (ADD-H) children. To this purpose 22 ADD-H and 25 comparison children were administered two repetitive tasks (word decoding and an auditory vigilance task) under both an active response and a passive response condition. Findings were that the impulsive errors, talking/noise-making, and activity of ADD-H children was normalized (i.e., did not differ from comparison children) only in the high stimulation active response conditions. Behavioral improvements for ADD-H children were documented in both tasks in the active condition, but performance gains were found only in the vigilance task. The findings supported predictions derived from the optimal stimulation theory that the excessive activity and attraction to novel stimuli of ADD-H children can be channeled into appropriate instrumental motor and attention responses.We thank Anne Dwyer for her help with data collection, and Phyllis Kikendall, Sylvia Kottler, Joe Boggs, and Cheryl Wieczorek for their assistance at various stages of this project. We are also most grateful to Martha Eger and to the teachers, Sally Schnieder and Denise Oliver, of West Central Joint Special Services, to Pat Welch of the Catholic Social Services, and to the teachers of St. Ann's School and St. Philip Neri School for their cooperation with this research.     

Deformation of the useful visual field with state of vigilance,task priority,and central task complexity

In a dual-task situation, peripheral perception can deteriorate due to different variables related to the experimental situation, such as central task complexity and the relative priority given to the two tasks. Recent studies have also shown that individual characteristics (such as the state of vigilance) can alter the useful visual field. The ability to perceive signals presented at different places in the visual field decreases in situations that lead to episodes of low vigilance. In Exp. 1, 27 subjects (18-29 years) had to perform a monotonous and prolonged dual-monitoring task involving central and peripheral vision. The test was carried out with two different sets of instructions regarding priority: the more important task was either the central task or the peripheral one. In Exp. 2, 18 subjects (18-30 years) performed the same test, but this time with two levels of complexity of the central task, either a simple monitoring activity or the same monitoring task coupled with a counting activity. Elliptical interpolation of the data enabled assessment of the deformation of the useful visual field in both experiments. The analysis of the parameters of the elliptical model indicated that the useful visual field mainly shrinks on the vertical axis, as the individual becomes drowsy. The useful visual field also shrinks on the horizontal axis when the peripheral task has priority and the monitoring activity is prolonged, or when the central task is complex.     

Inhibition of response mode in task switching

Task inhibition was explored in two experiments that employed a paradigm in which participants switched among three tasks. Two tasks required manual choice responses based on numerical judgment (parity or magnitude), whereas a third task required an unconditional double-press of both response keys. Both experiments showed that switching to a just-abandoned task (n-2 task repetition) generally leads to a performance cost relative to switching to another task. Specifically, this task inhibition effect also occurred for the double-press task, suggesting inhibition of response mode. Prolonging the task-cuing interval showed that advance task preparation reduced only inhibition of the double-press task but not of the choice tasks (Experiment 1). Prolonging the response-cue interval led to a decrease of the inhibition effect in all tasks (Experiment 2), suggesting a time-based release of task inhibition. Together, the experiments support the notion of a response-related component of task inhibition.     

Effect of mode of presentation on performance in a familiar task

Contrasting interpretations of the role of overt, exploratory activity in problem solving was evaluated by presenting a task that could be solved by the application of a familiar physical principle under abstract and concrete conditions. Contrary to what is found under unfamiliar task conditions, superior problem solving performance was obtained under the abstract condition. The findings support the hypothesis that the utility of overt, exploratory activity is related to the degree of novelty of the task.     

PC-PVT: A platform for psychomotor vigilance task testing,analysis, and prediction

Using a personal computer (PC) for simple visual reaction time testing is advantageous because of the relatively low hardware cost, user familiarity, and the relative ease of software development for specific neurobehavioral testing protocols. However, general-purpose computers are not designed with the millisecond-level accuracy of operation required for such applications. Software that does not control for the various sources of delay may return reaction time values that are substantially different from the true reaction times. We have developed and characterized a freely available system for PC-based simple visual reaction time testing that is analogous to the widely used psychomotor vigilance task (PVT). In addition, we have integrated individualized prediction algorithms for near-real-time neurobehavioral performance prediction. We characterized the precision and accuracy with which the system as a whole measures reaction times on a wide range of computer hardware configurations, comparing its performance with that of the “gold standard” PVT-192 device. We showed that the system is capable of measuring reaction times with an average delay of less than 10 ms, a margin of error that is comparable to that of the gold standard. The most critical aspect of hardware selection is the type of mouse used for response detection, with gaming mice showing a significant advantage over standard ones. The software is free to download from http://bhsai.org/downloads/pc-pvt/.