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10.1002/hup.769

Human psychopharmacology

Hum Psychopharmacol

A high sugar content, low caffeine drink does not alleviate sleepiness but may worsen it.

Although the ingestion of high levels of glucose might have a short acting alerting effect, there is evidence of an ensuing enhancement of sleepiness in people already sleepy. Some 'energy drinks' contain large quantity of sugars. We compared 250 ml of a well known 'energy drink' (42 g sugars, containing a low [30 mg] level of caffeine for 'flavouring') with a nil sugar nil caffeine, similar tasting control. These were given a week apart, in a repeated measures, double blind, balanced design, to 10 participants sleep restricted to 5 h the prior night. They had a light lunch, consumed a drink at 13:50 h, and 10 min later underwent 3 x 30 min consecutive periods at a reaction time (RT) task (the Psychomotor Vigilance Test), separated by 3 min breaks when self-ratings of sleepiness were made. The energy drink did not counteract sleepiness, and led to slower RTs and more lapses during the final 30 min session, around 80 min after consumption.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.apergo.2006.03.006

Applied ergonomics

Appl Ergon

Simulated train driving: fatigue, self-awareness and cognitive disengagement.

Fatigue is a serious issue for the rail industry, increasing inefficiency and accident risk. The performance of 20 train drivers in a rail simulator was investigated at low, moderate and high fatigue levels. Psychomotor vigilance (PVT), self-rated performance and subjective alertness were also assessed. Alertness, PVT reaction times, extreme speed violations (>25% above the limit) and penalty brake applications increased with increasing fatigue level. In contrast, fuel use, draft (stretch) forces and braking errors were highest at moderate fatigue levels. Thus, at high fatigue levels, errors involving a failure to act (errors of omission) increased, whereas incorrect responses (errors of commission) decreased. The differential effect of fatigue on error types can be explained through a cognitive disengagement with the virtual train at high fatigue levels. Interaction with the train reduced dramatically, and accident risk increased. Awareness of fatigue-related performance changes was moderate at best. These findings are of operational concern.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1440-1819.2006.01511.x

Psychiatry and clinical neurosciences

Psychiatry Clin Neurosci

Brief posturographic test as an indicator of fatigue.

The purpose of the present paper was to analyze the efficiency of an abbreviated, albeit objective posturographic test as an indicator of fatigue. Posturography was measured in 10 healthy adults (age 18-33 years, male/female 7/3). Baseline posturographic measurements were taken for each subject. Later, a shorter (3-min) posturographic test was administered 12 times during 25 h of sleep deprivation. This was correlated with subjective assessment of fatigue using a questionnaire and cognitive performance assessed with a reaction time test (Psychomotor Vigilance Test). Although showing significant individual differences, the score of the abbreviated posturographic examination, normalized to each subject's baseline performance ('fatigue index') had a pronounced circadian pattern with a peak of instability in the early morning hours. Fatigue index was highly correlated with the cognitive test (r=0.80-0.90). A substantial, albeit weaker correlation was found between the fatigue index and the subjective fatigue scores (r=0.59-0.75). Fourier spectral analysis showed that low median sway (0.10-0.50 Hz), considered to be an expression of vestibular control, was most affected by fatigue. The study demonstrates that cognitive deterioration caused by fatigue can be objectively predicted by an abbreviated postural test of <or=3 min. This test is promising to be valid, reliable, and practicable, while being significantly correlated with physiological markers and validated cognitive measures of fatigue obtained by substantially more time-consuming and less convenient methods.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.clinph.2006.03.011

Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology

Clin Neurophysiol

Validation of the Karolinska sleepiness scale against performance and EEG variables.

The Karolinska sleepiness scale (KSS) is frequently used for evaluating subjective sleepiness. The main aim of the present study was to investigate the validity and reliability of the KSS with electroencephalographic, behavioral and other subjective indicators of sleepiness. Participants were 16 healthy females aged 33-43 (38.1+/-2.68) years. The experiment involved 8 measurement sessions per day for 3 consecutive days. Each session contained the psychomotor vigilance task (PVT), the Karolinska drowsiness test (KDT-EEG alpha & theta power), the alpha attenuation test (AAT-alpha power ratio open/closed eyes) and the KSS. Median reaction time, number of lapses, alpha and theta power density and the alpha attenuation coefficients (AAC) showed highly significant increase with increasing KSS. The same variables were also significantly correlated with KSS, with a mean value for lapses (r=0.56). The KSS was closely related to EEG and behavioral variables, indicating a high validity in measuring sleepiness. KSS ratings may be a useful proxy for EEG or behavioral indicators of sleepiness.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/29.4.573

Sleep

Sleep

Sleepiness enhances distraction during a monotonous task.

Although sleepiness appears to heighten distraction from the task at hand, especially if the latter is dull and monotonous, this aspect of sleep loss has not been assessed in any systematic way. Distractions are a potential cause of performance lapses (as are micro-sleeps). Here, we investigate the effects of sleepiness on a monotonous task, with and without distraction. Repeated Measures 2 x 2 counterbalanced design, comprising Sleepiness (night sleep restricted to 5 hours x normal sleep) and Distraction (distraction x no distraction). Participants underwent 30-minute sessions on the Psychomotor Vigilance Test (2:00 PM - 3:10 PM), with or without an attractive distraction to be ignored, under normal and sleep-restricted conditions. Sixteen healthy young adults (mean age 21.10 years; 21-25 years [8 men; 8 women]) without any sleep or medical problems and without any indication of daytime sleepiness. Normal sleep versus sleep restricted to 5 hours and distraction versus no distraction. Distraction comprised a television in the visual periphery, showing an attractive video that had to be ignored. Psychomotor Vigilance Test performance was monitored, as were the participants' head turns toward the television via videocameras. There was a significant increase in both head turns and lapses during sleep restriction plus distraction. Moreover, sleepiness also increased head turns even during no distraction. Distracting effects of sleepiness were clearly evident during the initial 10 minutes of testing. Distractibility is an important aspect of sleepiness, which has relevance to safety in the real world, eg, sleepy driving.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/29.4.545

Sleep

Sleep

Effects of short-term CPAP withdrawal on neurobehavioral performance in patients with obstructive sleep apnea.

Changes in sleep parameters and neurobehavioral functioning were systematically investigated after an acute (1 night) and short-term (7 nights) period of withdrawal from continuous positive airway pressure (CPAP) treatment and 1 subsequent night of CPAP reintroduction in patients with obstructive sleep apnea. Repeated-measurement within-subject design. Sleep laboratory, university teaching hospital. Twenty participants receiving optimal CPAP therapy for > or = 12 months. CPAP withdrawal. Polysomnograms were performed on Night 0 (with CPAP), Night 1 and Night 7 (without CPAP) and Night 8_R (with CPAP). Acute CPAP withdrawal resulted in the recurrence of sleep-disordered breathing with sleep disruption, hypoxemia, and increased subjective sleepiness. Short-term CPAP withdrawal exacerbated hypoxemia, increased subjective and objective sleepiness and poor mood ratings. Neurobehavioral functioning assessed using the Psychomotor Vigilance Task was impaired following Night 7 and associated with hypoxemia and changes in morning levels of tumor necrosis factor-alpha. However, other neurobehavioral measures were not affected. Autonomic arousals measured via respiratory-related reductions in finger blood volume by peripheral arterial tonometry decreased from Night 1 to Night 7. On Night 8_R, reintroduction of CPAP treatment eliminated most airway obstruction, maintained oxygenation, and reversed daytime sleepiness and some vigilance decrements. Despite recurrence of sleep-disordered breathing with increased sleepiness and impaired vigilance, most neurobehavioral variables were unaffected by CPAP withdrawal. The reduction in vigilance appeared to be associated with worsened hypoxemia and changed levels of tumor necrosis factor-alpha. Resumption of CPAP treatment had immediate benefits on sleep consolidation and subjective sleepiness.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/29.4.462

Sleep

Sleep

Indoor exposure to natural bright light prevents afternoon sleepiness.

The present study examined the effects of indoor exposure to natural bright light on afternoon sleepiness. Participants took part in 3 experimental conditions: (1) a natural bright light condition in which they carried out performance and arousal tests sitting near a window (3260.0 +/- 1812.43 lux) from 12:40 PM to 1:10 PM, (2) a nap condition in which they were provided a nap opportunity for 20 minutes from 12:45 PM, and (3) a control condition in which they performed the tests in less than 100 lux surroundings from 12:40 PM to 1:10 PM. Before and after each treatment, the same series of tests were administered. A temperature- and light-controlled sleep laboratory. Sixteen healthy female paid volunteers aged 33 to 43 (38.1 +/- 2.68) years. Indoor natural bright light and a short nap. Arousal levels were measured by the Psychomotor Vigilance Task, Alpha Attenuation Test, Karolinska Drowsiness Test, and Karolinska Sleepiness Scale. The tests were repeated every 30 minutes from 11:00 AM to 4:10 PM. Ambient light intensity was maintained at less than 100 lux, except during natural bright light exposure. Short-term exposure to natural bright light significantly improved afternoon arousal levels, as measured by the Karolinska Drowsiness Test and Alpha Attenuation Test, the effects of which continued for at least 60 minutes (1:10-2:10 PM). However, no significant differences were observed between conditions for Psychomotor Vigilance Test performance. Brief indoor exposure to natural bright light may decrease afternoon sleepiness. This technique of light could be used in work settings in which napping is not permitted.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Sleep

Sleep

Tiagabine is associated with sustained attention during sleep restriction: evidence for the value of slow-wave sleep enhancement?

To evaluate the impact of enhanced slow-wave sleep (SWS) on behavioral, psychological, and physiologic changes resulting from sleep restriction A double-blind, parallel-group, placebo-controlled design was used to compare tiagabine, 8 mg, (a SWS-enhancing drug) to placebo during 4 nights of sleep restriction (time in bed = 5 hours per night). Behavioral, psychological, and physiologic measures of the impact of sleep restriction were compared between groups at baseline, during sleep restriction, and following recovery sleep. Two sleep research laboratories. Thirty-eight healthy adults; 9 men and 10 women (mean age: 26.0 +/- 6.1 years) in the placebo group and 8 men and 11 women (mean age: 26.7 +/- 8.1 years) in the tiagabine 8 mg group Both experimental groups underwent 4 nights of sleep restriction. Each group received either tiagabine 8 mg or placebo on all sleep-restriction nights, and both groups received placebo on baseline and recovery nights. Polysomnography documented a SWS-enhancing effect of tiagabine. The placebo group displayed the predicted deficits due to sleep restriction on the Psychomotor Vigilance Task and the Multiple Sleep Latency Test. Compared with placebo, the tiagabine group did not demonstrate impairment in sustained attention on the Psychomotor Vigilance Test, performed better on the Wisconsin Card Sorting Task, reported more restorative sleep, and had less of an increase in afternoon-evening salivary free cortisol. Multiple Sleep Latency Test, ratings of sleepiness, recovery sleep, and other measures did not differ between groups. To our knowledge these findings are the first to be consistent with the hypothesis that pharmacologic SWS enhancement reduces selective aspects of the behavioral, psychological, and physiologic impact of sleep restriction.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/03610730600553968

Experimental aging research

Exp Aging Res

Interaction of age with shift-related sleep-wakefulness, sleepiness, performance, and social life.

It is not clear how the age-related changes in sleep are related to performance and subjective sleepiness at different time of the day. The aim of the present study was to study work shift related interactions of age with sleep-wakefulness, performance, and social life. A representative sample of aircraft maintenance workers in a continuous three-shift system was studied by a questionnaire (n = 275) and an on-site field (n = 49) study. In the field study, sleep length and quality and different ratings of social and other activities were studied with an actigraphy and a Pocket PC diary during 15 consecutive days. Subjective sleepiness (KSS) and vigilance performance (PVT) were registered at work. Although the shift type influenced the sleep, subjective sleepiness, performance, and social life, age was distinctly related only to shift-related changes in the amount of sleep, subjective sleepiness, and psychomotor vigilance. Night shifts were related with shorter sleep, decreased performance, and increased sleepiness. Although subjective sleepiness was greatest among the youngest (25-34 years) age group during the morning and the night shifts, the increase of performance lapses was higher among the middle-aged (35-49 years) and senior (50-58 years) groups during the night shifts compared to the youngest age group. According to the questionnaire, older shiftworkers also tended to perceive more frequently that subjective sleepiness decreases their work performance during the morning and night shifts. The results indicate of no direct link between age-related differences in subjective sleepiness and performance at night work. The shorter day sleep after the night shifts and higher deterioration of subjective and objective performance according to age urge on development of shift schedules aiming at lower fatigue levels during the night shifts.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2006.00495.x

Journal of sleep research

J Sleep Res

Chronic partial sleep loss increases the facilitatory role of a masked prime in a word recognition task.

Neurobehavioural performance deficits associated with sleep loss have been extensively studied, in particular, the effects on psychomotor performance. However, there is no consensus as to which, if any, cognitive functions are impaired by sleep loss. To examine how sleep loss might affect cognition, the automatic processes supporting word recognition were examined using the masked priming paradigm in participants who had been exposed to two consecutive days of sleep restriction. Twelve healthy volunteers (mean age 24.5 years) were recruited. Nocturnal sleep duration was restricted to 60% of each participant's habitual sleep duration for two consecutive nights by delaying scheduled time of sleep onset and advancing time of awakening. In controlled laboratory conditions, participants completed the Psychomotor Vigilance Task and Karolinska Sleepiness Scale and a masked priming word recognition task. As expected, significant increases in subjective sleepiness and impaired psychomotor performance were observed after sleep loss. In contrast, response times and error rate on the masked priming task were not significantly affected. However, the magnitude of the masked priming effect, which can be taken as an index of automaticity of lexical processing, increased following sleep loss. These findings suggest that while no evidence of impairment to lexical access was observed after sleep loss, an increase in automatic processing may occur as a consequence of compensatory mechanisms.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Sleep

Sleep

Sleep deprivation in rats produces attentional impairments on a 5-choice serial reaction time task.

To develop a rodent model of the attentional dysfunction caused by sleep loss. The attentional performance of rats was assessed after 4, 7, and 10 hours of total sleep deprivation on a 5-choice serial reaction time task, in which rats detect and respond to brief visual stimuli. The rats were housed, sleep deprived, and behaviorally tested in a controlled laboratory setting. Ten male Long-Evans rats were used in the study. Rats were trained to criteria and subsequently tested in daily sessions of 100 trials at approximately 4:00 PM (lights on 8:00 AM-8:00 PM). Attentional performance was measured after 4, 7, 10 hours of total sleep deprivation induced by gentle handling. Sleep deprivation produced a monotonic increase in response latencies across the 4-hour, 7-hour, and 10-hour deprivations. Sleep deprivation also led to increased omission errors, but the overall number of perseverative and premature responses was unchanged. Subgroups of rats were differentially affected in the number of omission errors and perseverative responses. The effects of sleep deprivation on rats are compatible with a range of human findings on the effects of sleepiness on selective attention, psychomotor vigilance, and behavioral control. Rats also exhibited differential susceptibility to the effects of sleep deprivation, consistent with 'trait-like' susceptibility that has been found in humans. These findings indicate the feasibility of using the 5-choice serial reaction time task as an animal model for investigating the direct links between homeostatic sleep mechanisms and resulting attentional impairments within a single animal subject.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/29.1.55

Sleep

Sleep

Age-related changes in the time course of vigilant attention during 40 hours without sleep in men.

To examine whether vigilant attention and sleepiness develop differently during prolonged wakefulness in young and older men. Psychomotor vigilance task (PVT) performance and subjective sleepiness were determined in 14 sessions at 3 hour intervals in healthy young (n = 12, mean age: 25.2 years, range: 21-31 years) and older (n = 11, mean age: 66.4 years, range: 61-70 years) men who were kept awake for 40 hours under continuous supervision in a sleep laboratory and on the morning after the recovery night. PVT speed, response lapses and performance variability, and subjective sleepiness were analyzed. Sleep deprivation led to reversal of an age-related difference in PVT speed at the circadian trough of performance on the morning of the second day of prolonged wakefulness (Session x Age interaction: P < .0006). Beginning after 22 hours of wakefulness, the young men also produced more lapses (P < .004), showed higher performance instability (P < .0001), and felt sleepier (P < .03) than older men, especially during the morning after the night without sleep. Vigilant attention is more impaired after 1 night without sleep in young men than in older men, which has important implications for the prevention of accidents associated with the loss of sleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/29.1.39

Sleep

Sleep

Laboratory and field studies of naps and caffeine as practical countermeasures for sleep-wake problems associated with night work.

To evaluate the effects of napping, caffeine, and napping plus caffeine on performance and alertness in both laboratory and field settings. (1) Laboratory Study: parallel-groups design with random assignment to 1 of 4 experimental conditions. (2) Field Study: crossover design. Sleep laboratory and field settings. (1) Laboratory Study: 68 healthy individuals; (2) Field Study: 53 shiftworkers who worked nights or rotating shifts. (1) Laboratory Study: an evening nap opportunity before the first 2 of 4 consecutive simulated night shifts plus placebo taken all 4 nights, caffeine taken nightly, the combination of the nap and caffeine conditions, or placebo. (2) Field Study: an evening nap on the first 2 of 4 consecutive night shifts plus caffeine taken nightly versus placebo taken nightly without naps. (1) Laboratory Study: Napping, caffeine, and their combination all improved alertness and performance as measured by Maintenance of Wakefulness Test and Psychomotor Vigilance Task, but the combination of napping and caffeine was best in improving alertness. (2) Field Study: Napping plus caffeine improved performance as measured by Psychomotor Vigilance Test and decreased subjective sleepiness in individuals working the night shift. Napping plus caffeine helps improve performance and alertness of night-shift workers.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Dialogues in clinical neuroscience

Dialogues Clin Neurosci

Hypersomnia.

Hypersomnia, a complaint of excessive daytime sleep or sleepiness, affects 4% to 6% of the population, with an impact on the everyday life of the patient Methodological tools to explore sleep and wakefulness (interview, questionnaires, sleep diary, polysomnography, Multiple Sleep Latency Test, Maintenance of Wakefulness Test) and psychomotor tests (for example, psychomotor vigilance task and Oxford Sleep Resistance or Osler Test) help distinguish between the causes of hypersomnia. In this article, the causes of hypersomnia are detailed following the conventional classification of hypersomnic syndromes: narcolepsy, idiopathic hypersomnia, recurrent hypersomnia, insufficient sleep syndrome, medication- and toxin-dependent sleepiness, hypersomnia associated with psychiatric disorders, hypersomnia associated with neurological disorders, posttraumatic hypersomnia, infection (with a special emphasis on the differences between bacterial and viral diseases compared with parasitic diseases, such as sleeping sickness) and hypersomnia, hypersomnia associated with metabolic or endocrine diseases, breathing-related sleep disorders and sleep apnea syndromes, and periodic limb movements in sleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1185/030079906X80378

Current medical research and opinion

Curr Med Res Opin

Pharmacodynamic effects on alertness of single doses of armodafinil in healthy subjects during a nocturnal period of acute sleep loss.

To assess the pharmacodynamics of armodafinil compared with modafinil and placebo on measures of alertness in healthy volunteers undergoing sleep loss. In a double-blind, active- and placebo-controlled, parallel-group study, 107 healthy male volunteers (aged 18-40 years) were randomized to receive a single oral dose of armodafinil (100, 150, 200, or 300 mg), modafinil (200 mg), or placebo administered at 19:25 h. The primary outcome was the Maintenance of Wakefulness Test (MWT), administered every 2 hours from 22:00-08:00 h. Secondary outcomes included the Psychomotor Vigilance Task (PVT) and the Karolinska Sleepiness Scale. Blood samples for pharmacokinetic analysis were collected hourly. Adverse events were evaluated throughout the 2-day laboratory stay and by telephone on day 9. All four doses of armodafinil, and the dose of 200 mg modafinil, improved wakefulness as measured by increased MWT latencies (treatment effect, p < 0.0001) and reduced PVT lapses of attention (treatment effect, p < 0.0001). The magnitude and duration of these effects at the later time points appeared to be dose and concentration dependent. Armodafinil at 200 mg resulted in comparable C(max), a later t(max), and higher plasma concentrations 6-14 hours post-drug administration than with 200 mg modafinil. Following armodafinil, longer MWT latencies and fewer PVT lapses 6 to approximately 14 hours post-drug administration were observed compared with modafinil. Armodafinil doses were well tolerated, with the most common adverse events including abdominal pain, nausea, and headache. There were reports of tachycardia/palpitations. Decreased mean sleep efficiency and increased mean blood pressure were also observed. Armodafinil improved alertness at all doses studied. Relative to modafinil 200 mg, armodafinil 200 mg showed a comparable peak plasma concentration with higher concentrations 6-14 hours post-drug, and improved wakefulness and sustained attention for a longer time post-dose. Both drugs were well tolerated; however, further research on the efficacy, safety, and tolerability of armodafinil in patients with disorders of excessive sleepiness (ES) is required.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.bbr.2005.11.018

Behavioural brain research

Behav Brain Res

Gender and age differences in psychomotor vigilance performance under differential sleep pressure conditions.

The effects of sleep pressure and circadian phase on neurobehavioral function can be sensitively measured with the psychomotor vigilance task (PVT). We compared PVT performance in 16 young (8 men and 8 women, 20-31 years) and 16 elderly healthy subjects (8 men and 8 women, 57-74 years) during a 40-h sleep deprivation (SD, high sleep pressure) and a 40-h multiple nap protocol (NAP, low sleep pressure) under dim light and constant posture conditions in a balanced crossover design. Independent of age and sleep pressure conditions, women exhibited significantly slower reaction times (RTs) than men. This effect became more apparent with increasing time elapsed into both the 40-h NAP and SD protocol. However, women tended to have fewer premature key presses than men. Independent of gender, the elderly showed slower RTs than the young in the NAP protocol during the biological day (8-24 h) but not during the biological night (24-8 h). In the SD protocol, they had also significantly slower RTs but only during the first 16 h under low to moderate levels of sleep pressure conditions. The relative PVT performance decline after SD was significantly less pronounced in the elderly than in the young, so that both age groups exhibited similar performance decrements after 16 h into the SD protocol. Thus, nighttime- and sleep pressure-related RT slowing in the young "makes them old", or the elderly are less susceptible to circadian and wake-dependent PVT performance decrements. We interpret the gender effect as a different strategy in women when performing the PVT, although the instructions to be 'as fast as possible' were identical. Not only sleepiness and circadian phase, but also age and gender are major factors that may contribute to attentional failures in extended work shifts and during nighttime work shifts.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/28.11.1386

Sleep

Sleep

Sleep and motor performance in on-call internal medicine residents.

To compare vigilance and performance among internal medicine residents doing in-house call versus residents not doing in-house call. Prospective study of resident cohorts with repeated testing. University Teaching Hospital. Internal medicine residents doing in-house call and residents not doing in-house call (pathology, endocrinology) (controls). Subjective sleepiness scores (daily Stanford Sleepiness Scale and Epworth Sleepiness Scale at start and end of the test period), actigraphy, and daily sleep logs as well as regular psychomotor vigilance testing using a Palm version (Walter Reed Army Institute of Research) of the Psychomotor Vigilance Test (PVT). Subjects were enrolled for a period of 28 to 32 days, which included 4 to 6 on-call nights for the internal medicine residents. Controls took call from home. Participants were compensated for their time. Twenty residents were evaluated, 13 internal medicine and 7 controls. Overall median reaction time was slower in the internal medicine residents (264.7 +/- 102.9 vs 239.2 +/- 26.1 milliseconds; P < .001). Internal medicine residents showed no difference in reaction time postcall versus other periods (269.9 +/- 131.2 vs 263.6 +/- 95.6; P = .65). Actigraphic sleep time was shorter during on-call than noncall nights and in internal medicine residents as compared with controls (287.48 +/- 143.8 vs 453.49 +/- 178.5 and 476.08 +/- 71.9 minutes; P < .001). Internal medicine residents had significantly greater major and minor reaction-time lapses compared with controls (1.26 +/- 3.4 vs 0.53 +/- 1.1 & 2.4 +/- 7.4 vs 0.45 +/- 1.0; P < .001). They reported increased sleepiness on postcall days compared with the start of their call (Stanford Sleepiness Scale: 3.26 +/- 1.2 vs 2.22 +/- 0.8; P < .001) but had scores similar to those of controls by their next call (2.22 +/- 0.8 vs 2.07 +/- 0.8; P = .13). Internal medicine residents have impaired reaction time and reduced vigilance compared with controls. Despite subjective improvements in sleepiness postcall, there was no change in their objective performance across the study period, suggesting no recovery. Internal medicine residents did not get extra sleep on postcall nights in an attempt to recover their lost sleep time. Implications for residents' well-being and patient care remain unclear.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Multiple caffeine doses maintain vigilance during early morning operations.

When used to counteract the effects of sleep deprivation, multiple doses of caffeine are typically ingested across an extended period of time. The goal of this study was to determine the optimal dose of caffeine for sustaining performance during sleep loss with administration of multiple doses. There were 48 subjects (28 men, 20 women) who were randomly assigned to 1 of 4 groups (placebo, 50, 100, or 200 mg caffeine). After an overnight 8-h sleep period, subjects were required to remain awake for the ensuing 29 h. Control data were collected until 03:00 (Day 3), followed by three 2-h test blocks. At 03:00, 05:00, and 07:00 subjects chewed two sticks of gum (Stay Alerts chewing gum) containing caffeine or placebo. Six 10-min sessions on a version of the Psychomotor Vigilance Test (PVT) were completed during each 2-h test block. The Stanford Sleepiness Scale (SSS) was administered after each PVT. Lapses on the PVT were categorized as response times greater than 1, 3, or 5 s. Lapses in all categories significantly increased in the placebo group. Caffeine significantly reduced the number of lapses in a dose-related manner; and performance was maintained at baseline levels for the entire sleep loss period with multiple doses of 200 mg caffeine. There was a significant main effect for session on the SSS, the score increasing over time, but no significant differences between groups. These results indicate that a bi-hourly administration of 200 mg of caffeine maintains vigilance performance across a single night without sleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/28.10.1283

Sleep

Sleep

Age modulates the effects of sleep restriction in women.

To investigate how age influences the effects of 3 nights of sleep restriction in healthy women. After a baseline night, sleep was restricted to 4 hours during 3 consecutive nights. One recovery night followed the sleep restriction. The sleep-restriction experiments were conducted under standardized conditions with continuous electroencephalographic ambulatory recordings. Before entering the study, the subjects underwent a polysomnographic recording for exclusion of sleep disorder and adaptation to the laboratory environment. Eleven young women (aged 20-30 years) and 10 older women (aged 55-65 years) were included in the study. The subjects were admitted to the sleep laboratory for 5 consecutive nights and days. After 1 baseline night, 3 nights of sleep restriction to 4 hours were performed and were followed by 1 recovery night of 8 hours. Continuous ambulatory electroencephalographic recordings were performed, as well as the Maintenance of Wakefulness Test (8:30 AM and 1:30 PM), the Stanford Sleepiness Scale, and the Psychomotor Vigilance Test. Young women were more affected by sleep restriction than were the older women. This was evidenced by more sleep onsets during the Maintenance of Wakefulness Test sessions in the young subjects, who also rated themselves more sleepy than the older women. Age influences the impact of sleep restriction on vigilance in women.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Sleep

Sleep

The neural basis of the psychomotor vigilance task.

To identify brain regions underlying the fastest and slowest reaction times on the Psychomotor Vigilance task (PVT) under well-rested conditions, as well as brain regions related to particularly poor performance after sleep deprivation. Subjects took the PVT twice while undergoing functional magnetic resonance imaging: once 12 hours after waking from a normal night of sleep and once after 36 hours of total sleep deprivation (TSD). Session order was counterbalanced. UCSD J. Christian Gillin Laboratory for Sleep and Chronobiology (the sleep core of the General Clinical Research Center) and UCSD Magnetic Resonance Institute. Twenty right-handed healthy adults (8 women; age = 27.4 +/- 6.7 years; education = 15.6 +/- 1.5 years). After a normal night of sleep, optimal performance was related to greater cerebral responses within a cortical sustained attention network and the cortical and subcortical motor systems. Slow reaction times, particularly after TSD, were associated with greater activity in the "default mode network" consisting of frontal and posterior midline regions. Optimal performance on the PVT appears to rely on activation both within the sustained attention system and within the motor system. Poor performance following TSD may result from a disengagement from the task and related inattention, and brain regions responsible for this localize within midline structures shown to be involved in the brain's "default mode." Finally, particularly poor performance after TSD may elicit a subsequent attentional recovery that manifests as greater activation within the same regions normally responsible for fast reaction times.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2005.00468.x

Journal of sleep research

J Sleep Res

Performance and alertness effects of caffeine, dextroamphetamine, and modafinil during sleep deprivation.

Stimulants may provide short-term performance and alertness enhancement during sleep loss. Caffeine 600 mg, d-amphetamine 20 mg, and modafinil 400 mg were compared during 85 h of total sleep deprivation to determine the extent to which the three agents restored performance on simple psychomotor tasks, objective alertness and tasks of executive functions. Forty-eight healthy young adults remained awake for 85 h. Performance and alertness tests were administered bi-hourly from 8:00 hours day 2 to 19:00 hours day 5. At 23:50 hours on day 4 (after 64 h awake), subjects ingested placebo, caffeine 600 mg, dextroamphetamine 20 mg, or modafinil 400 mg (n=12 per group). Performance and alertness testing continued, and probe tasks of executive function were administered intermittently until the recovery sleep period (20:00 hours day 5 to 8:00 hours day 5). Bi-hourly postrecovery sleep testing occurred from 10:00 hours to 16:00 hours day 6. All three agents improved psychomotor vigilance speed and objectively measured alertness relative to placebo. Drugs did not affect recovery sleep, and postrecovery sleep performance for all drug groups was at presleep deprivation levels. Effects on executive function tasks were mixed, with improvement on some tasks with caffeine and modafinil, and apparent decrements with dextroamphetamine on others. At the doses tested, caffeine, dextroamphetamine, and modafinil are equally effective for approximately 2-4 h in restoring simple psychomotor performance and objective alertness. The duration of these benefits vary in accordance with the different elimination rates of the drugs. Whether caffeine, dextroamphetamine, and modafinil differentially restore executive functions during sleep deprivation remains unclear.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3758/bf03206404

Behavior research methods

Behav Res Methods

The Walter Reed palm-held psychomotor vigilance test.

This field-portable reaction time test and analysis software run on devices using the Palm operating system. It is designed to emulate a test and commercial device widely used in sleep deprivation, shift work, fatigue, and stimulant drug research but provides additional capabilities. Experimental comparisons with the standard commercial device in a 40-hour total sleep deprivation study show it to be comparably sensitive to selected experimental variables. A Pocket PC-compatible version is under developement.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1056/NEJMoa041292

The New England journal of medicine

N Engl J Med

Modafinil for excessive sleepiness associated with shift-work sleep disorder.

Patients with shift-work sleep disorder chronically have excessive sleepiness during night work and insomnia when attempting to sleep during the day. We evaluated the use of modafinil for treating sleepiness in patients with this disorder. In a three-month, double-blind trial, we randomly assigned 209 patients with shift-work sleep disorder to receive either 200 mg of modafinil or placebo before the start of each shift. Assessments were performed with the use of the nighttime Multiple Sleep Latency Test, the Clinical Global Impression of Change, the Psychomotor Vigilance Test, diaries of patients, and daytime polysomnography. After randomization, we conducted monthly assessments. Treatment with modafinil, as compared with placebo, resulted in a modest improvement from baseline in mean (+/-SEM) nighttime sleep latency (the interval between the time a person attempts to fall asleep and the onset of sleep) (1.7+/-0.4 vs. 0.3+/-0.3 minutes, respectively; P=0.002), and more patients had improvement in their clinical symptoms (74 percent vs. 36 percent, respectively; P<0.001). Patients who were receiving modafinil also had a reduction in the frequency and duration of lapses of attention during nighttime testing of their performance on the Psychomotor Vigilance Test (change from baseline, a reduction in lapse frequency of 2.6 vs. an increase of 3.8, respectively; P<0.001), and proportionally fewer patients reported having had accidents or near accidents while commuting home (29 percent vs. 54 percent, respectively; P<0.001). Despite these benefits, patients treated with modafinil continued to have excessive sleepiness and impaired performance at night. Modafinil did not adversely affect daytime sleep as compared with placebo. Headache was the most common adverse event. Treatment with 200 mg of modafinil reduced the extreme sleepiness that we observed in patients with shift-work sleep disorder and resulted in a small but significant improvement in performance as compared with placebo. However, the residual sleepiness that was observed in the treated patients underscores the need for the development of interventions that are even more effective.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Visual perception, psychomotor performance, and complex motor performance during an overnight air refueling simulated flight.

Visual perception task, complex motor flight task, and psychomotor vigilance task performances were evaluated in U.S. Air Force pilots navigating a high-fidelity fixed wing jet simulator over 26.5 h of continuous wakefulness. Eight military pilots on flight status performed the primary task of flying a simulated 12.5-h overnight mission in an Air Refueling Part Task Trainer (ARPTT): Response omission to presentation of single- and double-light stimuli displayed in random sequence across the cockpit instrument panel was the metric used to assess choice visual perception task (CVPT) performance. Deviation from an established azimuth heading in the ARPTT during the CVPT was the flight metric used to assess complex motor performance. Speed, lapse, false start, and anticipation were the metrics used to assess psychomotor vigilance task (PVT) performance during crew rest periods. Significant visual perceptual, complex motor, and psychomotor vigilance (speed and lapse) impairments occurred at 19 h awake in the eight-subject group. CVPT response omissions significantly correlated with ARPTT azimuth deviations at r = 0.97, and with PVT speed at r = -0.92 and lapses at r = 0.90. ARPTT azimuth deviations significantly correlated with PVT speed at r = -0.92 and lapses at r = 0.91. Acute sleep deprivation degrades visual perceptual, complex motor, and simple motor performance. Complex motor impairments strongly correlate with visual perceptual impairments. This research provides support for the use of visual perceptual measures as surrogates of complex motor performance in operational situations where the primary cognitive inputs are through the visual system.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.csm.2004.12.007

Clinics in sports medicine

Clin Sports Med

Sleep, circadian rhythms, and psychomotor vigilance.

Psychomotor vigilance performance is highly relevant to athletic performance. It is influenced by a sleep homeostatic process, which builds up pressure for sleep during wakefulness and dissipates this pressure during sleep, and a circadian rhythm process, which produces a waxing and waning of pressure for wakefulness over a 24 hours of the day. During total sleep deprivation, these two processes cause performance to deteriorate progressively over days, modulated within days by further performance reductions at night and relative improvements during the daytime. As the homeostatic pressure for sleep builds up higher across prolonged wakefulness, the rate of dissipation of that pressure during subsequent sleep is enhanced exponentially, so that even brief periods of sleep provide significant performance recuperation. Nevertheless, sleep restriction practiced on a chronic basis induces cumulative performance deficits of the same order of magnitude as observed during total sleep deprivation. There are also considerable individual differences in the degree of vulnerability to performance impairment from sleep loss, and these differences represent a trait.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Fatigue assessment in the field: validation of a hand-held electronic psychomotor vigilance task.

In recent years, there has been an increasing need for a reliable and practical tool for assessing fatigue-related impairment in the field. This study investigated the sensitivity of one potential tool, a 5-min version of the psychomotor vigilance task (PVT) specifically designed for use on personal digital assistants (PDA), to 28 h of sustained wakefulness. There were 15 participants who slept in the laboratory overnight then remained awake from 08:00 (Day 1) to 12:00 (Day 2). During every second hour, they completed a 10-min PVT, a sustained attention task that is sensitive to the effects of sleep loss and fatigue, and a 5-min PDA-PVT. While performance on both tasks significantly varied as a function of hours of wakefulness, responses on the PDA-PVT were typically slower than on the PVT. When performance scores were standardized, the negative impact of increasing hours of wakefulness on performance on the 5-min PDA-PVT and 10-min PVT did not significantly differ. The findings suggest that the 5-min PDA-PVT may provide a reasonable substitute for the 10-min PVT, particularly in circumstances where a shorter test is required and/or the standard PVT is not as practical.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1136/thx.2004.032078

Thorax

Thorax

Randomised controlled crossover trial of humidified continuous positive airway pressure in mild obstructive sleep apnoea.

It is unclear whether continuous positive airway pressure (CPAP), the treatment of choice for severe obstructive sleep apnoea (OSA), is effective at improving outcomes in mild OSA. To help define the role of humidified CPAP in mild OSA, a randomised crossover study was undertaken of patients with an apnoea hypopnoea index (AHI) of 5-30/hour. Subjective sleepiness, objective wakefulness, mood, reaction time, and quality of life were measured at baseline, after 3 weeks treatment with humidified CPAP and 3 weeks sham CPAP (2 week washout). Twenty nine of 31 enrolled patients (age 25-67 years, seven women, mean (SD) body mass index 31.5 (6) kg/m2) completed the protocol. Humidified CPAP improved polysomnographic indices of OSA and Epworth Sleepiness Scale (2.4 points (95% CI 0.6 to 4.2)). Objective wakefulness (modified maintenance of wakefulness test) showed a trend towards improvement (5.2 minutes (95% CI -0.6 to 11)). Mood (Hospital Anxiety and Depression Scale), quality of life (SF 36, Functional Outcomes of Sleep Questionnaire), and reaction times (Psychomotor Vigilance Task) were not improved more than sham CPAP. Compliance with humidified and sham CPAP both averaged 4.9 hours/night. Placebo effects were evident in many outcomes and there was no clear treatment preference. Humidified CPAP improves subjective sleepiness and possibly objective wakefulness but not reaction times, quality of life, or mood. These results do not support the routine use of CPAP in all patients with mild OSA, but offers some support for the trialling of CPAP in those with severe sleepiness.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1164/rccm.200409-1244OC

American journal of respiratory and critical care medicine

Am J Respir Crit Care Med

The effect of infective exacerbations on sleep and neurobehavioral function in cystic fibrosis.

Adults with cystic fibrosis (CF) are susceptible to hypoxemia, hypercapnia, arousal from sleep, and neurobehavioral impairment. We hypothesized that pulmonary exacerbations would adversely affect sleep and neurobehavioral performance. Patients with exacerbations (cases) had sleep studies and neurobehavioral testing before and after inpatient intravenous therapy. Adults with stable CF underwent the same testing procedures (control subjects). When clinically stable, cases and control subjects had similar lung function, intelligence, and body mass index. Among cases, treatment of an exacerbation improved lung function, quality of life, mood, sleepiness, and activation. Cases spent more time awake after sleep onset (p = 0.02), less time in REM sleep (p = 0.03), and were more hypoxemic than control subjects when unwell. The severity of hypoxemia correlated with lung function. On admission, cases had slower throughput than control subjects in the serial addition and subtraction task (cases, 16 +/- 4, vs. control subjects, 17 +/- 3; F[1, 36] = 5.15, p = 0.03) and a slower response time on the digit symbol substitution task (F[1, 36] = 11.91, p = 0.001), which persisted after treatment (F[1, 36] = 8.48, p = 0.006). Cases experienced significant improvements in sleep efficiency, amount of REM sleep, and hypoxia with treatment. Their performance in the serial addition and subtraction task, psychomotor vigilance task, and simulated driving task also improved with treatment. Sex modified the effect of an exacerbation on some aspects of performance. Exacerbations of lung disease in adults with CF adversely affect sleep and tests of neurobehavioral performance regardless of underlying disease severity. The implications for performance in daily life need further evaluation because patients often delay admission to hospital to fulfill study or work commitments.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.otohns.2004.11.013

Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery

Otolaryngol Head Neck Surg

Multilevel temperature-controlled radiofrequency for obstructive sleep apnea: extended follow-up.

To determine long-term effectiveness of multilevel (tongue and palate) temperature-controlled radiofrequency tissue ablation (TCRFTA) for patients with obstructive sleep apnea syndrome (OSAS). Prospective, 2-institution case series. Twenty-nine subjects with mild to moderate OSAS and who were at least 1 year from completion of multilevel TCRFTA were included, representing a subset of subjects who were enrolled in a previously published controlled trial. Exclusion criteria for this extended follow-up study included any additional treatment for OSAS after completion of TCRFTA. Median follow-up was 23 months. Daytime sleepiness and OSAS-related quality of life were significantly improved at extended follow-up (both P < 0.001). Median reaction time testing and apnea-hypopnea index (AHI) were also significantly improved at long-term follow-up (P = 0.03 and 0.01). Body mass index was unchanged (P = 0.94). Multilevel TCRFTA treatment of mild to moderate OSAS resulted in prolonged improvement in daytime somnolence, OSAS-related quality of life, psychomotor vigilance, and AHI in this group of subjects at extended follow-up.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2005.00442.x

Journal of sleep research

J Sleep Res

Less effective executive functioning after one night's sleep deprivation.

The prefrontal cortex (PFC) is affected negatively by sleep deprivation (SD) and executive functioning is largely dependent on activity in the PFC. Earlier studies have focused on subsystems of executive functioning, and tests of executive functioning have shown both low reliability and low validity. In the present study, 11 healthy volunteers were sleep deprived and compared with 11 healthy controls in a study on effects of one night's SD on integrative executive functioning. Following SD, the performance of subjects on an ecologically valid test, the modified Six Elements Test, was significantly impaired. There were no group differences on psychomotor vigilance, verbal or visuo-spatial working memory. This extends previous knowledge of performance effects of SD, and may be of special importance for individuals with cognitive work tasks.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Caffeine effects on recovery sleep following 27 h total sleep deprivation.

Caffeine is widely used to reverse alertness and performance decrements. However, caffeine's effects on subsequent recovery sleep and post-recovery performance are not well documented and, therefore, were evaluated. Six habitually low (LC: < or = 100 mg x d(-1)) and three habitually high (HC: > or = 400 mg x d(-1)) caffeine users completed a randomized crossover design. After 20 h of wakefulness, repeated doses of caffeine gum [0 (placebo) mg, 100 (low dose) mg, or 300 (high dose) mg] were administered at 03:00, 05:00, and 07:00. At 10:00 (27 h sleep deprivation) subjects slept for 8 h, followed by Psychomotor Vigilance Task (PVT) administration at 33 and 65 min post-awakening. Low dose caffeine increased stage 1 minutes only. However, high dose caffeine impaired sleep maintenance (reduced total sleep time/increased wake) and reduced sleep depth (increased stage 1 minutes/percentage and slow-wave sleep (SWS) latency, and reduced SWS minutes during the first third of the sleep period). With high dose caffeine, LC users had less SWS percentage as compared with HC users. The HC users had reduced stage 2 percentage with high dose caffeine as compared with placebo and low dose caffeine. Caffeine dose and habitual caffeine use did not influence post-recovery sleep PVT performance. Caffeine exerts mild deleterious dose-response effects on recovery sleep following total sleep deprivation, primarily early in the sleep period, with potential recovery from these effects after sufficient sleep as suggested by lack of post-recovery sleep performance deficits. Habitual caffeine use appears to minimally reduce caffeine effects.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.2486/indhealth.43.186

Industrial health

Ind Health

The impact of sustained wakefulness and time-of-day on OSPAT performance.

Fatigue associated with shiftwork is a key contributor to human error in the workplace. One way to prevent fatigue-related errors from occurring is to identify fatigue in employees using fitness-for-duty measures. The Occupational Safety Performance Assessment Test (OSPAT), an unpredictable tracking task that measures hand-eye coordination, is currently being used as a fitness-for-duty measure in a variety of industries, but has not yet been validated as a test sensitive to the effects of fatigue. Consequently, the aim of this study was to systematically examine the impact of sustained wakefulness and time-of-day on OSPAT performance. Twenty individuals (10 male, 10 female), aged between 18-25 yr (M=20.90, SD=2.29) participated in the study, which was conducted in Australia. The study had a repeated measures design, whereby participants completed the OSPAT and measures of sustained attention (i.e., the psychomotor vigilance task: PVT), and subjective alertness (i.e., the Visual Analog Scale: VAS) every 2 h during 24 h of sustained wakefulness, beginning at 07:00 h. Results revealed that VAS ratings of alertness, PVT performance, and OSPAT performance declined significantly as hours of wakefulness increased during the night-time (all p<.01). Furthermore, a positive correlation between OSPAT and PVT performance was observed (r=0.40, p<.01). Overall, these findings suggest that OSPAT is sensitive to sustained wakefulness during the night-time, and builds the case for OSPAT being a suitable measure for determining fitness-for-duty in workplace environments.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1517/14656566.6.1.115

Expert opinion on pharmacotherapy

Expert Opin Pharmacother

Modafinil: new indications for wake promotion.

In January 2004, the wake-promoting agent, modafinil, was approved in the US for the treatment of excessive sleepiness (ES) associated with obstructive sleep apnoea/hypopnoea syndrome (OSAHS) and shift-work sleep disorder (SWSD), representing an expansion of its labelling from the initial indication for ES associated with narcolepsy. A total of five randomised, placebo-controlled studies in these three disorders showed statistically significant benefits on various objective measures and subjective estimates of ES, including the Multiple Sleep Latency Test, Maintenance of Wakefulness Test, Epworth Sleepiness Scale and Karolinska Sleepiness Scale. Significant improvement was also seen in overall clinical condition (on the Clinical Global Impression of Change) and measures of sustained attention and reaction time (on the Psychomotor Vigilance Task). The clinical efficacy of modafinil, combined with improved safety over CNS stimulants, has made it the most prescribed medication for the treatment of ES associated with narcolepsy. Modafinil is the only medication approved for ES associated with OSAHS and SWSD (for OSAHS, it is indicated as an adjunct to standard treatments for the under-lying obstruction). Unlike many other medications used for ES, modafinil is not known to be abused. The most common adverse event reported in clinical studies was headaches; most were transient and mild-to-moderate in severity. Modafinil also has the potential for interactions with other drugs metabolised via cytochrome P450 enzyme pathways. Potential obstacles to the use of modafinil include an under-recognition of ES and its consequences. Increased education, both of the public and the medical community, should improve the recognition and therapy of ES.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/28.1.93

Sleep

Sleep

Daytime sleep and performance following a zolpidem and melatonin cocktail.

Pharmacologic enhancement of daytime sleep may help sustain optimal cognitive performance. At effective doses, zolpidem induces sleep but also impairs performance. Combining melatonin with low-dose zolpidem may promote daytime sleep without exacerbating performance impairments seen with high-dose zolpidem alone. Following an 8-hour undisturbed nighttime sleep period, 80 subjects (50 men, 30 women) were administered oral zolpidem 0, 5, 10, or 20 mg at 10:00 am (n = 20 per group) and then oral melatonin 0 or 5 mg at 10:30 am (thus, n = 10 per drug combination) in a double-blind randomized fashion. Subjects napped from 10:00 am to 11:30 am, at which time they were awakened and cognitive tests administered (Restricted Reminding, Paired-Associates, and Psychomotor Vigilance). A second nap ensued from 12:45 pm to 4:00 pm, followed immediately by further testing. Melatonin 5 mg plus zolpidem 0 mg enhanced daytime sleep (P < .05) with no memory or performance impairment (P > .05). Zolpidem 20 mg plus melatonin 0 mg also enhanced daytime sleep (albeit nonsignificantly), but memory and vigilance were impaired (P < .05). Melatonin's sleep-promoting effects were not evident until the second nap. No advantages to administering melatonin plus zolpidem "cocktails" were evident. Unlike zolpidem, melatonin 5 mg alone improved daytime sleep without impairing memory and vigilance. Functional coupling of sleep-inducing and memory-impairing effects may be specific to benzodiazepine-receptor agonists such as zolpidem, suggesting potential advantages to using melatonin in the operational environment. That melatonin's sleep-promoting effects were delayed for several hours presents a practical consideration that may limit melatonin's usefulness when daytime sleep periods cannot be reliably anticipated or planned in advance.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Caffeine maintains vigilance and marksmanship in simulated urban operations with sleep deprivation.

The purpose of this study was to examine the effects of caffeine (CAF) on physical, vigilance, and marksmanship tasks in soldiers during a sustained 55-h field exercise. There were 30 soldiers (23.6 +/- 4.5 yr, 81.8 +/- 10.3 kg) who were divided into a placebo (PLAC) and a CAF group. After a period of restricted sleep of 3 h during the first night, a period of sustained wakefulness began that ended at 11:00 of the third day. PLAC or CAF doses of 100 mg, 200 mg, 100 mg, and 200 mg were administered at 21:45, 23:45, 01:45, and 03:45, respectively. At 22:00 of day 2, subjects began two cycles of marksmanship, urban operations vigilance, and psychomotor vigilance (PVT) testing which ended at 06:00 of day 3. CAF maintained marksmanship vigilance at 85% throughout the second night as compared with PLAC, who significantly declined to 61.4 +/- 28.2% overnight. Marksmanship accuracy also decreased significantly in PLAC from 95.1 +/- 8.3% to 83.3 +/- 19.2%, but no change was observed in CAF. Urban operations vigilance decreased for both groups over the night, but the decrease was less for CAF (81.2 +/- 14.4% to 63.4 +/- 24.1%) compared with PLAC (77.6 +/- 19.2% to 44.0 +/- 30.2%). Reaction time and the number of major and minor lapses with the PVT significantly increased in PLAC but were unaffected in CAF. It was concluded that CAF was an effective strategy to sustain vigilance and psychomotor performance during military operations involving sleep deprivation.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.2466/pms.99.3.739-753

Perceptual and motor skills

Percept Mot Skills

Performance on a dual driving simulation and subtraction task following sleep restriction.

A novel task, combining simulated driving with subtraction, was compared in 26 participants ages 18 to 26 years (M=20.6, SD=2.3; 13 men). After two nights of 8.5 hr. in bed, participants performed a 30-min. driving and subtraction task followed by a 10-min. Psychomotor Vigilance Task. These tasks were repeated after two more nights of 8.5 hr. time in bed for the control group and 5 hours and 3 hours time in bed for the restricted group. The sensitivity of the task to moderate sleep loss was supported because impairment was seen on several dual-task variables whereas impairment was not observed on the Psychomotor Vigilance Task.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3758/bf03195580

Behavior research methods, instruments, & computers : a journal of the Psychonomic Society, Inc

Behav Res Methods Instrum Comput

The validity of psychomotor vigilance tasks of less than 10-minute duration.

The 10-min psychomotor vigilance task (PVT) has often been used to assess the impact of sleep loss on performance. Due to time constraints, however, regular testing may not be practical in field studies. The aim of the present study was to examine the suitability of tests shorter than 10 min. in duration. Changes in performance across a night of sustained wakefulness were compared during a standard 10-min PVT, the first 5 min of the PVT, and the first 2 min of the PVT. Four performance metrics were assessed: (1) mean reaction time (RT), (2) fastest 10% of RT, (3) lapse percentage, and (4) slowest 10% of RT. Performance during the 10-min PVT significantly deteriorated with increasing wakefulness for all metrics. Performance during the first 5 min and the first 2 min of the PVT deteriorated in a manner similar to that observed for the whole 10-min task, with all metrics except lapse percentage displaying significant impairment across the night. However, the shorter the task sampling time, the less sensitive the test is to sleepiness. Nevertheless, the 5-min PVT may provide a viable alternative to the 10-min PVT for some performance metrics.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.sleep.2004.05.003

Sleep medicine

Sleep Med

The impact of extended sleep on daytime alertness, vigilance, and mood.

To measure the effects of prolonged sleep extension on daytime alertness, vigilance, and mood in healthy young adults. Little research has documented the effects of increased sleep on daytime function despite a high prevalence of daytime fatigue and sleepiness in the adult population. Past extension studies report conflicting results with regard to Multiple Sleep Latency Test (MSLT) scores, vigilance, and mood ratings. No study has challenged subjects to maximum sleep extension, defined by an MSLT score of 20. Fifteen healthy college students reporting minimal daytime sleepiness were allowed to sleep as much as possible during a sleep extension period. MSLT scores, psychomotor vigilance task (PVT) reaction times, and profile of mood states (POMS) ratings were measured at baseline, mid-extension, and end-extension. There was a significant increase in both journal and actigraphy sleep totals during all extension segments (P<0.01). MSLT scores increased significantly from baseline to both mid- and end-extension (P<0.01). Five of eight tabulated PVT measures also improved significantly at mid- and end-extension with respect to baseline (P<0.05). POMS vigor and fatigue scores showed a similar improvement (P<0.01). Seven subjects achieved an MSLT score of 20. Six subjects showed substantial improvements while two subjects obtained relatively little extra sleep and showed little or no MSLT improvement. The maximum extension group displayed exceptional improvements in vigilance and POMS ratings. Extended sleep leads to substantial improvements in daytime alertness, reaction time, and mood.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2004.00407.x

Journal of sleep research

J Sleep Res

Comparative utility of instruments for monitoring sleepiness-related performance decrements in the operational environment.

As both military and commercial operations increasingly become continuous, 24-h-per-day enterprises, the likelihood of operator errors or inefficiencies caused by sleep loss and/or circadian desynchrony also increases. Avoidance of such incidents requires the timely application of appropriate interventions--which, in turn, depend on the ability to measure and monitor the performance capacity of individuals in the operational environment. Several factors determine the potential suitability of candidate measures, including their relative sensitivity, reliability, content validity, intrusiveness and cumbersomeness/fieldability. In the present study, the relative sensitivity (defined as the ratio of effect size to 95% confidence interval) of several measures to the effects of sleep loss was compared in a sleep restriction experiment, in which groups were allowed 3, 5, 7, or 9 h time in bed (TIB) across seven consecutive nights. Of the measures compared, the Psychomotor Vigilance Test was among the most sensitive to sleep restriction, was among the most reliable with no evidence of learning over repeated administrations, and possesses characteristics that make it among the most practical for use in the operational environment.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1183/09031936.04.00091903

The European respiratory journal

Eur Respir J

Performance vigilance task and sleepiness in patients with sleep-disordered breathing.

Altered vigilance performance has been documented in patients with sleep-related breathing disorders (SRBDs). Sleep fragmentation, sleepiness, respiratory disturbances and nocturnal hypoxaemia have been suggested as the pathogenesis of these deficits, yet it remains difficult to find a good correlation between performance deficits and the above factors. In the present study, which performance measure better characterised SRBD patients and the main factors implicated in these disturbances were examined. The study group consisted of 152 patients and 45 controls, all examined using a performance vigilance task and subjective sleepiness assessment. Speed and accuracy in the psychomotor vigilance task (PVT) were measured in patients and controls. Objective daytime sleepiness was assessed in the patient group using the maintenance of wakefulness test. In comparison with controls, PVT accuracy rather than speed seems to be affected in SRBD patients, with lapses and false responses significantly greater in patients with more severe objective sleepiness and higher apnoea/hypopnoea index. Although slowing and increased variability in reaction time were associated with shorter sleep latency in the maintenance of wakefulness test, subjective sleepiness, sleep fragmentation, nocturnal hypoxaemia and apnoea/hypopnoea index influenced mainly PVT accuracy. It is concluded that vigilance impairment, sleep fragmentation and severity of disease may partially and differentially contribute to the diurnal performance consequences found in sleep-related breathing disorders. Since the psychomotor vigilance task worsening is more marked in accuracy that in speed, measurement of lapses and false responses would better characterise the degree of diurnal impairment in these patients.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/27.3.434

Sleep

Sleep

Modafinil improves alertness, vigilance, and executive function during simulated night shifts.

To assess the effect of 200 mg of modafinil compared to placebo on alertness, neurobehavioral performance, and executive function during 4 consecutive simulated night shifts. Double-blind, randomized, parallel groups. Sleep research facility. 32 male and female volunteers between the ages of 18 and 55 years. 200 mg of modafinil or placebo given nightly on the 4 consecutive simulated night shifts. Subjects were randomly assigned to 1 of the 2 treatment conditions, following medical, psychiatric, and polysomnographic screening. On 4 consecutive nights, subjects took study drug at 2200, and then from about 2300 to 0730 participated in a simulated night shift that included the Maintenance of Wakefulness Test, Psychomotor Vigilance Test, Digit Symbol Substitution Test, measures of subjective alertness, and multiple executive-function measures. At 0800, daytime sleep periods were recorded polysomnographically for 6 to 8 hours. Alertness--as measured by the MWT, vigilance and reaction time as indexed by Psychomotor Vigilance Test lapses, and slowest 10% of reaction times--and 3 executive-function tasks showed significant enhancement with modafinil versus placebo. Subjective sleepiness at night and some performance measures did not show consistent treatment differences. Daytime sleep showed minimal differences between conditions. The physiologic sleepiness and neurobehavioral deficits that occurred during the hours of a typical night shift were clearly attenuated by modafinil. Modafinil also had beneficial effects on some measures of executive function.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1210/jc.2003-031562

The Journal of clinical endocrinology and metabolism

J Clin Endocrinol Metab

Adverse effects of modest sleep restriction on sleepiness, performance, and inflammatory cytokines.

Total sleep restriction in humans is associated with increased daytime sleepiness, decreased performance, and hormonal/metabolic disturbances. The effects of mild chronic sleep restriction that mimic real life are not known. To assess the effects of modest sleep restriction from 8 to 6 h/night for 1 wk, 25 young, healthy, normal sleepers (12 men and 13 women) were studied for 12 consecutive nights in the sleep laboratory. After 1 wk of sleep restriction, although subjects' nighttime sleep was deeper, subjects were significantly sleepier (multiple sleep latency test) and performed worse in four primary variables of psychomotor vigilance test (both P < 0.01). Furthermore, 24-h secretion of IL-6 was increased by 0.8 +/- 0.3 pg/ml (P < 0.05) in both sexes, whereas TNFalpha was increased only in men. Also, the peak cortisol secretion was lower after sleep restriction than at baseline, and this difference was stronger in men (55.18 +/- 24.83 nmol/liter; P < 0.05) than in women (35.87 +/- 24.83 nmol/liter; P < 0.16). We conclude that in young men and women, modest sleep loss is associated with significant sleepiness, impairment of psychomotor performance, and increased secretion of proinflammatory cytokines. Given the potential association of these behavioral and physical alterations with health, well-being, and public safety, the idea that sleep or parts of it are optional should be regarded with caution.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Visual neglect: occurrence and patterns in pilots in a simulated overnight flight.

Visual neglect is the unconscious inability to recognize or acknowledge some visual information in the presence of a structurally intact visual system, and was hypothesized to occur with less than 24 h of continuous wakefulness. Visual perception was evaluated in military pilots during a simulated overnight flight to explore for the possible occurrence of visual neglect. There were eight military pilots (male, 31-52 yr of age, mean 37 yr) on flight status who were recruited to perform the primary task of flying a simulated 12.5 h overnight mission after a day of continuous wakefulness and the secondary task of responding to repeated 20 min presentations of single- and double-light stimuli displayed in random sequence at 15 degrees intervals across the cockpit instrument panel. In addition to the visual performance task, simulator shutdowns occurring when the tolerances of the simulator were exceeded were measured and simple reaction time on the psychomotor vigilance task was assessed. Total continuous wakefulness was 26.5 h. Combined performance on the visual perception task showed response omissions increasing at 19 h of continuous wakefulness. Patterns included omissions at all stimulus locations, of primarily peripherally located stimuli, and of one of two simultaneously presented stimuli. Simulator shutdowns began at 21.5 h of continuous wakefulness. Correlation of visual task response omissions with simulator shutdowns was r = 0.95, p < 0.0001. Significant neglect of visual stimuli occurred in pilots beginning at 19 h of continuous wakefulness in a simulated overnight fixed wing aircraft flight, preceded simulator shutdowns, and correlated at 0.95 with simulator shutdowns.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.physbeh.2003.12.004

Physiology & behavior

Physiol Behav

Circadian and wake-dependent modulation of fastest and slowest reaction times during the psychomotor vigilance task.

Performance on the psychomotor vigilance task (PVT) sensitively reflects a circadian modulation of neurobehavioral functions, as well as the effect of sleep pressure developing with duration of time awake, without being confounded by a learning curve. Sixteen healthy volunteers underwent two 40-h constant posture protocols in a balanced crossover design. During these protocols, either low sleep pressure conditions were attained by an alternating cycle of 150 min of wakefulness and 75 min of sleep (NAP) protocol, or high sleep pressure conditions were achieved by total sleep deprivation (SD) protocol. During scheduled wakefulness in both protocols, the PVT was carried out every 225 min. Quantitative analysis of the lapses, slowest (90th percentile) and fastest (10th percentile) reaction times (RTs) during the protocols, indicated that the lapses and slowest RTs were sensitive to changes in homeostatic sleep pressure. Our data indicate that the difference between the fastest and slowest RTs (interpercentile range 10th-90th percentile) was particular sensitive to detect very early effects of growing sleep pressure. On the other hand, decrements in PVT performance which were related to circadian phase did not depend significantly on any categorization (such as percentiles of the RTs).

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/26.8.981

Sleep

Sleep

Ethanol and sleep loss: a "dose" comparison of impairing effects.

Studies to assess the risks associated with sleep loss relative to the well-documented risks of alcohol are limited in number and design. This study compared the "dose"-related sedative, performance-impairing, and amnestic effects of sleep loss to those of ethanol ingestion. Mixed-design experiment with random assignment to a sleep loss (n=12) or ethanol (n=20) group, with each participant assessed under 4 conditions. Thirty-two healthy normal adult volunteers, aged 21 to 35 years. In sleep loss, participants had 8, 6, 4, and 0 hours time in bed, producing 0, 2, 4, and 8 hours of sleep loss. For ethanol, participants ingested 0.0 g/kg, 0.3 g/kg, 0.6 g/kg, and 0.9 g/kg ethanol from 8:30 AM to 9:00 AM after 8 hours of time in bed the previous night. Each participant received his or her 4 doses of ethanol or sleep loss in a Latin square design with 3 to 7 days between doses. All subjects completed the Multiple Sleep Latency Test (MSLT) at 9:30 AM, 11:30 AM, 1:30 PM, 3:30 PM, and 5:30 PM and a performance battery at 10:00 AM, 12:00 NOON, 2:00 PM, and 4:00 PM consisting of memory, psychomotor vigilance, and divided attention tests. Ethanol and sleep loss reduced the average daily sleep latency on the MSLT, both as a linear function of dose, with sleep loss in hours being 2.7 times more potent than ethanol in grams per kilogram. Ethanol and sleep loss also slowed reaction time on the psychomotor vigilance test in a linear dose-related function with the 2 being equipotent in their impairing effect. On the divided attention test, tracking deviations were increased by both ethanol and sleep loss in an equipotent and linear dose-related function. Memory recall was reduced in a linear dose-related function by both ethanol and sleep loss with ethanol being slightly more potent. Finally, sleep loss doses produced a linear decrease in self-rated quality of performance, while only at the highest ethanol dose was performance rated as poorer. At the studied doses, sleep loss was more potent than ethanol in its sedative effects but comparable in effects on psychomotor performance. Ethanol produced greater memory deficits, and subjects were less aware of their overall performance impairment.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/00140130310001617930

Ergonomics

Ergonomics

Adaptation of performance during a week of simulated night work.

This study aimed to provide a comparative index of the performance impairment associated with the fatigue levels frequently experienced in workplaces that require night work. To do this, we equated fatigue-related impairment with the impairment resulting from varying levels of alcohol intoxication. Fifteen young individuals participated in two counterbalanced conditions which required them to (1). 'work' seven consecutive 8-h night shifts, and (2). consume an alcoholic beverage at hourly intervals until their blood alcohol concentration (BAC) reached 0.10%. In each condition, performance was measured at hourly intervals using a 10-min psychomotor vigilance task (PVT). Analysis indicated that as BAC increased, performance impairment significantly increased. Similarly, response times significantly increased during the first six simulated night-shifts, and lapse frequency significantly increased during the first two shifts. Equating the two conditions indicated that the first simulated night shift was associated with the greatest degree of performance impairment. In general, the impairment at the end of this shift was greater than that observed at a BAC of 0.10%. During the second and third simulated night shifts, the performance impairment was less than on the first night, but greater than that observed at a BAC of 0.05%. For the final four nights, the performance decrements generally did not exceed those observed at a BAC of 0.05%. This suggests that during a week of consecutive night shifts, adaptation of performance occurs.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/26.7.871

Sleep

Sleep

The ability to self-monitor performance during a week of simulated night shifts.

Research has indicated that individuals are able to accurately monitor the performance decrements they experience during unitary periods of acute sleep deprivation. The aim of the current study was to investigate the ability to self-monitor performance during a week of simulated night shifts. Subjects completed 7 consecutive 8-hour night shifts (11 pm-7 am). University sleep laboratory. Fifteen young (7 men, 8 women, 19-25 years) healthy volunteers. During the night shifts, performance was measured hourly on 4 performance parameters: psychomotor vigilance test (PVT), tracking, and grammatical reasoning (GRG) accuracy and response latency. Before and after each test, subjects completed visual analogue scales, which required them to rate their alertness and their performance speed and/or accuracy. Analysis indicated that GRG response latency and tracking were significantly impaired (P<0.05) during the first 2 shifts only. The PVT performance displayed consistent impairment, with significant (P<0.05) declines during all but the final shift. The pattern of deterioration in subjective ratings of alertness was similar to that of the PVT data. Correlations between subjective alertness and self-ratings of performance were significant (P<0.01) for all parameters (r=0.39-0.69). Significant (P<0.05) correlations were found across the week between pretest performance ratings and actual performance for all parameters except GRG accuracy (r=0.29-0.58) and between posttest ratings and actual performance for all parameters (r=0.52-0.75). Correlations between pretest ratings and actual performance were also conducted separately for each shift. Highest correlations were found during the first shift, with r-values that were low for GRG accuracy (r=0.32) and GRG response latency (r=0.20), moderate for tracking (r=0.41), and high for PVT (r=0.82). In general, lower correlations were found later in the week. Overall, results indicate that individuals have only a moderate ability to predict performance impairment during a week of night shifts. It is likely that performance ratings are based, at least to a certain extent, on subjective alertness levels. Furthermore, it seems that rating accuracy is improved on tasks providing performance feedback, such as the PVT. Finally, it appears that after testing, individuals have a more accurate perception of their performance.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/s1389-9457(03)00108-4

Sleep medicine

Sleep Med

Effects of modafinil on sustained attention performance and quality of life in OSA patients with residual sleepiness while being treated with nCPAP.

Some patients with obstructive sleep apnea/hypopnea syndrome (OSA/HS) who are regular users of nasal continuous positive airway pressure (nCPAP) therapy continue to experience daytime sleepiness that impairs performance and quality of life. A randomized, double-blind, placebo-controlled, parallel-group study was conducted to determine the effect of modafinil on sustained attention performance and functional quality of life in OSA/HS patients with residual daytime sleepiness, who were regular users of nCPAP therapy. Seventy-seven patients received modafinil (200 mg/day, week 1; 400 mg/day, weeks 2-4) and 80 patients received matching placebo once daily for 4 weeks. Sustained attention performance on the psychomotor vigilance task (PVT) and functional status and quality of life using the Functional Outcomes of Sleep Questionnaire (FOSQ) were measured. The frequency of lapses of attention during PVT performance was significantly decreased, and both the median and slowest reaction times were significantly improved in patients receiving nCPAP plus modafinil compared with those receiving nCPAP plus placebo (P=0.010 for the number of lapses [transformed], P=0.023 for the median reaction time, and P=0.014 for the reciprocal of the 10% slowest reaction times). Treatment with nCPAP plus modafinil significantly improved the FOSQ total score (weeks 1 and 4), the vigilance subscale score (weeks 1 and 4), and the activity level subscale score (week 4) compared with treatment with nCPAP plus placebo (all P<0.05). Consistent with previous results for objective and subjective measures of sleepiness, modafinil used adjunctively improved performance on a test of behavioral alertness and reduced functional impairments in patients with OSA/HS who were regular users of nCPAP therapy but still experiencing sleepiness.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1136/oem.60.11.e13

Occupational and environmental medicine

Occup Environ Med

The impact of a week of simulated night work on sleep, circadian phase, and performance.

To investigate factors that may contribute to performance adaptation during permanent night work. Fifteen healthy subjects participated in an adaptation and baseline night sleep, directly followed by seven simulated eight-hour night shifts (2300 to 0700 hours). At the end of each shift they were taken outside and exposed to natural light for 20 minutes. They then slept from approximately 0800 hours until they naturally awoke. There was a significant increase in mean performance on a visual psychomotor vigilance task across the week. Daytime sleep quality and quantity were not negatively affected. Total sleep time (TST) for each of the daytime sleeps was reduced, resulting in an average cumulative sleep debt of 3.53 hours prior to the final night shift. TST for each of the daytime sleep periods did not significantly differ from the baseline night, nor did TST significantly vary across the week. There was a significant decrease in wake time after sleep onset and sleep onset latency across the week; sleep efficiency showed a trend towards greater efficiency across the consecutive daytime sleeps. Hours of wakefulness prior to each simulated night shift significantly varied across the week. The melatonin profile significantly shifted across the week. Results suggest that under optimal conditions, the sleep debt that accumulates during consecutive night shifts is relatively small and does not exacerbate decrements in night-time performance resulting from other factors. When sleep loss is minimised, adaptation of performance during consecutive night shifts can occur in conjunction with circadian adaptation.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/26.6.695

Sleep

Sleep

Daytime exposure to bright light, as compared to dim light, decreases sleepiness and improves psychomotor vigilance performance.

This study examined the effects of bright light exposure, as compared to dim light, on daytime subjective sleepiness, incidences of slow eye movements (SEMs), and psychomotor vigilance task (PVT) performance following 2 nights of sleep restriction. The study had a mixed factorial design with 2 independent variables: light condition (bright light, 1,000 lux; dim light, < 5 lux) and time of day. The dependent variables were subjective sleepiness, PVT performance, incidences of SEMs, and salivary melatonin levels. Sleep research laboratory at Monash University. Sixteen healthy adults (10 women and 6 men) aged 18 to 35 years (mean age 25 years, 3 months). Following 2 nights of sleep restriction (5 hours each night), participants were exposed to modified constant routine conditions. Eight participants were exposed to bright light from noon until 5:00 pm. Outside the bright light exposure period (9:00 am to noon, 5:00 pm to 9:00 pm) light levels were maintained at less than 5 lux. A second group of 8 participants served as controls for the bright light exposure and were exposed to dim light throughout the entire protocol. Bright light exposure reduced subjective sleepiness, decreased SEMs, and improved PVT performance compared to dim light. Bright lights had no effect on salivary melatonin. A significant positive correlation between PVT reaction times and subjective sleepiness was observed for both groups. Changes in SEMs did not correlate significantly with either subjective sleepiness or PVT performance. Daytime bright light exposure can reduce the impact of sleep loss on sleepiness levels and performance, as compared to dim light. These effects appear to be mediated by mechanisms that are separate from melatonin suppression. The results may assist in the development of treatments for daytime sleepiness.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

La Medicina del lavoro

Med Lav

[Techniques for administering inhalation anesthetic agents, professional exposure, and early neurobehavioral effects].

Occupational exposure to high concentrations of anaesthetic gases can cause neurobehavioral effects in operating room personnel. The measures taken to reduce waste gas exposures, including the installation of active scavenging devices and airconditioning systems, are not effective, so that the NIOSH recommendations for maximum exposure are currently unattainable in practice. The aim of the present study was to measure operating room pollution and neurobehavioral functions in a group of anaesthesiologists during open-system and low-flow anaesthesia. Environmental concentrations of N2O and isoflurance were measured by an infrared gas analyzer (Brüel & Kjaer) in open system and in low flow anaesthesia. Under the same stress condition, but with different exposure levels to anaesthetic gases, psychomotor vigilance and response speed were evaluated four times with the Reaction Time Test at the beginning and at the end of the first weekday shift and at the beginning and at the end of the last weekday shift. Exclusion criteria were considered excessive alcohol and coffee intake and use of CNS medication. Concentrations of N2O and isoflurane in the operating room were 4.83 ppm and 0.4 ppm respectively, which are lower compared with open systems: 301 ppm and 11.1 ppm respectively. The mean of the Reaction Time was significantly higher (p < 0.01) during work with the open system compared to work in low flow at the end of the first weekday shift and at the end of the last weekday shift. Low-flow anaesthesia appears to be effective in reducing waste gas exposure: lower flows produced lower values and protect the integrity of neurobehavioral functions.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1046/j.1365-2869.2003.00337.x

Journal of sleep research

J Sleep Res

Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: a sleep dose-response study.

Daytime performance changes were examined during chronic sleep restriction or augmentation and following subsequent recovery sleep. Sixty-six normal volunteers spent either 3 (n = 18), 5 (n= 16), 7 (n = 16), or 9 h (n = 16) daily time in bed (TIB) for 7 days (restriction/augmentation) followed by 3 days with 8 h daily TIB (recovery). In the 3-h group, speed (mean and fastest 10% of responses) on the psychomotor vigilance task (PVT) declined, and PVT lapses (reaction times greater than 500 ms) increased steadily across the 7 days of sleep restriction. In the 7- and 5-h groups speed initially declined, then appeared to stabilize at a reduced level; lapses were increased only in the 5-h group. In the 9-h group, speed and lapses remained at baseline levels. During recovery, PVT speed in the 7- and 5-h groups (and lapses in the 5-h group) remained at the stable, but reduced levels seen during the last days of the experimental phase, with no evidence of recovery. Speed and lapses in the 3-h group recovered rapidly following the first night of recovery sleep; however, recovery was incomplete with speed and lapses stabilizing at a level comparable with the 7- and 5-h groups. Performance in the 9-h group remained at baseline levels during the recovery phase. These results suggest that the brain adapts to chronic sleep restriction. In mild to moderate sleep restriction this adaptation is sufficient to stabilize performance, although at a reduced level. These adaptive changes are hypothesized to restrict brain operational capacity and to persist for several days after normal sleep duration is restored, delaying recovery.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Improving daytime sleep with temazepam as a countermeasure for shift lag.

Working night shift (reverse cycle) presents problems to personnel due to the difficulty in maintaining alertness during the nighttime hours. When the shift must be worked several consecutive nights, a cumulative sleep debt is created. Appropriate countermeasures are required to help personnel obtain as much sleep as possible so they may perform their duties effectively. The objectives were to determine whether a hypnotic taken before daytime sleep would improve sleep quality, and to determine whether improved daytime sleep would increase alertness, reduce fatigue, and mitigate the usual performance decrements which occur on night shift. Sixteen UH-60 Army aviators were randomly assigned to either a temazepam or a placebo group. Test sessions, consisting of vigilance assessments, flight simulation, and mood state questionnaires were administered during baseline, three nights of reverse cycle, and three days following a return to day shift. Temazepam (30 mg) was administered before daytime sleep to one group while another group received a lactose-filled capsule. Subjects who received temazepam slept longer and with less fragmentation than those who received placebo. Generally, the subjects in the temazepam group indicated more subjective alertness and less fatigue than those in the placebo group. Flight performance was not unequivocally improved by better daytime sleep, but the temazepam group performed better on the Psychomotor Vigilance Task than the placebo group. Temazepam is helpful in prolonging daytime sleep, with some attenuation of performance decrements during the night shift. However, physicians should be careful when administering this substance to ensure the aviator has a minimum of 8 h in which to sleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/s1388-2457(02)00283-3

Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology

Clin Neurophysiol

Body posture affects electroencephalographic activity and psychomotor vigilance task performance in sleep-deprived subjects.

This study examined the effects of posture on electroencephalographic (EEG) activity and psychomotor vigilance task (PVT) performance in 16 sleep-deprived volunteers. EEG data were collected while participants completed 10 min PVTs under two counterbalanced sitting/standing conditions during 28 h of continuous wakefulness. In both the sitting and standing conditions, theta activity progressively increased as a function of sleep loss, but standing upright significantly attenuated this effect, suggesting that alertness was improved by the more upright posture. The PVT results showed that cognitive psychomotor performance was maintained at nearly well-rested levels by standing upright, whereas reaction time and attention noticeably deteriorated when participants were seated. These results suggest that an upright posture increases EEG arousal and sustained attention, indicating that postural manipulations can be useful for counteracting fatigue in sleep-deprived individuals.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/1469-8986.3860979

Psychophysiology

Psychophysiology

Effects of rapid versus slow accumulation of eight hours of sleep loss.

The present study assessed alertness, memory, and performance following three schedules of approximately 8 hr of sleep loss (slow, intermediate, and rapid accumulation) in comparison to an 8-hr time in bed (TIB) sleep schedule. Twelve healthy individuals aged 21-35 completed each of four conditions according to a Latin Square design: no sleep loss (8-hr TIB for 4 nights; 2300-0700), slow (6-hr TIB for 4 nights; 0100-0700), intermediate (4-hr TIB for 2 nights; 0300-0700), and rapid (0-hr TIB for 1 night) sleep loss. On each day, participants completed a multiple sleep latency test (MSLT), a probed-recall memory task, a psychomotor vigilance task, a divided attention task, and the Profile of Mood States. "Rapid" sleep loss produced significantly more impairment on tests of alertness, memory, and performance compared to the "slow" accumulation of a comparable amount of sleep loss. The impairing effects of sleep loss vary as a function of rate, suggesting the presence of a compensatory adaptive mechanism operating in conjunction with the accumulation of a sleep debt.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Controlled breaks as a fatigue countermeasure on the flight deck.

A major challenge for flight crews is the need to maintain vigilance during long, highly automated nighttime flights. No system currently exists to assist in managing alertness, and countermeasure options are limited. Surveys reveal many pilots use breaks as an in-flight countermeasure, but there have been no controlled studies of their effectiveness. We hypothesized that brief, regular breaks could improve alertness and performance during an overnight flight. A 6-h, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected. During the latter part of the night, the treatment group showed significant reductions for 15 min post-break in slow eye movements, theta-band activity, and unintended sleep episodes compared with the control group. The treatment group reported significantly greater subjective alertness for up to 25 min post-break, with strongest effects near the time of the circadian trough. There was no evidence of objective vigilance performance improvement at 15-25 min post-break, with expected performance deterioration occurring due to elevated sleep drive and circadian time. The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/24.7.813

Sleep

Sleep

Caffeine eliminates psychomotor vigilance deficits from sleep inertia.

This study sought to establish the effects of caffeine on sleep inertia, which is the ubiquitous phenomenon of cognitive performance impairment, grogginess and tendency to return to sleep immediately after awakening. 28 normal adult volunteers were administered sustained low-dose caffeine or placebo (randomized double-blind) during the last 66 hours of an 88-hour period of extended wakefulness that included seven 2-hour naps during which polysomnographical recordings were made. Every 2 hours of wakefulness, and immediately after abrupt awakening from the naps, psychomotor vigilance performance was tested. N/A. N/A. N/A. In the placebo condition, sleep inertia was manifested as significantly impaired psychomotor vigilance upon awakening from the naps. This impairment was absent in the caffeine condition. Caffeine had only modest effects on nap sleep. Caffeine was efficacious in overcoming sleep inertia. This suggests a reason for the popularity of caffeine-containing beverages after awakening. Caffeine's main mechanism of action on the central nervous system is antagonism of adenosine receptors. Thus, increased adenosine in the brain upon awakening may be the cause of sleep inertia.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/00140130119824

Ergonomics

Ergonomics

A quantitative model of work-related fatigue: empirical evaluations.

Systematic and quantitative management of work-related fatigue within workplaces has been a challenging task due to a lack of useful tools. A previous paper provided background and development of a work-related fatigue modelling approach. The current paper outlines model evaluations using sleep deprivation experiments and recommendations of work scheduling. Previous studies have reported cumulative effects of sleep restriction (4-5 h per night) on a number of measures. Model predictions were correlated against psychomotor vigilance task lapses (r = 0.92) and reaction time responses (slowest 10%, r = 0.91) as well as sleep latency (r = -0.97). Further correlations were performed on four measures from a 64 h continuous sleep deprivation study; that is objective vigilance (r = -0.75) as well as subjective performance (r = -0.75), sleepiness (r = 0.82) and tiredness (r = 0.79). Evaluation against current scheduling recommendations illustrated consistency with the literature with the exception that forward rotation did not provide benefits over backward rotation. The results indicate that model predictions correlate well across a range of objective and subjective measures. This relationship also appears to hold for cumulative and continuous sleep deprivation protocols. Future studies will also focus on field-based evaluation.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Archives italiennes de biologie

Arch Ital Biol

Sustained attention performance during sleep deprivation: evidence of state instability.

Nathaniel Kleitman was the first to observe that sleep deprivation in humans did not eliminate the ability to perform neurobehavioral functions, but it did make it difficult to maintain stable performance for more than a few minutes. To investigate variability in performance as a function of sleep deprivation, n = 13 subjects were tested every 2 hours on a 10-minute, sustained-attention, psychomotor vigilance task (PVT) throughout 88 hours of total sleep deprivation (TSD condition), and compared to a control group of n = 15 subjects who were permitted a 2-hour nap every 12 hours (NAP condition) throughout the 88-hour period. PVT reaction time means and standard deviations increased markedly among subjects and within each individual subject in the TSD condition relative to the NAP condition. TSD subjects also had increasingly greater performance variability as a function of time on task after 18 hours of wakefulness. During sleep deprivation, variability in PVT performance reflected a combination of normal timely responses, errors of omission (i.e., lapses), and errors of commission (i.e., responding when no stimulus was present). Errors of omission and errors of commission were highly intercorrelated across deprivation in the TSD condition (r = 0.85, p = 0.0001), suggesting that performance instability is more likely to include compensatory effort than a lack of motivation. The marked increases in PVT performance variability as sleep loss continued supports the "state instability" hypothesis, which posits that performance during sleep deprivation is increasingly variable due to the influence of sleep initiating mechanisms on the endogenous capacity to maintain attention and alertness, thereby creating an unstable state that fluctuates within seconds and that cannot be characterized as either fully awake or asleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/s0166-4328(01)00158-9

Behavioural brain research

Behav Brain Res

Early morning melatonin administration impairs psychomotor vigilance.

The acute soporific effect of melatonin in humans has been demonstrated in a range of studies. How alertness and performance are changed after melatonin given in the morning is not yet known. In a double-blind, placebo-controlled study of nine healthy young men, melatonin was given at 0700 h under controlled conditions of a modified constant routine protocol lasting 56 h (2 days, 3 nights with sleep). A clear decrement in neurobehavioral functions as measured by the Psychomotor Vigilance Test lasted for 6 h after melatonin administration (particularly in the lapse domain and median of the reaction time) without any effect on a letter cancellation task. A subjective soporific effect was present but less pronounced. Thus, melatonin taken in the morning requires caution in situations where high attention is needed.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/s0031-9384(00)00322-x

Physiology & behavior

Physiol Behav

Effects of an experimentally induced rhinovirus cold on sleep, performance, and daytime alertness.

There is accumulating evidence that the common cold produces impairments in psychomotor vigilance. This has led some investigators to hypothesize that such illnesses may also have disruptive effects on sleep. While several self-report studies suggest that viral illness may influence sleep parameters, no studies have assessed polysomnographically recorded sleep following viral infections. Parallel control group comparison. Sleep laboratory in a large urban medical center. Twenty-one men and women with susceptibility to the rhinovirus type 23. Nasal inoculation with rhinovirus type 23. Polysomnographically recorded sleep for five nights (2300-0700 h) post-viral inoculation. Twice daily (1030 and 1430 h) performance assessment during each experimental day using auditory vigilance and divided attention tasks. A multiple sleep latency test (MSLT) was performed daily for the duration of the study. In symptomatic individuals, total sleep time decreased an average of 23 min, consolidated sleep decreased an average of 36 min, and sleep efficiency was reduced by an average of 5% during the active viral period (experimental days/nights 3-5) compared with the incubation period. Psychomotor performance was impaired. These changes were significantly greater than those observed in asymptomatic individuals. The common cold can have detrimental effects on sleep and psychomotor performance in symptomatic individuals during the initial active phase of the illness.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/s1388-2457(99)00258-8

Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology

Clin Neurophysiol

Test-retest reliability of cognitive EEG.

Task-related EEG is sensitive to changes in cognitive state produced by increased task difficulty and by transient impairment. If task-related EEG has high test-retest reliability, it could be used as part of a clinical test to assess changes in cognitive function. The aim of this study was to determine the reliability of the EEG recorded during the performance of a working memory (WM) task and a psychomotor vigilance task (PVT). EEG was recorded while subjects rested quietly and while they performed the tasks. Within session (test-retest interval of approximately 1 h) and between session (test-retest interval of approximately 7 days) reliability was calculated for four EEG components: frontal midline theta at Fz, posterior theta at Pz, and slow and fast alpha at Pz. Task-related EEG was highly reliable within and between sessions (r0.9 for all components in WM task, and r0.8 for all components in the PVT). Resting EEG also showed high reliability, although the magnitude of the correlation was somewhat smaller than that of the task-related EEG (r0.7 for all 4 components). These results suggest that under appropriate conditions, task-related EEG has sufficient retest reliability for use in assessing clinical changes in cognitive status.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1152/ajpregu.1999.277.4.r1152

The American journal of physiology

Am J Physiol

Circadian temperature and melatonin rhythms, sleep, and neurobehavioral function in humans living on a 20-h day.

The interaction of homeostatic and circadian processes in the regulation of waking neurobehavioral functions and sleep was studied in six healthy young subjects. Subjects were scheduled to 15-24 repetitions of a 20-h rest/activity cycle, resulting in desynchrony between the sleep-wake cycle and the circadian rhythms of body temperature and melatonin. The circadian components of cognitive throughput, short-term memory, alertness, psychomotor vigilance, and sleep disruption were at peak levels near the temperature maximum, shortly before melatonin secretion onset. These measures exhibited their circadian nadir at or shortly after the temperature minimum, which in turn was shortly after the melatonin maximum. Neurobehavioral measures showed impairment toward the end of the 13-h 20-min scheduled wake episodes. This wake-dependent deterioration of neurobehavioral functions can be offset by the circadian drive for wakefulness, which peaks in the latter half of the habitual waking day during entrainment. The data demonstrate the exquisite sensitivity of many neurobehavioral functions to circadian phase and the accumulation of homeostatic drive for sleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/22.2.171

Sleep

Sleep

Dose-response relationship between sleep duration and human psychomotor vigilance and subjective alertness.

Although it has been well documented that sleep is required for human performance and alertness to recover from low levels after prolonged periods of wakefulness, it remains unclear whether they increase in a linear or asymptotic manner during sleep. It has been postulated that there is a relation between the rate of improvement in neurobehavioral functioning and rate of decline of slow-wave sleep and/or slow-wave activity (SWS/SWA) during sleep, but this has not been verified. Thus, a cross-study comparison was conducted in which dose-response curves (DRCs) were constructed for Stanford Sleepiness Scale (SSS) and Psychomotor Vigilance Task (PVT) tests taken at 1000 hours by subjects who had been allowed to sleep 0 hours, 2 hours, 5 hours or 8 hours the previous night. We found that the DRCs to each PVT metric improved in a saturating exponential manner, with recovery rates that were similar [time constant (T) approximately 2.14 hours] for all the metrics. This recovery rate was slightly faster than, though not statistically significantly different from, the reported rate of SWS/SWA decline (T approximately 2.7 hours). The DRC to the SSS improved much more slowly than psychomotor vigilance, so that it could be fit equally well by a linear function (slope = -0.26) or a saturating exponential function (T = 9.09 hours). We conclude that although SWS/SWA, subjective alertness, and a wide variety of psychomotor vigilance metrics may all change asymptotically during sleep, it remains to be determined whether the underlying physiologic processes governing their expression are different.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Sleep

Sleep

Cumulative sleepiness, mood disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4-5 hours per night.

To determine whether a cumulative sleep debt (in a range commonly experienced) would result in cumulative changes in measures of waking neurobehavioral alertness, 16 healthy young adults had their sleep restricted 33% below habitual sleep duration, to an average 4.98 hours per night [standard deviation (SD) = 0.57] for seven consecutive nights. Subjects slept in the laboratory, and sleep and waking were monitored by staff and actigraphy. Three times each day (1000, 1600, and 2200 hours) subjects were assessed for subjective sleepiness (SSS) and mood (POMS) and were evaluated on a brief performance battery that included psychomotor vigilance (PVT), probed memory (PRM), and serial-addition testing, Once each day they completed a series of visual analog scales (VAS) and reported sleepiness and somatic and cognitive/emotional problems. Sleep restriction resulted in statistically robust cumulative effects on waking functions. SSS ratings, subscale scores for fatigue, confusion, tension, and total mood disturbance from the POMS and VAS ratings of mental exhaustion and stress were evaluated across days of restricted sleep (p = 0.009 to p = 0.0001). PVT performance parameters, including the frequency and duration of lapses, were also significantly increased by restriction (p = 0.018 to p = 0.0001). Significant time-of-day effects were evident in SSS and PVT data, but time-of-day did not interact with the effects of sleep restriction across days. The temporal profiles of cumulative changes in neurobehavioral measures of alertness as a function of sleep restriction were generally consistent. Subjective changes tended to precede performance changes by 1 day, but overall changes in both classes of measure were greatest during the first 2 days (P1, P2) and last 2 days (P6, P7) of sleep restriction. Data from subsets of subjects also showed: 1) that significant decreases in the MSLT occurred during sleep restriction, 2) that the elevated sleepiness and performance deficits continued beyond day 7 of restriction, and 3) that recovery from these deficits appeared to require two full nights of sleep. The cumulative increase in performance lapses across days of sleep restriction correlated closely with MSLT results (r = -0.95) from an earlier comparable experiment by Carskadon and Dement (1). These findings suggest that cumulative nocturnal sleep debt had a dynamic and escalating analog in cumulative daytime sleepiness and that asymptotic or steady-state sleepiness was not achieved in response to sleep restriction.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/0301-0511(95)05114-7

Biological psychology

Biol Psychol

Batch processing of 10,000 h of truck driver EEG data.

This paper describes the methods used to acquire and reduce a massive amount of EEG data (Wylie et al., 1990). The description is introduced by a review of a previous effort (Mackie and Miller, 1978). The earlier effort created much of the design philosophy for the second effort. The majority of data in the Paradox database came from 400 trips contributed by 80 commercial drivers driving both day and night revenue-cargo runs of 10 or 13 h each. The sleep and driving EEG data were collected with ambulatory Medilog recorders. Breathing and oxyhemoglobin measures were collected during sleep for sleep-apnea determinations. The sleep and driving-EEG data were placed in raw digitized files (128 samples/second), with the latter also available as compressed-band arrays for 20-s epochs, with associated Rechtschaffen and Kales (1968) manual scoring by polysomnographers for all EEG data. Sleep EEG, subjective driving performance and discrete-task data were also placed in the database, integrated and time-registered to within 1-s accuracy with the driving EEG data. Each truck was extensively instrumented for lateral lane position, steering wheel position, speed, video image of the roadway, and video image of the face. Each driver recorded body temperatures several times per day, provided Stanford Sleepiness Scale readings several times each day, and was connected to the Vagal Tone Monitor while driving. In addition, driving segments were prefaced and followed by the performance of the Critical Tracking Task, the Psychomotor Vigilance Task, and the Code Substitution Task. The database should serve as an international resource from which many investigators may draw data.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1164/ajrccm/147.5.1162

The American review of respiratory disease

Am Rev Respir Dis

Effects of one night without nasal CPAP treatment on sleep and sleepiness in patients with obstructive sleep apnea.

Nasal continuous positive airway pressure (CPAP) has become the nonsurgical treatment of choice for obstructive sleep apnea syndrome (OSAS). Recent evidence suggests that intermittent use of CPAP by patients is more common than nightly compliance. To determine the consequences of intermittent CPAP use, in terms of a return of sleep-disordered breathing and daytime hypersomnolence, 15 OSAS subjects were evaluated at three times: (1) before CPAP treatment (pretreatment), (2) after 30 to 237 days posttreatment during a night of CPAP use (on CPAP), and (3) during a night without CPAP (off CPAP). Evaluations of sleep-disordered breathing and three domains of hypersomnolence, physiologic sleep tendency, subjective sleepiness, and performance, were accomplished with the respiratory disturbance index (RDI), multiple sleep latency test (MSLT), Stanford sleepiness scale (SSS), and psychomotor vigilance task (PVT), respectively. CPAP use was encouraged and monitored from pretreatment to post-treatment by daily diaries for most subjects and an electronic device for a subset of subjects. As expected, CPAP eliminated apneas and hypopneas, and following the on CPAP night, there were statistically significant improvements in objective measures of sleepiness (MSLT and PVT). Subjective measures of sleepiness and fatigue also showed improvement. Sleeping without CPAP for one night reversed virtually all of the sleep and daytime alertness gains derived from sleeping with CPAP. This occurred despite a statistically significant reduction in the RDI on the night off CPAP (M = 36.8, SD = 28.0 events/h) relative to the pretreatment night (M = 56.6, SD = 24.8 events/h), which may be due to a lessening of the edema of the upper airway following CPAP use.(ABSTRACT TRUNCATED AT 250 WORDS)

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1007/s10578-021-01128-3

Child psychiatry and human development

Child Psychiatry Hum Dev

Do Patterns of Levels of Socio-emotional Competence During Early Childhood Predict Executive Function at 4.5 Years?

Socio-emotional competence and executive function both work together to meet the demands of the everyday environment. While many studies have focused on how various domains of socio-emotional competence are predicted by, or associated with executive function, the predictive influence of socio-emotional competence on executive function has largely been ignored despite strong theoretical links. In addition, contradictory information exists with regard to the divergent validity of two subtypes of executive function: cool and hot. Using data from 4839 children participating in three data collection waves (9 months, 2 years and 4.5 year) in the Growing Up in New Zealand longitudinal study, we examined how different patterns of socio-emotional competence development during the early preschool years (persistent lows, recent low, improved and no lows) related to cool and hot executive function measured at aged 4.5 using a hand clap task and a gift wrap task, respectively. Findings showed that children with persistent lows (with no improvement) in the levels of early socio-emotional competence had increased odds of having below average cool and hot executive function at 4.5 years. However, no difference was found in the influence of socio-emotional competence on cool and hot executive function. Possible explanations for these associations between socio-emotional competence and executive function are discussed.

CognitiveTask

GiftWrap

10.1111/jcpp.12889

Journal of child psychology and psychiatry, and allied disciplines

J Child Psychol Psychiatry

Sociodemographic risk, parenting, and inhibitory control in early childhood: the role of respiratory sinus arrhythmia.

Deficits of inhibitory control in early childhood are linked to externalizing behaviors and attention problems. While environmental factors and physiological processes are associated with its etiology, few studies have examined how these factors jointly predict inhibitory control. This study examined whether respiratory sinus arrhythmia (RSA) functioned as a mediator or moderator of both cumulative sociodemographic risk and parenting behaviors on inhibitory control during early childhood. The sample included 206 children and their biological mothers. At 24, 30, and 36 months of child age dyads participated in a series of laboratory visits in which sociodemographic, parenting, and baseline RSA (RSAB) data were collected. Inhibitory control was assessed at 36 months using a gift-wrap delay task. A series of structural equation models yielded no evidence that RSAB mediated the relations of risk or parenting and inhibitory control. RSAB moderated the effects of risk, such that high-risk children with low RSAB performed more poorly on tasks of inhibitory control, while high-risk children with high RSAB did not. These results suggest that higher levels of RSAB may mitigate the influence of environmental risk on the development of inhibitory control early childhood.

CognitiveTask

GiftWrap

10.1002/dev.21315

Developmental psychobiology

Dev Psychobiol

Associations between respiratory sinus arrhythmia (RSA) reactivity and effortful control in preschool-age children.

We tested whether respiratory sinus arrhythmia (RSA) reactivity in response to each of three self-regulation tasks (bird and dragon; knock-tap; and gift wrap) would predict self-regulation performance in a sample of 101 preschool-age children (M age = 4.49, SD = .64). While controlling for baseline RSA, decreases in RSA from bird and dragon to knock-tap (but not from baseline to bird and dragon) predicted a latent variable measuring self-regulation. Furthermore, increases in RSA from the knock-tap to gift wrap-the only task involving delay of gratification-were related to concurrent task performance while controlling for the relation between RSA reactivity and the latent self-regulation variable. Results suggest that the relations between RSA reactivity and self-regulatory ability are influenced by task-specific demands and possibly by task order. Furthermore, RSA reactivity appears to relate differently to performance on motivationally salient self-regulation tasks such as delay of gratification relative to cool executive function tasks.

CognitiveTask

GiftWrap

10.1111/jcpp.12230

Journal of child psychology and psychiatry, and allied disciplines

J Child Psychol Psychiatry

Inhibitory control and delay aversion in unaffected preschoolers with a positive family history of attention deficit hyperactivity disorder.

From current theories on the etiology of attention deficit hyperactivity disorder (ADHD), it can be inferred that delay aversion (DA) and deficits in inhibitory control (IC) constitute basic deficits or endophenotypes of the disorder that already occur in the preschool period. This implies an occurrence of the characteristics in unaffected preschoolers with a positive family history of ADHD. Thus, it is hypothesized that preschoolers who are not affected by ADHD but who have first-degree relatives who suffer, or have suffered, from ADHD show deficits in IC and heightened DA in comparison to preschoolers from the general population. Thirty unaffected preschoolers with a positive family history of ADHD were compared with 30 control children matched with respect to age in months, gender, intelligence, and maternal education level. The groups also did not differ in terms of maternal depressive symptoms and the number of psychosocial family risks. A set of age-appropriate neuropsychological tasks on executive IC (e.g. Puppet Says, Day-Night, relying on Go-NoGo and interference paradigms) and DA (e.g. Snack Delay, Gift Wrap, relying on delay of gratification paradigm) was conducted. Unaffected preschoolers showed significantly higher DA than control children (t(29) = -2.57, p < .008). The result did not change when subclinical ADHD symptoms and symptoms of oppositional defiant disorder were controlled for (F(1,29) = 5.21, p < .031). Differences in IC did not reach statistical significance. The results are compatible with the assumption that DA constitutes a familial vulnerability marker that can be validly assessed in the preschool period. As this is the first study to address this issue in preschoolers, more research is needed to confirm and further analyze the significance of DA assessments specifically at this developmental stage.

CognitiveTask

GiftWrap

10.1089/bfm.2011.0135

Breastfeeding medicine : the official journal of the Academy of Breastfeeding Medicine

Breastfeed Med

Prevalence of baby bottle versus breastfeeding graphics on products in national chain stores.

This study surveyed the prevalence of bottle versus breastfeeding graphic images on products marketed for pregnant mothers and young children available for purchase in national chain stores. This was a product survey/content analysis. Eighteen national chain stores located in a 10-mile radius of Charlottesville, VA were visited. In total, 2,670 individual items in 11 categories of baby shower and baby gift merchandise (shower invitations, greeting cards, gift wrap, shower decorations, baby dolls, baby books, infant clothing, bibs, nursery decorations, baby blankets, and disposable diapers) were assessed. The main outcome measures were prevalences of baby bottle and breastfeeding graphic images. Baby bottle images were found on products in eight of the 11 categories of items surveyed. Thirty-five percent of baby dolls were marketed with a baby bottle. The prevalence of bottle images on items in all other categories, however, was low. Of the 2,670 items surveyed, none contained a breastfeeding image. The low prevalence of baby bottle images on commonly purchased baby gift and baby shower items is encouraging. However, the absence of breastfeeding images and the relatively high prevalence of baby dolls marketed with a baby bottle demonstrate that breastfeeding is not portrayed as the physiologic norm on these products. Product designers should explore ways to promote breastfeeding, consumers should make informed choices in product selection, and advocacy groups should promote guidelines for these products.

CognitiveTask

GiftWrap

10.1002/imhj.20155

Infant mental health journal

Infant Ment Health J

With a little help from my friends?: Self-regulation in groups of young children.

This study examined self-regulation in preschool children (mean age=51 months; 47% boys) using three situational assessments tapping delay of gratification and motor control. Assessments represented a novel adaptation for use with both individual (N=116) and groups (N=44) of four familiar peers in ecologically valid settings. Results suggest that preschoolers demonstrate an increasing ability to self-regulate with age, as well as some evidence for girls performing better than boys on the Gift Wrap situational assessment. Children were less able to demonstrate self-regulation in the peer group context as compared to individual assessments. Differences between age groups and gender were not significant when children were assessed with their peers. The influence of peers on self-regulation behavior is a complex relationship with no clear patterns identified in this research. Implications for future research and assessment efforts are discussed.

CognitiveTask

GiftWrap

10.1016/j.jaapos.2007.02.009

Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus

J AAPOS

Traumatic globe luxation in a 6-year-old girl playing with a tube of wrapping paper.

A 6-year-old girl was playing by herself with a tube of gift wrap just before the winter holidays. In a panic, she came upstairs from the den with a protruding right eye. When used as a make-believe telescope, the tube of wrapping paper was the perfect diameter to fit within the orbit's bony limits and around the globe. A small force to the tip of the tube held up to the eye was sufficient to propel the eyelids backward while luxating the globe forward. Visual acuity in the eye deteriorated within 2 hours but the vision loss was reversed entirely with prompt reduction under general anesthesia. While not intended as such, the gift-wrap tube has long been a popular play instrument for children around the holidays. This case illustrates the risk of luxating an eye with a gift-wrap tube and the benefits of prompt reduction of a traumatically luxated globe with traumatic optic neuropathy.

CognitiveTask

GiftWrap

10.1007/s00426-021-01545-y

Psychological research

Psychol Res

The surprising role of stimulus modality in the dual-task introspective blind spot: a memory account.

Being able to accumulate accurate information about one's own performance is important in everyday contexts, and arguably particularly so in complex multitasking contexts. Thus, the observation of a glaring gap in participants' introspection regarding their own reaction time costs in a concurrent dual-task context is deserving of closer examination. This so-called introspective blind spot has been explained by a 'consciousness bottleneck' which states that while attention is occupied by one task, participants cannot consciously perceive another stimulus presented in that time. In the current study, a series of introspective Psychological Refractory Period (PRP) experiments were conducted to identify the determinants of an introspective blind spot; to our surprise, in half of the experiments participants appeared to be aware of their dual-task costs. A single trial analysis highlighted the sensory modality of the two stimuli within the trial as an important predictor of introspective accuracy, along with temporal gaps in the trial. The current findings call into question the claim that attention is required for conscious awareness. We propose a memory-based account of introspective processes in this context, whereby introspective accuracy is determined by the memory systems involved in encoding and rehearsing memory traces. This model of the conditions required to build up accurate representations of our performance may have far-reaching consequences for monitoring and introspection across a range of tasks.

CognitiveTask

PRP

10.3758/s13423-021-01967-0

Psychonomic bulletin & review

Psychon Bull Rev

Multitasking costs on metacognition in a triple-task paradigm.

Multitasking situations, such as using one's phone while driving, are increasingly common in everyday life. Experimental psychology has long documented the costs of multitasking on task performance; however, little is known of the effects it has on the metacognitive processes that monitor such performance. The present study is a step toward filling this void by combining psychophysical procedures with complex multitasking. We devised a multimodal paradigm in which participants performed a sensorimotor tracking task, a visual discrimination task, and an auditory 2-back working memory task, either separately or concurrently, while also evaluating their task performance every ~15 s. Our main finding is that multitasking decreased participants' awareness of their performance (metacognitive sensitivity) for all three tasks. Importantly, this result was independent of the multitasking cost on task performance, and could not be attributed to confidence leak, psychological refractory period, or recency effects on self-evaluations. We discuss the implications of this finding for both metacognition and multitasking research.

CognitiveTask

PRP

10.1037/xge0001020

Journal of experimental psychology. General

J Exp Psychol Gen

Testing the over-reliance on central attention (ORCA) hypothesis: Do older adults have difficulty automatizing especially easy tasks?

Does aging increase the reliance on central attention to carry out tasks, even when those tasks do not need it? To test the hypothesis of over-reliance on central attention (ORCA), we examined the ability of older adults to entirely bypass ideomotor-compatible (IM) tasks. IM tasks operate automatically for younger adults: The perception of an IM stimulus (e.g., a left-pointing arrow) directly activates the associated response code (e.g., pressing the left key). In a psychological refractory period (PRP) procedure, younger and older adults performed a auditory-vocal Task 1 paired with a visual-manual Task 2 that was either IM or non-IM. Task-2 compatibility (IM vs. non-IM) was manipulated as a between-subjects factor (Experiment 1) and as a within-subjects factor (Experiment 2). Both experiments yielded the counterintuitive finding of larger age differences in dual-task performance when Task 2 was easy (i.e., IM) than when it was difficult (i.e., non-IM), as evidenced by old/young ratio analyses and Brinley plots. Relatedly, whereas younger adults routinely bypassed the bottleneck with an IM Task 2 (as evidenced by a small PRP effect and a high rate of response reversals), older adults did not. The present findings cannot easily be explained by the hypotheses of generalized cognitive slowing and of specific processing deficits but support the ORCA hypothesis. As cognitive decline sets in, older adults begin to try harder: This extra application of central attention compensates for cognitive decline but can result in applying attention when it is not needed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

CognitiveTask

PRP

10.1016/j.concog.2020.103047

Consciousness and cognition

Conscious Cogn

The role of attentional slippage in Stroop dilution.

The present study examined the cognitive locus of Stroop dilution using a psychological refractory period (PRP) paradigm. Participants were asked to perform a tone discrimination task via a bimanual keypress response and a modified Stroop task via a vocal response serially as Task 1 and Task 2, respectively. In Task 2, a neutral word was added on half of the trials and no neutral word on the other half of the trials to observe the Stroop dilution effect. The amount of Stroop dilution, as well as the Stroop effect, was relatively constant across different stimulus-onset asynchronies (SOAs), which implies that Stroop dilution occurs due to the competition between a neutral word and a color word after a target color bar is selected to be processed further. These results indicate that focused attention plays an important role in the modulation of Stroop interference by the presence of a neutral word.

CognitiveTask

PRP

10.1016/j.actpsy.2020.103159

Acta psychologica

Acta Psychol (Amst)

Capacity limitations of processing presuppositions triggered by determiners.

Definite determiners trigger existence- and uniqueness-presuppositions, that is, the speaker assumes that it is taken for granted that there exists exactly one of the mentioned object in the relevant discourse. Indefinite determiners are associated with anti-uniqueness, that is, that there are several of the mentioned object. Applying the Maximize Presupposition principle, this additional meaning component arises as an anti-presupposition and involves first considering the definite determiner's uniqueness-presupposition and then its negation. We here investigate processing of the two determiners in more detail and ask whether this processing is automatic or requires limited central capacities. To do so, we employed the Psychological Refractory Period (PRP) approach and the locus of slack-logic. We observed more difficult processing for the indefinite compared to the definite determiner in felicitous sentences, and also in infelicitous compared to felicitous sentences. Further, immediate processing of the indefinite determiner appears capacity-limited. These results support the Maximize Presupposition principle and are an important step forward toward understanding cognitive processing of presuppositions.

CognitiveTask

PRP

10.2196/21659

JMIR research protocols

JMIR Res Protoc

Artificial Intelligence-Powered Smartphone App to Facilitate Medication Adherence: Protocol for a Human Factors Design Study.

Medication Guides consisting of crucial interactions and side effects are extensive and complex. Due to the exhaustive information, patients do not retain the necessary medication information, which can result in hospitalizations and medication nonadherence. A gap exists in understanding patients' cognition of managing complex medication information. However, advancements in technology and artificial intelligence (AI) allow us to understand patient cognitive processes to design an app to better provide important medication information to patients. Our objective is to improve the design of an innovative AI- and human factor-based interface that supports patients' medication information comprehension that could potentially improve medication adherence. This study has three aims. Aim 1 has three phases: (1) an observational study to understand patient perception of fear and biases regarding medication information, (2) an eye-tracking study to understand the attention locus for medication information, and (3) a psychological refractory period (PRP) paradigm study to understand functionalities. Observational data will be collected, such as audio and video recordings, gaze mapping, and time from PRP. A total of 50 patients, aged 18-65 years, who started at least one new medication, for which we developed visualization information, and who have a cognitive status of 34 during cognitive screening using the TICS-M test and health literacy level will be included in this aim of the study. In Aim 2, we will iteratively design and evaluate an AI-powered medication information visualization interface as a smartphone app with the knowledge gained from each component of Aim 1. The interface will be assessed through two usability surveys. A total of 300 patients, aged 18-65 years, with diabetes, cardiovascular diseases, or mental health disorders, will be recruited for the surveys. Data from the surveys will be analyzed through exploratory factor analysis. In Aim 3, in order to test the prototype, there will be a two-arm study design. This aim will include 900 patients, aged 18-65 years, with internet access, without any cognitive impairment, and with at least two medications. Patients will be sequentially randomized. Three surveys will be used to assess the primary outcome of medication information comprehension and the secondary outcome of medication adherence at 12 weeks. Preliminary data collection will be conducted in 2021, and results are expected to be published in 2022. This study will lead the future of AI-based, innovative, digital interface design and aid in improving medication comprehension, which may improve medication adherence. The results from this study will also open up future research opportunities in understanding how patients manage complex medication information and will inform the format and design for innovative, AI-powered digital interfaces for Medication Guides. PRR1-10.2196/21659.

CognitiveTask

PRP

10.5334/joc.121

Journal of cognition

J Cogn

S1-R2 and R1-R2 Backward Crosstalk Both Affect the Central Processing Stage.

A frequent observation in dual-task experiments is that performance in Task 1 is influenced by conceptual or spatial overlap with features of Task 2. Such compatibility-based backward crosstalk effects (BCEs) can occur when overlap exists between the responses of two tasks-the R1-R2 BCE-or between the stimulus in Task 1 and the response in Task 2-the S1-R2 BCE. The present study investigated whether the S1-R2 BCE has a perceptual locus, and by implication, whether the two BCEs have a common processing locus or different ones. To this end, we applied the additive factors logic and manipulated the duration of the Task 1 perceptual stage. The results argue against a perceptual locus for both BCEs. As a possible explanation, we suggest that the R1-R2 BCE and the S1-R2 BCE have their locus within a capacity-limited central stage, but that they arise from different processes within this stage. The R1-R2 BCE influences Task 1 response selection, whereas the S1-R2 BCE influences Task 1 stimulus classification. A plausible though post-hoc model is presented within the Discussion.

CognitiveTask

PRP

10.3758/s13414-020-02158-0

Attention, perception & psychophysics

Atten Percept Psychophys

Dual task interference on early perceptual processing.

When two tasks, Task 1 and Task 2, are conducted in close temporal proximity and a separate speeded response is required for each target (T1 and T2), T2 report performance decreases as a function of its temporal proximity to T1. This so-called psychological refractory period (PRP) effect on T2 processing is largely assumed to reflect interference from T1 response selection on T2 response selection. However, interference on early perceptual processing of T2 has been observed in a modified paradigm, which required changes in visual-spatial attention, sensory modality, task modality, and response modality across targets. The goal of the present study was to investigate the possibility of early perceptual interference by systematically and iteratively removing each of these possible non perceptual confounds, in a series of four experiments. To assess T2 visual memory consolidation success, T2 was presented for a varying duration and immediately masked. T2 report accuracy, which was taken as a measure of perceptual-encoding or consolidation-success, decreased across all experimental control conditions as T1-T2 onset proximity increased. We argue that our results, in light of previous studies, show that central processing of a first target, responsible for the classical PRP effect, also interferes with early perceptual processing of a second target. We end with a discussion of broader implications for psychological refractory period and attentional blink effects.

CognitiveTask

PRP

10.1177/1747021820943130

Quarterly journal of experimental psychology (2006)

Q J Exp Psychol (Hove)

Semantic interference is not modality specific: Evidence from sound naming with distractor pictures.

In three experiments, participants named environmental sounds (e.g., the bleating of a sheep by producing the word "sheep") in the presence of distractor pictures. In Experiment 1, we observed faster responses in sound naming with congruent pictures (e.g., sheep; congruency facilitation) and slower responses with semantically related pictures (e.g., donkey; semantic interference), each compared with unrelated pictures (e.g., violin). In Experiments 2 and 3, we replicated these effects and used a psychological refractory period approach (combining an arrow decision or letter rotation task as Task 1 with sound naming as Task 2) to investigate the locus of the effects. Congruency facilitation was underadditive with dual-task interference suggesting that it arises, in part, during pre-central processing stages in sound naming (i.e., sound identification). In contrast, semantic interference was additive with dual-task interference suggesting that it arises during central (or post-central) processing stages in sound naming (i.e., response selection or later processes). These results demonstrate the feasibility of sound naming tasks for chronometric investigations of word production. Furthermore, they highlight that semantic interference is not restricted to the use of target pictures and distractor words but can be observed with quite different target-distractor configurations. The experiments support the view that congruency facilitation and semantic interference reflect some general cognitive mechanism involved in word production. These results are discussed in the context of the debate about semantic-lexical selection mechanisms in word production.

CognitiveTask

PRP

10.1016/j.cognition.2020.104379

Cognition

Cognition

Automaticity of facial attractiveness perception and sex-specific mating strategies.

The current literature shows mixed results regarding whether the perception of facial attractiveness is automatic, i.e. that it operates independently from attentional resources. We argue that an evolutionary perspective on mating strategies provides a comprehensive account of the findings. In two studies, we used the locus-of-slack logic in a psychological refractory period paradigm. Task 1 was a speeded judgment of tone pitch (low vs. high), and Task 2 was a speeded judgment of whether a face was attractive or unattractive on two difficulty levels. Male and female participants judged the attractiveness of opposite-sex faces (Study 1, n = 73) or same-sex faces (Study 2, n = 94) in this paradigm. Results indicate that men do not need attentional resources when processing female faces (Study 1), but require attentional resources when processing same-sex faces (Study 2). In contrast, women need attentional resources to process the attractiveness of opposite as well as same-sex faces.

CognitiveTask

PRP

10.3758/s13414-020-02071-6

Attention, perception & psychophysics

Atten Percept Psychophys

Two sources of task prioritization: The interplay of effector-based and task order-based capacity allocation in the PRP paradigm.

When processing of two tasks overlaps, performance is known to suffer. In the well-established psychological refractory period (PRP) paradigm, tasks are triggered by two stimuli with a short temporal delay (stimulus onset asynchrony; SOA), thereby allowing control of the degree of task overlap. A decrease of the SOA reliably yields longer RTs of the task associated with the second stimulus (Task 2) while performance in the other task (Task 1) remains largely unaffected. This Task 2-specific SOA effect is usually interpreted in terms of central capacity limitations. Particularly, it has been assumed that response selection in Task 2 is delayed due to the allocation of less capacity until this process has been completed in Task 1. Recently, another important factor determining task prioritization has been proposed-namely, the particular effector systems associated with tasks. Here, we study both sources of task prioritization simultaneously by systematically combining three different effector systems (pairwise combinations of oculomotor, vocal, and manual responses) in the PRP paradigm. Specifically, we asked whether task order-based task prioritization (SOA effect) is modulated as a function of Task 2 effector system. The results indicate a modulation of SOA effects when the same (oculomotor) Task 1 is combined with a vocal versus a manual Task 2. This is incompatible with the assumption that SOA effects are solely determined by Task 1 response selection duration. Instead, they support the view that dual-task processing bottlenecks are resolved by establishing a capacity allocation scheme fed by multiple input factors, including attentional weights associated with particular effector systems.

CognitiveTask

PRP

10.1016/j.jecp.2020.104866

Journal of experimental child psychology

J Exp Child Psychol

Investigating dual-task interference in children versus young adults with the overlapping task paradigm.

Previous studies demonstrated that dual-task impairments (i.e., dual-task costs) are higher in children than in young adults. However, these studies did not specify the mechanisms explaining higher dual-task costs and did not assess the specific task processes that particularly impair simultaneous task performance in children. We assessed sources of higher dual-task costs in children (n = 32) as compared with young adults (n = 32) by combining auditory (Task 1) and visual (Task 2) sensorimotor tasks into dual tasks of the psychological refractory period (PRP) type. Both tasks are separated by a varying stimulus onset asynchrony (SOA). In Visual Task 2, we manipulated task difficulty at the perceptual stage (contrast manipulation) and response selection stage (mapping manipulation) in order to identify age-related changes in capacity limitations during dual-task performance. The results showed that the response selection manipulation and SOA yielded additive effects in children and young adults, providing evidence for interference at response selection processes in both age groups. In contrast, the perceptual stage manipulation and SOA resulted in underadditive effects in young adults and additive effects in children. This age-related difference is consistent with the assumption that limitations in central processing are present in both age groups, whereas perceptual interference between tasks seems to be larger in children than in young adults.

CognitiveTask

PRP

10.3758/s13414-020-02039-6

Attention, perception & psychophysics

Atten Percept Psychophys

Disentangling stimulus and response compatibility as potential sources of backward crosstalk.

In two experiments (N= 60 each), we investigated the locus of backward crosstalk effects in dual tasking. Specifically, we embedded the typical flanker task within a dual-task paradigm by assigning stimulus-response (S-R) rules to the flankers. In Experiment 1, participants were instructed to first respond to the center letter and only respond to the flanker if the center was a no-go stimulus (i.e., prioritized processing paradigm). Mapping condition was varied between-subjects to be either matched (i.e., same S-R rule for flankers as for center letters), reversed (i.e., opposite S-R rule for flankers), or neutral (i.e., different letters for flankers with separate S-R rules). The results indicated that the backward crosstalk effect was mainly driven by a stimulus-based compatibility, as indicated by a significant S-R compatibility effect in the matched and reversed conditions, with little change in this effect between the matched and reversed conditions. Experiment 2 replicated and extended these findings to a psychological refractory period paradigm. The present findings suggest that in the matched and reversed conditions, there was only one S-R rule active at a time.

CognitiveTask

PRP

10.1177/1747021820928030

Quarterly journal of experimental psychology (2006)

Q J Exp Psychol (Hove)

Dissociating central and auditory attention: Is there a shared bottleneck for response selection and auditory search?

Central and auditory attention are limited in capacity. In dual-tasks, central attention is required to select the appropriate response, but because central attention is limited in capacity, response selection can only be carried out for one task at a time. In auditory search tasks, search time to detect the target sound increases with the number of distractor sounds added to the auditory scene (set sizes), indicating that auditory attention is limited in capacity. Here, we investigated whether central and auditory attention relied on common or distinct capacity limitations using a dual-task paradigm. In two experiments, participants completed a visual choice discrimination task (task 1) together with an auditory search task (task 2), and the two tasks were separated by an experimentally modulated stimulus onset asynchrony (SOA). Analysing auditory search time as a function of SOA and set sizes (locus-of-slack method) revealed that the auditory search process in task 2 was performed after response selection in a visual two-choice discrimination task 1 (Experiment 1), but concurrently with response selection in a visual four-choice discrimination task 1 (Experiment 2). Hence, although response selection in the visual four-choice discrimination task demanded more central attention as compared with response selection in the two-choice discrimination task, the auditory search process was performed in parallel. Distribution analyses of inter-response time further indicated that parallel processing of response selection and auditory search was not influenced by response grouping. Taken together, the two experiments provided evidence that central and auditory attention relied on distinct capacity limitations.

CognitiveTask

PRP

10.3758/s13414-020-02036-9

Attention, perception & psychophysics

Atten Percept Psychophys

Feature binding contributions to effect monitoring.

Monitoring the perceptual effects of body movements is supposed to be a capacity-limited process that can interfere with processing of a concurrent task. Here we studied the contribution of feature binding to such effect monitoring interference. In three experiments, we varied the possibility of feature overlap between responses and effects in a primary task and responses in a secondary task. We show that responses in a secondary task are delayed when they partially, rather than completely, alternate or repeat features of responses/effects of a primary task. Yet, these partial feature repetition/alternation costs are small, and they occur on top of other factors that lengthen the critical effect monitoring process, such as the spatial compatibility of responses and effects in the primary task. The results thus show that feature binding contributes to, but cannot fully account for, delays in a secondary task caused by monitoring effects of a primary task.

CognitiveTask

PRP

10.1007/s00426-020-01337-w

Psychological research

Psychol Res

Parallel and serial task processing in the PRP paradigm: a drift-diffusion model approach.

Even after a long time of research on dual-tasking, the question whether the two tasks are always processed serially (response selection bottleneck models, RSB) or also in parallel (capacity-sharing models) is still going on. The first models postulate that the central processing stages of two tasks cannot overlap, producing a central processing bottleneck in Task 2. The second class of models posits that cognitive resources are shared between the central processing stages of two tasks, allowing for parallel processing. In a series of three experiments, we aimed at inducing parallel vs. serial processing by manipulating the relative frequency of short vs. long SOAs (Experiments 1 and 2) and including no-go trials in Task 2 (Experiment 3). Beyond the conventional response time (RT) analyses, we employed drift-diffusion model analyses to differentiate between parallel and serial processing. Even though our findings were rather consistent across the three experiments, they neither support unambiguously the assumptions derived from the RSB model nor those derived from capacity-sharing models. SOA frequency might lead to an adaptation to frequent time patterns. Overall, our diffusion model results and mean RTs seem to be better explained by participant's time expectancies.

CognitiveTask

PRP

10.3758/s13423-020-01735-6

Psychonomic bulletin & review

Psychon Bull Rev

Ideomotor compatibility enables automatic response selection.

A task is ideomotor (IM)-compatible when there is high conceptual similarity between the stimulus and the associated response (e.g., pressing a left key when an arrow points to the left). For such an easy task, can response selection operate automatically, bypassing the attentional bottleneck that normally constrains dual-task performance? To address this question, we manipulated the IM compatibility of a Task 2 that was performed concurrently with a non-IM-compatible Task 1, using the psychological refractory period procedure. Single-task trials, randomly intermixed with dual-task trials, served as a baseline against which to assess dual-task costs. The results indicated bottleneck bypassing (i.e., simultaneous response selection on both tasks) when Task 2 was IM-compatible, as evidenced by negligible dual-task costs on Task 2 (as well as on Task 1), very high percentages of response reversals, and weak correlations between Task-1 and Task-2 reaction times. These findings were supported by a fine-grained simulation analysis of inter-response intervals. We conclude that the perception of an IM-compatible stimulus directly activates the response code, which can then be selecting automatically, without recruiting central attention, consistent with A. G. Greenwald's (Journal of Experimental Psychology, 94, 52-57, 1972) original theory of IM compatibility.

CognitiveTask

PRP

10.1007/s00426-020-01318-z

Psychological research

Psychol Res

Item-specific proportion congruency (ISPC) modulates, but does not generate, the backward crosstalk effect.

When both tasks in a psychological refractory period (PRP) paradigm have compatible manual responses, a compatibility benefit in RT can often be observed on Task1 performance, in apparent violation of a strict traditional response selection bottleneck model. This compatibility-based backward crosstalk effect (BCE) has been generally attributed to automatic activation of Task2 response information, in parallel with attended Task1 performance. This paper tests a potential alternative mechanism of the BCE. Item-specific proportion congruency (ISPC) effects are previously well demonstrated, where learning of associations between stimuli and task conflict (e.g., that particular Stroop items are typically incongruent) allows rapidly and automatically elicited control adjustments in performance. Similar proportion manipulations have recently been shown to modulate the BCE in dual-task performance. If participants could similarly learn associations between particular pairs of stimuli and resulting response conflict in a PRP task, this kind of mechanism could produce relative speeding versus slowing of Task1 RT on response compatible versus incompatible trials. This pattern of data directly describes the BCE, and represents a potential alternative mechanism that does not require any response crosstalk, and would reinforce a stricter view of the response selection bottleneck model, if true. Over two experiments, we demonstrate that while the BCE is sensitive to ISPC-like effects based on Task1 conflict contingencies, the BCE is insensitive to relationships between particular pairs of stimuli and associated conflict. While ISPC effects can modulate the BCE, they do not generate the BCE. These findings reinforce the current Task2 parallel response activation account of the BCE.

CognitiveTask

PRP

10.3758/s13414-020-01978-4

Attention, perception & psychophysics

Atten Percept Psychophys

Cross-modal psychological refractory period in vision, audition, and haptics.

People's parallel-processing ability is limited, as demonstrated by the psychological refractory period (PRP) effect: The reaction time to the second stimulus (RT2) increases as the stimulus onset asynchrony (SOA) between two stimuli decreases. Most theoretical models of PRP are independent of modalities. Previous research on PRP mainly focused on vision and audition as input modalities; tactile stimuli have not been fully explored. Research using other paradigms and involving tactile stimuli, however, found that dual-task performance depended on input modalities. This study explored PRP with all the combinations of input modalities. Thirty participants judged the magnitude (small or large) of two stimuli presented in different modalities with an SOA of 75-1,200 ms. PRP effect was observed, i.e., RT2 increased with a decreasing SOA, in all the modalities. Only in the auditory-tactile condition did the accuracy of Task 2 decrease with a decreasing SOA. In the auditory-tactile and tactile-visual conditions, RT to the first stimulus also increased with a decreasing SOA. Current models could only explain part of the results, and modality characteristics help to explain the overall data pattern better. Limitations and directions for future studies regarding reaction time, task difficulty, and response modalities are discussed.

CognitiveTask

PRP

10.1007/s10936-019-09686-3

Journal of psycholinguistic research

J Psycholinguist Res

Is Immediate Processing of Presupposition Triggers Automatic or Capacity-Limited? A Combination of the PRP Approach with a Self-Paced Reading Task.

Informally speaking, presuppositions are meaning components which are part of the common ground for speakers in a conversation, that is, background information which is taken for granted by interlocutors. The current literature suggests an immediate processing of presuppositions, starting directly on the word triggering the presupposition. In the present paper, we focused on two presupposition triggers in German, the definite determiner the (German der) and the iterative particle again (German wieder). Experiment 1 replicates the immediate effects which were previously observed in a self-paced reading study. Experiment 2 then investigates whether this immediate processing of presuppositions is automatic or capacity-limited by employing the psychological refractory period approach and the locus of slack-logic, which have been successfully employed for this reason in various fields of cognitive psychology. The results argue against automatic processing, but rather suggest that the immediate processing of presuppositions is capacity-limited. This potentially helps specifying the nature of the involved processes; for example, a memory search for a potential referent.

CognitiveTask

PRP

10.1007/s00426-019-01261-8

Psychological research

Psychol Res

Electrophysiological examination of response-related interference while dual-tasking: is it motoric or attentional?

The possibility that interference between motor responses contributes to dual-task costs has long been neglected, yet is supported by several recent studies. There are two competing hypotheses regarding this response-related interference. The motor-bottleneck hypothesis asserts that the motor stage of Task 1 triggers a refractory period that delays the motor stage of Task 2. The response-monitoring hypothesis asserts that monitoring of the Task-1 motor response delays the response-selection stage of Task 2. Both hypotheses predict lengthening of Task-2 response time (RT2) when Task 1 requires motor processing relative to when it does not. However, they assume different loci for the response-related bottleneck, and therefore make different predictions regarding (a) the interaction between Task-1 motor requirement and the Task-2 difficulty effect as measured by RT2 and (b) the premotoric durations and motoric durations of Task 2 as measured by lateralized readiness potentials (LRPs). To test these predictions, we conducted two experiments manipulating the Task-1 motor requirement (Go vs. NoGo) and Task-2 response-selection difficulty, as well as the stimulus-onset asynchrony (SOA). Task-1 motor processing significantly lengthened RT2, suggesting response-related interference. Importantly, the Task-1 motor response reduced the Task-2 difficulty effect at the short SOA, indicating postponement of the Task-2 motor stage, consistent with the motor-bottleneck hypothesis. Further consistent with the motor-bottleneck hypothesis, the Task-2 LRP indicated a consistent premotoric duration of Task 2 regardless of Task-1 motor requirement. These results are difficult to reconcile with the response-monitoring hypotheses, which places the response-related bottleneck before the response-selection stage of Task 2. The results also have important implications regarding use of locus-of-slack logic in PRP studies.

CognitiveTask

PRP

10.1007/s00426-019-01282-3

Psychological research

Psychol Res

Introspection about backward crosstalk in dual-task performance.

The present study investigated participants' ability to introspect about the effect of between-task crosstalk in dual tasks. In two experiments, participants performed a compatibility-based backward crosstalk dual task, and additionally provided estimates of their RTs (introspective reaction times, IRTs) after each trial (Experiment 1) or after each pair of prime and test trials (Experiment 2). In both experiments, the objective performance showed the typical backward crosstalk effect and its sequential modulation depending on compatibility in the previous trial. Very similar patterns were observed in IRTs, despite the typical unawareness of the PRP effect. In sum, these results demonstrate the reliability of between-task crosstalk in dual tasks and that people's introspection about the temporal processing demands in this complex dual-task situation is intriguingly accurate and severely limited at the same time.

CognitiveTask

PRP

10.1007/s00221-019-05716-7

Experimental brain research

Exp Brain Res

Global-local processing and dispositional bias interact with emotion processing in the psychological refractory period paradigm.

The reciprocal link between scope of attention and emotional processing is an important aspect of the relationship between emotion and attention. Larger scope of attention or global processing has been linked to positive emotions and narrow scope of attention or local processing has been linked to negative emotions. The nature of this relationship in the context of central capacity limitations and individual differences in attentional processing has not been studied in detail so far. To investigate such a relationship, here we used the psychological refractory period (PRP) paradigm, in which we manipulated the stimulus onset asynchrony (SOA: 150 ms, 300 ms, 900 ms) of stimuli corresponding to two tasks in a sequence. The first task was identifying a number at the global or local level; the second task was recognizing the emotional expression (happy or angry). Additionally, predisposition towards local or global perceptual dimension was measured with the global-local task. Results indicated that global precedence modulated PRP effect and that response accuracy was impaired by the combination of local-angry task modalities. Interestingly, interference between simultaneous tasks was modulated by the predisposition to different perceptual levels resulting in different cognitive strategies for performing simultaneous tasks: locally biased subjects tended more towards serial processing, meanwhile globally biased ones were performing tasks in a parallel manner. This result suggest that individual differences may play a role in the choice of dual-task performing strategies.

CognitiveTask

PRP

10.3389/fnhum.2019.00391

Frontiers in human neuroscience

Front Hum Neurosci

Dual-Task Interference on Early and Late Stages of Facial Emotion Detection Is Revealed by Human Electrophysiology.

Rapid and accurate processing of potential social threats is paramount to social thriving, and provides a clear evolutionary advantage. Though automatic processing of facial expressions has been assumed for some time, some researchers now question the extent to which this is the case. Here, we provide electrophysiological data from a psychological refractory period (PRP) dual-task paradigm in which participants had to decide whether a target face exhibited a neutral or fearful expression, as overlap with a concurrent auditory tone categorization task was experimentally manipulated. Specifically, we focused on four event-related potentials (ERP) linked to emotional face processing, covering distinct processing stages and topography: the early posterior negativity (EPN), early frontal positivity (EFP), late positive potential (LPP), and also the face-sensitive N170. As expected, there was an emotion modulation of each ERP. Most importantly, there was a significant attenuation of this emotional response proportional to the degree of task overlap for each component, except the N170. In fact, when the central overlap was greatest, this emotion-specific amplitude was statistically null for the EFP and LPP, and only marginally different from zero for the EPN. N170 emotion modulation was, on the other hand, unaffected by central overlap. Thus, our results show that emotion-specific ERPs for three out of four processing stages-i.e., perceptual encoding (EPN), emotion detection (EFP), or content evaluation (LPP)-are attenuated and even eliminated by central resource scarcity. Models assuming automatic processing should be revised to account for these results.

CognitiveTask

PRP

10.1007/s00426-019-01272-5

Psychological research

Psychol Res

Dual-task interference and response strategies in simulated car driving: impact of first-task characteristics on the psychological refractory period effect.

Presentation of a task T1 typically delays the response to a subsequent task T2, more so with high temporal task overlap than with low temporal overlap. This so-called "psychological refractory period effect" (PRP effect) has been observed even if T1 required not a choice between distinct stimulus-response pairs, but rather between a given stimulus-response pair occurring once or twice. We explored which response strategy participants use for responding to such an unusual type of T1 and how such a T1 interacts with T2 performance. In a driving simulator, participants followed a lead car and had to honk when that car's rear window changed color (T1). In condition "pure", the color always changed once and required a single honk; in condition "mixed", the color changed once and required a single honk on some trials, but on other trials, it changed twice 200 ms apart and required a double honk. Participants also had to brake when the lead car braked (T2). On dual-task trials, T1 preceded T2 with a varying stimulus onset asynchrony (SOA) of 50-1200 ms. Reaction time to the first T1 stimulus was similar in "pure" and "mixed" and it was comparable with the reaction time to the second T1 stimulus. Reaction time to the T2 stimulus increased as SOA decreased from 350 to 50 ms, confirming the existence of a PRP effect. Furthermore, reaction time to the T2 stimulus was similar in "pure" and in "mixed" with one T1 stimulus, but was higher in "mixed" with two T1 stimuli. This pattern of findings is compatible with the view that presentation of the first T1 stimulus triggers a single response, which is amended into a double response, if a second T1 stimulus is displayed. The amendment does not need to wait until central processing of the original response is completed, and it therefore begins with no delay beyond the regular reaction time. Our findings further suggest that the mere possibility of a second T1 stimulus being presented does not increase the PRP effect on T2, probably because response amendments are not equivalent to classical response choices. However, the actual presentation of a second T1 stimulus indeed does increase the PRP effect on T2, probably because amendments start 200 ms later than the original response, and therefore prolong central processing of T1.

CognitiveTask

PRP

10.1016/j.neulet.2019.134531

Neuroscience letters

Neurosci Lett

An increase in the deoxygenated hemoglobin concentration induced by a working memory task during the refractory period in the hemodynamic response in the human cerebral cortex.

In activated brain regions, the deoxygenated hemoglobin (deoxy-Hb) concentration decreases despite an increase in oxygen consumption. This is attributed to the fact that the cerebral blood flow (CBF) induced by neuronal activation exceeds the accompanying increase in the cerebral metabolic rate of oxygen (CMRO). The discrepancy between large CBF and disproportionately small CMRO responses provides the basis for detecting the hemodynamic correlates of neuronal activities by functional magnetic resonance imaging (fMRI). However, this implies that if the supply of oxygen is made smaller than the oxygen consumed by the suppression of stimulus-induced CBF, the polarity of signals would be reversed. We used near-infrared spectroscopy (NIRS) to search for a condition wherein a marked decrease in the stimulus-evoked oxygenated Hb (oxy-Hb) concentration change was accompanied by an increase in the deoxy-Hb concentration in the human brain. We found that when a specific brain region was activated by two working memory (WM) task blocks in rapid succession, the local change in the deoxy-Hb concentration evoked by the second task block was reversed to an increase due to the refractory effect in the hemodynamic response. The result suggests that the polarity of the blood oxygenation level-dependent (BOLD) signal could change during repetitive neuronal activation, and thus caution must be taken in the interpretation of the BOLD signal under such situations.

CognitiveTask

PRP