Psychomotor Vigilance Task

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

IV. Psychomotor Vigilance Task (PVT) as a Neurocognitive Assay for Sleep Loss... 

Psychomotor vigilance task performance is exquisitely sensitive to lapses as classically defined by Bills (39), Warren and Clarke (37), Bjemer (41), and Williams et al. (43). Figure 1 displays consecutive individual reaction times during a 10-min PVT task from a single subject at 12, 36, 60, and 84 hr of wakefulness during an 88-hr total sleep deprivation protocol (44). After 12 hr of wakefulness, responses were maintained at a fast and consistent level. In contrast, much longer responses become evident in PVT trials undertaken as time awake increased. The lapses (conventionally defined at RT > 500 msec) demonstrated not only... 

Psychomotor vigilance task performance has also been shown to be sensitive to reduced behavioral alertness associated with obstructive sleep apnea syndrome (OSAS), and the efficacy of interventions for OSAS. Performance of patients with OSAS is impaired on tasks that rely on the ability to sustain attention (85,86). As a measure of behavioral alertness, PVT performance has been demonstrated to be a sensitive method for assessing the attentional capability of patients with OSAS (32,87,88). Kribbs and colleagues (89) found that PVT performance and sleepiness, measured by the MSLT, both reflected the benefits of CPAP use (reduction in respiratory events during sleep). Similarly, the PVT has been used to demonstrate the positive effects of modafinil (a wake-promoting compound) on the capacity to sustain attention in a group of OSAS patients (34). 

Accurate assessment of neurobehavioral performance capability during sleep deprivation protocols requires cognitive performance assays to be (a) indicative of a fundamental aspect of waking cognitive function (b) easily performed (c) minimally affected by aptitude and learning (d) as brief as possible (e) valid and reliable (f) sensitive and (g) able to provide meaningful outcome variables that can be easily interpreted. In this chapter we have reviewed the evidence that the psychomotor vigilance task meets these requirements. 

Caldwell JA, Prazinko B, Caldwell JL. Body posture affects electronencephalo-graphic activity and psychomotor vigilance task performance in sleep-deprived subjects. Clin Neurophysiol 2003 114(1) 23—31. 

Graw P, Krauchi K, Knoblauch V, et al. Circadian and wake-dependent modulation of fastest and slowest reaction times during the psychomotor vigilance task. Physiol and Behav 2004 80(5) 695-701. 

The MSLT has been performed in patients with UARS, and abnormal results have been reported, but the test is often borderline normal, equating well with the complaint of fatigue. No systematic study of cognitive function has been performed in UARS patients, and investigation of mental lapses using tests such as the psychomotor vigilance task (PVT), a reaction-time test, is also lacking. But reevaluation of subjects treated with nasal CPAP demonstrated that sleep efficiency and MSLT scores improve (28). 

Lamond, N., Dawson, D. and Roach, G.D. (2005), Fatigue Assessment in the Field Validation of a Hand-Held Electronic Psychomotor Vigilance Task, Aviation Space and Environmental Medicine, 4, 486-489. 

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