Functional Equivalence of Sleep Loss and Time on Task Effects in Sustained Attention

Abstract

Research on sleep loss and vigilance both focus on declines in cognitive performance, but theoretical accounts have developed largely in parallel in these two areas. In addition, computational instantiations of theoretical accounts are rare. The current work uses computational modeling to explore whether the same mechanisms can account for the effects of both sleep loss and time on task on performance. A classic task used in the sleep deprivation literature, the Psychomotor Vigilance Test (PVT), was extended from the typical 10-min duration to 35 min, to make the task similar in duration to traditional vigilance tasks. A computational cognitive model demonstrated that the effects of time on task in the PVT were equivalent to those observed with sleep loss. Subsequently, the same mechanisms were applied to a more traditional vigilance task-the Mackworth Clock Task-providing a good fit to existing data. This supports the hypothesis that these different types of fatigue may produce functionally equivalent declines in performance.

No Evidence That Sleep Deprivation Effects and the Vigilance Decrement Are Functionally Equivalent: Comment on Veksler and Gunzelmann (2017)

“…In the vigilance model, the contingency between system cycles seems to be vestigial, perhaps reflecting the low rate of lapses in the authors' vigilance data (also recorded using the PVT, though in longer sessions). At the peak of the vigilance decrement, lapses were only about half as frequent as after a single night of sleep deprivation (5.23% vs. 9.03% of trials; Veksler & Gunzelmann, 2017). The lapse rate under vigilance conditions may even be beside the point, as we have no evidence that behavioral lapses during rested performance reflect anything like the physiological brain states associated with lapses after sleep deprivation.…”

“…And yet, Veksler and Gunzelmann's claim implies, for example, that we can learn how people perform when they are sleep deprived by studying how they perform when they are not. Veksler and Gunzelmann (2017) rest their case on a modeling exercise. They adapt a model previously developed to account for sleep deprivation effects (Gunzelmann, Gross, Gluck, & Dinges, 2009) to account for the vigilance decrement.…”

“…Another problem is that Veksler and Gunzelmann's (2017) modeling exercise actually suggests that sleep deprivation effects and the vigilance decrement are functionally distinct, just as the behavioral effects simulated by the two models are completely dissimilar. The sleep deprivation model of Gunzelmann et al (2009) simulates lapses, defined behaviorally as trials in a simple detection task (the Psychomotor Vigilance Task, or PVT) on which RT is greater than 500 ms. (These long RTs are taken to reflect a failure to timely detect the stimulus.)…”

“…Plots of a gamma distribution matching the data in fig. 4 of Veksler and Gunzelmann (2017). Each curve represents the response time distribution from a block of performance on the Psychomotor Vigilance Task.…”

“…The garnishes here suggest that sleep deprivation effects and the vigilance decrement are functionally distinct. Veksler and Gunzelmann (2017) propose that performing a vigilance task for 35 min has the same effect on the brain as sleep deprivation. This is an extraordinary claim that requires extraordinary evidence, yet what evidence there is contradicts the claim.…”