Comparing Accounts of Psychomotor Vigilance Impairment Due to Sleep Loss

The effects of fatigue on cognitive processing are not fully understood. Computational modeling research has led to two distinct accounts of fatigue, and specifically its effects on psychomotor vigilance performance, which are both supported by empirical findings. The first account is based on ACT-R and posits that fatigue increases the probability of microlapses. A biomathmatical model of fatigue modulates this probability. The second account is based on a diffusion model and posits that fatigue decreases the drift rate of the diffusion process. The same biomathematical model of fatigue is used to control the drift rate parameter. We compare the models’ predicted reaction time distributions to one another and to human data in a psychomotor vigilance performance task. Though they embody entirely different modeling approaches and different levels of abstraction, the accounts generate equivalent predictions and capture the detrimental effects of fatigue through mechanisms that have similar theoretical interpretations. In both accounts, fatigue effectively increases the contribution of noise to cognitive processing and decreases neural inhibition. This unexpected convergence supports a more general account of how sleep deprivation impairs psychomotor vigilance performance through degradation of the quality of cognitive processing.