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Decreased Arousal as a Result of Sleep Deprivation: The Unraveling of Cognitive Control

Abstract : This chapter discusses recent efforts at developing mechanisms for capturing the effects of fatigue on human performance. We describe a computational cognitive model developed in ACT-R, that performs a sustained attentional task called the psychomotor vigilance (PVT). We use neurobehavioral evidence from research on sleep deprivation, in addition to previous research from within the ACT-R community, to select and to evaluate a mechanism for producing fatigue effects in the model. Fatigue is represented by decrementing a parameter associated with arousal in ACT-R, while also reducing a threshold value in the architecture to capture attempts at compensating for the negative effects of decreased arousal. These parameters are associated with the production utility computation in ACT-R, which controls the selection/execution cycle to determine which production (if any) to execute on each cognitive cycle. In ACT-R, this mechanism is linked to the basal ganglia and the thalamus. In turn, portions of the thalamus show heightened activation in attentional tasks under conditions of sleep deprivation. The model we describe closely captures the performance of human participants on the PVT, as observed in a laboratory experiment involving 88 hours of total sleep deprivation.