Decrements in performance in vigilance tasks are discussed in terms of habituation of the neutral responses to the background events of the tasks. Habituation of the arousal response leads to an increase in variance and amplitude of the spontaneous rhythms; this increase in neural noise may result in a decrease in sensitivity to the signal events. Habituation of the evoked responses to both signal and non-signal events of the task produces a decrease in amplitude and increase in latency of the evoked response. This may be cause of the decreases in correct and false detections which are found in many vigilance tasks. Sensitivity may increase as the neural evoked response to the nonsignal events decreases, thus counteracting the effect of the decrease in the arousal response.
Abstract