Maintaining task set under fatigue: a study of time-on-task effects in simulated driving

An experiment was carried out in a driving simulator in order to study time-on-task effects in driving with special attention to distance keeping and hazard avoidance performance. As expected, increases of fatigue in the course of sustained performance were associated with a deterioration of perceptual-motor performance and an increase of safety margins. In general, the results indicate that performance in less central task components such as steering deteriorates in the course of time, whereas performance in high-priority sub-tasks such as hazard avoidance remains intact. Time-schedule instructions disrupted the adaptation of safety margins in prolonged driving. This study has practical implications for the design of driver impairment monitoring systems.