Comparison of Performance and Physiological Changes Between Drivers who Perform Well and Poorly During Prolonged Vehicular Operation

This study consisted of separate experiments conducted on three different California State Highways. It had the purpose of discriminating performance and physiological differences between groups of drivers who operated a specially instrumented vehicle well or poorly under prolonged, monotonous night driving conditions. The vigilance of the better and poorer groups of drivers, defined by the frequency of inadvertent drifting from the assigned traffic lane, deteriorated to different degrees. Self-assessments of alertness and fatigue were related to driving performance of the better and poorer groups on the same highway but not between different highways. Better and poorer groups of drivers differed with respect to mean heart rate, heart rate variability, and power within the alpha, theta, and delta electroencephalogram (EEG) frequency bands. The types and degrees of physiological differences were strongly dependent upon the driver sample and highway circuit. Finally, unequivocal EEG signs of transient sleep were found in a few drivers showing extreme behavioral signs of fatigue and low vigilance.