ABSTRACT: This paper examines the degree to which time of day and levels of workload affect drivers' physiological arousal levels and driving behaviors. Drawing on data collected from 121 young adults in a driving simulation study, the results show that increased cognitive demand affects physiology and driving as well as suggesting that time of day exerts an influence. Participants who took part in the study in the late afternoon showed lower performance on a secondary cognitive task and higher levels of heart rate and skin conductance that are suggestive of greater challenge in managing overall demands. This increased workload, indicated by a spike in their levels of physiological arousal and lower task performance, suggests that participants had less available capacity at this point in the circadian cycle. These findings are consistent with reports of poorer driving performance and higher accident risk that have been observed in other studies during this time period. The results of this study underscore the need to account for time of day effects in research on driving behavior. Additionally, the findings on the pattern of responses across time periods have significance for the development of future in-vehicle workload management devices or safety systems that use physiological state measures as inputs.
Co-authors on the paper were Bryan Reimer, Lisa D'Ambrosio, Alexander Pina and Joseph Coughlin