Daichi KIMURA

Analysis of the Impact of Secondary Tasks during Congested Driving on the Prevention of Vigilance Decrement

Kazushi SANO

The purpose of this study was to analyze the effects of secondary tasks on arousal and vigilance decrement during driving in traffic congestion, and to present measures to reduce distracted driving from the results. First, a preliminary experiment was conducted to investigate the effect of interest in the secondary task on arousal level in providing the secondary task. As a result, there was no difference in arousal level depending on the degree of interest in the secondary task. Next, to investigate the effects of the secondary task on the decrease in vigilance and arousal level, we conducted an experiment assuming driving in a traffic congestion, measured biological responses, and analyzed them. Reaction time was used as an index of decreased vigilance, and visual behavior and pupil diameter change were used as indices of arousal. Two types of data were analyzed: one from a previous study and the other from this study. The secondary tasks were passive and active, based on the assumption that the attitude toward the task affects arousal level. In this experiment, the secondary task was changed during the course of the experiment, and its effects were investigated. The results of the analysis showed a decrease in arousal level during the passive secondary task, while an effect of maintaining arousal level was observed during the active secondary task. However, when a single secondary task was performed, a decrease in vigilance occurred regardless of the type of secondary task. On the other hand, when the secondary task was changed in the middle of a task, the participants showed a higher arousal level than when a single secondary task was performed, and no decrease in vigilance was observed, indicating that changing the secondary task had an effect on the arousal level. This study indicates that appropriate provision of secondary tasks may prevent the decline in vigilance when driving in traffic congestion.