In this study, we focused on the possibility of improving driving performance as well as reducing mental fatigue and perceived time of drivers by providing appropriate secondary tasks to drivers in traffic congestion. The purpose is to clarify the effect of performing secondary tasks other than driving operations. Specifically, we conducted an experiment in which four types of secondary tasks were imposed over 15-minute periods in an indoor experimental environment that imitated driving operations in traffic congestion, and attempted to measure the effects by reaction delay time and multifaceted psychological indicators. As a result, while the secondary tasks do not make a clear difference in attention level, we found that the passive secondary tasks may increase the perceived time, and that the active secondary tasks may decrease it. In addition, the analysis of gender difference revealed that the active secondary task of "conversation" may have the effect of reducing stress and fatigue in males while increasing stress and fatigue in females.
