The Effects of Mental Fatigue on Decision-Making for Collision Avoidance

Mental fatigue is a psychobiological state brought on by long periods of demanding cognitive activity and can impact cognitive performance. The aim of this study was to determine whether mental fatigue affects decision-making performance (response time and accuracy) during a collision avoidance task. Twenty-six young adults ( x̄ = 20.6 years ± 1.2) were randomly assigned to either a mental fatigue or a control group. In a virtual environment, participants approached a 90 cm doorway while a virtual person approached from the opposite side. As participants reached two meters from the doorway, the screen went blank, and they were instructed to respond as quickly and accurately as possible whether they would pass through the doorway first. The virtual person approached at four different speeds relative to the participant’s average walking speed (i.e. 0.8x, 0.9x, 1.1x, and 1.2x). After completing 20 trials, the mental fatigue group completed a 30-minute Stroop task while the control group watched a 30-minute documentary, followed by another block of the crossing order task. A 5-minute psychomotor vigilance task (PVT) was used as a behavioural measure of mental fatigue. Statistical analyses revealed a significant time by group interaction for PVT performance, such that the mental fatigue group demonstrated slower response times following the Stroop task. However, both groups demonstrated significantly faster response times and improved accuracy during the crossing order task following their respective intervention. The findings of this study suggest that the task was not cognitively demanding enough to reveal performance impairments associated with mental fatigue.