This preliminary study investigated objective measures for assessing safe driving ability in individuals with brain injury by combining driving-simulator performance with eye-movement tracking.
Participants were classified into mild and severe brain-injury groups based on Trail Making Test-B performance and the presence of visual-field defects, unilateral spatial neglect, or aphasia, and were compared with healthy controls. Driving performance was assessed using steering-angle variability on straight roads and speed variability on curved roads. Eye movements were recorded during hazard-detection and dangerous-driving situations, with particular attention to saccade frequency and amplitude.
The brain-injury groups showed greater variability in steering control or driving speed than the healthy group. More importantly, saccade amplitude during hazard-detection scenes was significantly smaller in both the mild and severe brain-injury groups, suggesting a narrower range of visual exploration.
The findings indicate that driving-simulator measures alone may not adequately evaluate both mild and severe brain injury. Saccade amplitude may therefore serve as a promising objective indicator of driving-related visual exploration and may complement conventional driving-simulator and neuropsychological assessments in clinical fitness-to-drive evaluations.
