Characteristics of Eye Movements and Correlation to Cognitive Functions in Relation to the Location of Guide Signs and Driving Speed.

Driving safety critically depends on the ability of drivers to efficiently recognize and process guide sign information under varying traffic conditions. This study examined how driving speed (slow/fast) and guide sign location (front/left) influence eye-movement behavior during guide sign recognition, and how these effects relate to drivers' cognitive functions and basic demographics. Twenty-four licensed drivers performed a guide sign recognition task using onboard video stimuli, and eye movements based on fixations and saccades were recorded. Generalized linear mixed models with participants as random effects were used to analyze the interactions between driving conditions, cognitive functions, demographics, and eye movement measures. Under low-load conditions, such as slow driving and front-positioned signs, individual differences in cognitive functions, including verbal memory and useful field of view, were strongly reflected in eye-movement behavior. Under high-load conditions characterized by fast driving and left-positioned signs, the influence of cognitive function was reduced, and eye movements were more strongly associated with driving experience. Increasing driving speed was associated with fewer eye movements, whereas the saccade amplitude remained unchanged, indicating the suppression of exploratory eye movements. For left-positioned signs, the fixation duration on the target was maintained, whereas gaze shifts between the forward environment and the sign were reduced.