The impacts of perceptual load and driving duration on mind wandering in driving

•The study examined the effects of perceptual load and driving duration.•Response variables included the rate of mind wandering and cost on vehicular control.•Generalized additive mixed effects models were used.•Under a higher perceptual load, participants’ mind wandered less often.•Driving performance fluctuated greatly over the driving duration when mind wandering. A significant portion of the risk of driver distraction comes from the cognitive consequences of attention deviating from the current task. While distraction can be due to external stimulations such as flashing billboards or a ringing phone, simply engaging in internally-generated task-unrelated thoughts (i.e., mind wandering) could raise one’s crash risk as well. Compared to the extensive efforts in recent years to understand the mechanisms of external distraction, relatively little is known about internal distraction such as mind wandering. This study investigated how perceptual load and driving duration can impact both the rate of mind wandering and its costs on drivers’ performance in vehicular control. Generalized additive mixed effects models were used to estimate these effects in both a lower perceptual load scenario and a higher perceptual load scenario in simulated driving. Our study found that, under a higher perceptual load, participants’ minds wandered less often. Significant nonlinear effects for driving duration were found on vehicular control during mind wandering for both perceptual load conditions, while the effect of driving duration was linear for on-task periods. These results suggest that, while mind wandering, individuals’ driving performance fluctuates greatly, which has significant implications on driving safety for individual drivers and overall traffic flow.