Author(s): Walker, Trick
Mind-wandering is a mental state in which a person's attention is diverted away from a main task and towards more personal thoughts and goals. Nearly 85% of drivers have reported doing mind-wandering when driving, and performance decrements associated with mind-wandering typically include reduced visual scanning, poor speed, steering, and headway control, and increased risk of collision. But not all mind-wandering is equal. It can occur deliberately, like when a person chooses to plan their dinner during a routine commute home. Or it may occur accidentally and without awareness—many drivers have had the experience of "coming to" in their driveway with little memory of the interceding drive. What is unclear is whether these types of mind-wandering differ in the impact they have on driving performance.
In this study we examined whether rates of accidental versus deliberate mind-wandering differed depending on the demands of a drive, and how this subsequently affects driving performance. Specifically, we examined mind-wandering and driving performance in drives with low and high visual demand. We anticipated that more mind-wandering would occur during the low-demand drive, and that individuals would also be more likely to intentionally mind-wander when demands were low (as compared to high).
This study utilized a fixed-based Oktal simulator (a full car body surrounded by 300 degrees of screens). Participants completed two 30-minute highway drives, with visual demand manipulated by varying the amount of ambient traffic present—10 vehicles in the low-demand drive and 60 in the high-demand drive. Mind-wandering was measured using a probe method and two dash-mounted buttons were used to collect 'Accidental' and 'Deliberate' mind-wandering responses (no response required if not mind-wandering). Driving speed, steering performance, headway distance, and response times to hazard vehicles were also measured.
Although marginally more mind-wandering was reported during the low-demand drive than during the high-demand drive, participants driving performance was worse during the high-demand drive (e.g., more speeding, more variable steering, shorter following distance). Interestingly, regardless of drive demands, participants reported more accidental mind-wandering than deliberate mind-wandering.
Though less likely to occur, accidental mind-wandering that occurs under demanding conditions may actually be comparatively more detrimental to driving performance than mind-wandering that occurs under lower demand. Unlike deliberate mind-wandering, which can be stopped when a driver recognizes increasing demands, mind-wandering that occurs accidentally and without restriction places more strain on the already limited cognitive resources needed to monitor performance and drive safely under demanding driving conditions, leaving drivers ill-prepared to respond to further road events—if they notice them at all. Subsequent research aims to further evaluate how deeply the environment is processed by drivers when engaged in accidental versus deliberate mind-wandering.
Many drivers experience mind-wandering when driving. By manipulating driving demands, we demonstrated that although less mind-wandering may occur under difficult driving conditions, any accidental mind-wandering that does occur may be comparatively more costly to performance. This suggests that any intervention developed to reduce mind-wandering would be especially beneficial in situations where heightened attention is already important.