Lane keeping under cognitive distractions: performance and mechanisms

Cognitive distractions while driving often reduce the variability of lane position. However, data do not make clear whether smaller lane variability should be interpreted as a performance loss, indicating rigidified or unresponsive steering response to external stimuli, or a performance improvement in lane-keeping, indicating better lateral control. Four hypotheses, rigidified steering, visual enhancement, lateral prioritization, and automatic steering, debated on the performance implications and mechanisms of smaller lane variability under cognitive distractions. This dissertation project compares these hypotheses, and explores two important questions: first, whether the smaller lane variability under cognitive distraction indicates a performance loss or a performance gain in lane-keeping; second, what is the underlying cognitive mechanisms of lane variability reduction. Three studies have been carried out to assess drivers’ responsiveness to heavy lateral winds under varying levels of cognitive load. Data showed that cognitive load reduced the variability of lane position but increased the variability of vehicle speed, engendering more frequent steering activity but less frequent speed manipulation. Cognitive load also increased the coherence, or coupling between steering wheel position and lateral wind strength. More interestingly, distracted drivers produced quicker steering response time to the sudden onset of lateral wind. Results thus suggest that smaller lane variability under cognitive distractions is an indicator of better lane-keeping performance, and distracted drivers achieved better lane-keeping performance by actively prioritizing lateral control. Findings carry practical applications for mitigating driving risks and theoretical implications on the relationship between attention allocation and driving performance