Effects of non-driving-related-task modality and road geometry on eye movements, lane-keeping performance, and workload while driving

Abstract

Driving on horizontal, curved roads requires much research attention because it tends to result in more accidents compared to driving on straight roads. Several studies have found that non-driving-related-task (or secondary-task) sensory modality and horizontal-road geometry (e.g., curvature radius and curve direction) are major factors that affect driving performance and safety on horizontal curves. However, few studies have examined the combined effects of these factors. This paper reports a driving simulation study of the impacts of non-driving-related-task modality (4 levels), road curvature radius (4 levels), and curve direction (2 levels) on driver behaviour. Eye movements, lane-keeping performance, and subjective workload of 24 participants were measured. The results showed that drivers performing non-driving-related tasks using visual stimuli or manual responses on curved roads fixated less frequently and with shorter durations on the road and showed poorer lane-keeping performance compared to other modalities. In addition, when driving on sharper curves with a non-driving-related task, drivers looked at the road more frequently and longer, but their lane-keeping performance was poorer (i.e., higher standard deviations of lane position and of steering wheel angle). Participants reported higher visual demand when performing visual-speech types of tasks compared to auditory-manual types of tasks. The practical implications for driving safety on horizontal, curved roads are discussed.