Effects of steering demand on lane keeping behaviour, self-reports, and physiology. A simulator study

▶ There is a threshold effect of steering demand on effort ratings. ▶ Psychophysiology was affected by high oncoming traffic density but not lane width. ▶ Decreased lateral variation is found as a result of increased steering demands. ▶ To assess driver workload multiple sources are required. ▶ Workload assessment is envisioned as predictor of inadequate performance in ADAS. In this study a driving simulator was used to determine changes in mental effort in response to manipulations of steering demand. Changes in mental effort were assessed by using subjective effort ratings, physiology, and the standard deviation of the lateral position. Steering demand was increased by exposure to narrow lane widths and high density oncoming traffic while speed was fixed in all conditions to prevent a compensatory reaction. Results indicated that both steering demand factors influence mental effort expenditure and using multiple measures contributes to effort assessment. Application of these outcomes for adaptive automation is envisaged.