Details of Research Outputs

Daily locomotion tasks such as walking and driving often occur in a complex environment in which people frequently need to divide their attention to keep track of multiple moving objects. In this study, we examined the effects of divided attention on the visual control of goal-oriented locomotion by using a dual-task paradigm in which participants were instructed to steer a virtual vehicle toward a target while dividing their attention to a concurrent object tracking task. We found that divided attention reduced the accuracy of the early-stage control of steering and the precision of the steady-state control. We then instructed participants to rely on the target egocentric direction or optic flow cue for steering. Although we found similar negative effects of divided attention on the control of steering regardless of the cue instructions, divided attention adversely affected the accuracy of the steady-state control of steering only for participants who were instructed to rely on the optic flow cue. Furthermore, participants consistently showed lower attentional tracking accuracy when steering at a fast (15 m/s) than a low (2 m/s) speed. We conclude that divided attention negatively affects the control of steering toward a goal, and steering at higher travel speeds demands more attentional resource. Compared with optic flow, relying on target egocentric direction to steer toward a goal is less affected by a concurrent attention-demanding task, suggesting that target egocentric direction is the primary cue for the control of goal-oriented locomotion.

Public Significance Statement Driver attention during locomotion is an important safety issue that concerns general public and car manufacturers. This study addressed a long-standing question of how divided attention affects the control of steering toward a goal at different travel speeds. The results show that the increase in attentional load negatively affects both the early-stage and the steady-state control of steering toward a goal. With the increase in travel speed, observers become more accurate and efficient with using optic flow for steering regardless of attentional load. Compared with optic flow, the control of steering toward a goal relying on target egocentric direction is less affected by a concurrent attention-demanding task.