Abstract
It has been shown that in locomotor tasks people actively direct their gaze to locations in an environment at the right time so as to support locomotor control (Land, et al., 1994; Wilkie, et al., 2008). When walking to intercept a moving target, people appear to maintain the target at a constant bearing angle with respect to an allocentric reference axis (Chardenon, et al., 2002; Fajen, et al., 2004, 2007; Lenoir, et al., 1999). Therefore the question arises how humans direct their gaze during steering for interception. To examine it, participants (N=18) drove a car to intercept a moving target in a virtual environment. The environment was presented stereoscopically in a head mounted display. While the car moved at a constant speed (7 m/s), participants controlled its moving direction using a steering wheel. The target (40m distant) moved to the left or right at a constant speed (4, 5, or 6 m/s) in a trial. In half the trials, the target remained visible through a trial; in the other half, it suddenly disappeared 2.5 s after it appeared. When intercepting the visible target, participants initially made saccades to the target, and then smoothly pursued it until interception. The bearing angle towards the target systematically changed during interception. Instead, participants appeared to maintain the target at a constant angle with respect to the direction of the car's current heading, with increasing variability as they approached the target. Interception accuracy with visible target was significantly higher than that with invisible target (p< 0.01). After the target disappeared in a trial, participants usually directed their gaze in the direction of the car's heading, which was accompanied by a lack of effective steering adjustment. The results are indicative of the active role of eye movement in locomotor interception and the adaptiveness of locomotor control.
Meeting abstract presented at VSS 2016