Behaviour and gaze analyses during a goal-directed locomotor task.

The objectives of the current study were: (a) to determine whether perception-action coupling controlled behaviours when walking through moving doors and (b) to determine how vision contributed to this behaviour. Participants (N = 6) walked along a 7-m path toward two motor-driven doors, which moved at rates ranging between 20 and 40 cm/s. Each door was independently driven such that both moved at the same velocity (symmetrical) or at different velocities (asymmetrical). The results showed that in both door movement conditions the participants controlled their approach velocity by slowing down prior to crossing the doors. The decrease in walking velocity produced greater velocity variability in the final stages prior to crossing the doors and high success rates. The results from the gaze behaviours showed that fixation durations were significantly longer when the doors moved asymmetrically, suggesting that the visual information from this unpredictable environment took longer to process. However, the fixation patterns were similar between the two door movement conditions. Regardless of the door movement condition, the participants spent about 60% of each trial fixating environmental objects (i.e., left door, right door, or aperture). The majority of fixations were directed towards one of the doors at the beginning of the trial and then shifted towards the aperture in the final phase. The participants were using perception-action coupling to control their behaviours in the final phase in order to steer locomotion through the aperture.