To Cross or Not to Cross: The Effect of Locomotion on Street-Crossing Behavior

Perception of some affordances requires action scaling rather than simply body (size) scaling. Crossing a road safely is such an affordance. Perceiving accurately whether crossing in front of oncoming traffic is possible entails perceiving the relation between environmental properties (the to-be-crossed distance and the available time) and one's walking abilities. Only while walking is perceptual information about walking abilities available; hence, a more accurate perception of whether crossing is possible is expected than when stationary. We observed crossing behavior (stopping, staying, and crossing) at a crosswalk and related this behavior to the time that was available before the next vehicle arrived. The critical time gap that separated not crossing (stopping or staying) and crossing was smaller, that is, closer to the actual crossing time, when walking than when standing still. Thus, crossing from standstill entailed a larger safety margin. This suggests that information about ongoing action can yield more accurate perception of the affordance in question.