Abstract
Adaptation effects from prolonged or repeated exposure to particular visual stimulus features have been shown for motion and color, as well as higher-order stimulus dimensions such as face identity. More recently, adaptation effects from viewing particular biological motion patterns, such as male or female gait, have been reported. Here we examined if adaptation to gait relies on form cues, such as body configuration, or if the local trajectory of individual limbs is sufficient. Participants (N=16) viewed an animated figure walking with a gait that consisted of a spatiotemporal morph between gait styles captured from two different human actors. The walking figure was configured either as intact, or apart with the limbs and torso separated but maintaining the same motion trajectory as the intact figure. Using a double staircase procedure we determined the point of subjective equality (PSE) between the two gaits for intact and apart test walkers, before and after 2mins (plus 5secs/trial top-up) adaptation to one of the gaits. Adaptation to intact or apart figures was conducted in sessions separated by at least 48hrs. Results revealed strong within-stimulus adaptation, with the intact walker adapting the intact test walker, and the apart walker adapting the apart test walker. However, there was asymmetric transfer across the two configurations, as the intact walker adapted the apart test walker, but the apart walker did not adapt the intact test walker. These findings cannot be explained by weaker adaptation to the apart walker in general. Instead they show that when there is conflict between the configural cues of adaptor and test stimuli, observers show a preference for the intact stimulus. While prior exposure to the local motion trajectory of the individual limbs and torso can bias our internal representation of gait, the presence of form cues such as body configuration will override this bias.
This project was supported in part by the Army Research Laboratory Human Research and Engineering Directorate (ARL-HRED).