Coding theory adapted to gait perception.

Restle's coding theory for movement perception is merged with certain aspects of Johansson's vector descriptions of movement to investigate the relative per-ceptual prominence of several kinds of displays of human walkers. Two versions of a coding model are entertained. The first considers the results of a demon-stration and an experiment in which points of light are mounted in either of two ways: on major joints of the body or off them. Results suggest that on-joint displays are the better figures but that off-joint displays are fully adequate for representing human motion. Vector codes and a system for relating them are developed to reflect these results. This first model, however, is inadequate for a second demonstration in which the spatial relations among the lights are scram-bled. The model's problem lies in the fact that it does not discriminate between a canonical walker display and the spatially anomalous one. Thus, the model is elaborated into a second form to account for the difference. It incorporates what my colleagues and I have called centers of moment. The force of this exercise is to demonstrate the necessity for movements and spatial extent to be coded