The Utility of not Changing Direction and the Visual Guidance of Locomotion

Abstract

In this chapter we describe how the simple heuristic maintain egocentric direction of the target and the associated heuristic cancel target drift can, in theory, be used to successfully visually guide an observer around an environment. The motivation for this chapter is the proposal by Rushton et al. (1998) that observers visually guide locomotion using perceived egocentric target direction rather than optic flow. We concentrate on the visual control aspects of self-motion. The other approach is to develop models that capture the walking behavior of an observer attempting to reach a target. These models describe the final avoidance or closure behavior, rather than just the visual control laws themselves. Therefore they include terms such as a “damping” parameter and take into account perceptuo-motor processing delays. These terms reflect the physical embodiment of the observer, specifically, the physical limitations of the observer. An observer can only process information so fast, and the observer’s body has a mass whose velocity must be regulated.