Exploration in the service of prospective control

We propose a sequential process of exploration that can account for perception-action coupling in infant locomotion. Each phase in the sequence is a process of obtaining progressively more information leading to a motor decision-exploration from a distance, exploration via direct contact, and exploration of alternative means. Quick glances and prolonged looking from afar serve to alert the perceiver to important changes in the terrain. Intentional touching and testing alternative ways to traverse an obstacle are only prompted when prior information indicates a potential threat to balance. We further propose that depth information is privileged because it can be detected from a distance more readily than other surface properties such as rigidity and friction. Studies of infants walking down slopes and across "hole/patch" transitions illustrate the important role of exploration in prospective control of locomotion. (C) 2000 Elsevier Science Inc. All rights reserved.