Spatial Updating of Self-Position and Orientation During Real, Imagined, and Virtual Locomotion

Two studies investigated updating of self-position and heading during real, imagined, and simulated locomotion. Subjects were exposed to a two-segment path with a turn between segments; they responded by turning to face the origin as they would if they had walked the path and were at the end of the second segment. The conditions of pathway exposure included physical walking, imagined walking from a verbal description, watching another person walk, and experiencing optic flow that simulated walking, with or without a physical turn between the path segments. If subjects failed to update an internal representation of heading, but did encode the pathway trajectory, they should have overturned by the magnitude of the turn between the path segments. Such systematic overturning was found in the description and watching conditions, but not with physical walking. Simulated optic flow was not by itself sufficient to induce spatial updating that supported correct turn responses.