Abstract
We investigated the ability of the visual-motor system to adapt to discrepancies between visual and physical information about self-motion, and whether adaptation depends on the presence of rich optic flow. Subjects walked to visible targets 6 m away in an virtual environment presented with a head-mounted display. During adaptation trials, visual space was rotated relative to physical space such that subjects' visual heading specified by optic flow deviated from their physical heading by 10°, which caused subjects to walk along curved paths to the goal. Subjects were unaware of these conflicts. In separate blocks, we tested two simulated environments, one with a textured ground plane that provided optic flow throughout the 45° field of view, and another with a homogeneous ground plane. Over the course of 20 adaptation trials, subjects adapted to partially compensate for the conflicts, resulting in straighter paths. When the conflicts were removed post-adaptation, subjects showed aftereffects in the opposite direction. The amount of adaptation was similar for textured and homogeneous ground conditions (20–25%), with the textured environment producing slightly faster adaptation and larger aftereffects. We conclude that the visual-motor system can rapidly re-calibrate the mapping from physical to visual heading, and that this adaptation does not strongly depend on full-field optic flow.