Continuous versus Terminal Visual Feedback in Prism Aftereffects

Abstract

Ss wore prisms as they reached for a visible target with one hand. When the reaching hand was viewed continuously, aftereffects were restricted to that hand. When the reaching hand was viewed only after each reaching movement had already been completed, aftereffects were obtained with both hands. These findings dispute the generality of assertions that the aftereffects of wearing prisms are exclusively a result of either changes in the sensed position of the prismatically viewed arm or changes in the judgment of the direction of the gaze. Rather, both appear to be possible mechanisms underlying the aftereffects, and their relative prominence depends strongly upon visual feedback conditions.