Phenomenal Versus Process Explanations of Prism Aftereffects

Abstract
The phenomenal hypothesis that prism aftereffects depend upon sight of the limb was tested in a ball-throwing task during prism exposure; the participant's (N = 28) limb was either visible or not visible, but feedback from the moving ball was available during the exposure. Aftereffects were clearly demonstrated in both the visible- and nonvisible-limb conditions, and total aftereffect was larger for participants in the nonvisible-limb condition. Proprioceptive aftereffects were greater than visual aftereffects in the visible-limb group; however, the reverse was true for the nonvisible-limb group. Those results support a processing hypothesis in which sensory feedback, not phenomenal experience, is necessary.