Arguments and evidence are presented that prism adaptation results in a third end state in addition to the ‘traditional’ components of ‘proprioceptive shift’ and ‘visual shift’. That is, under certain conditions (most importantly, ones involving error-corrective feedback), exposure to prism-displaced vision induces a motor-learning component, referred to here as an ‘assimilated corrective response’. Thus the postexposure error in target pointing, the ‘negative aftereffect’, is postulated to be the algebraic sum of proprioceptive shift, visual shift, and an assimilated corrective response—at least in certain situations. Support for the existence of this third component as a form of learning is seen in the fact that it occurs primarily when prism exposure involves target-pointing experience, and that it is apparently subject to the effects of some ‘learning variables’.
Quantitative Evaluation of Human Cerebellum-Dependent Motor Learning through Prism Adaptation of Hand-Reaching Movement
