Although mental practice has often been demonstrated to result in improved learning of a motor skill, theoretical accounts of the reasons for this improvement are lacking. The present experiment examined the role of knowledge of results (KR) in motor skill learning, because KR is believed to be crucial to such learning, yet is lacking during mental practice. Subjects in four conditions (mental practice, physical practice, physical practice without KR, and control), tossed beanbags at a target. Results showed that of the four conditions, mental practice showed the largest performance increment, whereas physical practice showed a decrement attributed to massed practice without adequate rest periods. Results suggest that (a) knowledge of results is not always essential for improved performance; (b) mental practice is most beneficial following sufficient experience with the task; and (c) mental practice may be best suited for a massed practice learning situation.
Requests for reprints and other correspondence concerning this article should be sent to Steven G. Zecker, Department of Psychology, Hamilton College, Clinton, NY 13323.