The problem of rehearsal or mental practice.

The present study examines several methodological and conceptual problems which in the past have made it difficult to accept the hypothesis that mental practice facilitates behavioral skill. An experiment on skill in speech production is then reported which overcomes the methodological problems. Subjects practice producing a sentence at maximal rate either mentally (mental practice) or overtly (physical practice) and then produced a transfer sentence which was either related or unrelated. The maximal rate of speech was faster for related than unrelated transfer sentences, and the degree of transfer for the mental and physical practice conditions was equivalent. A theory was developed to explain these results and overcome the conceptual problems outlined in the introduction. Implications of the theory for several related phenomena are discussed: rehearsal, errors in action, automatization, control processes in motor skills, speed-up as a function of practice, the relative advantages of physical vs. mental practice, and the evoked potentials accompanying mental rehearsal of an action.