Overt and covert rehearsal in short-term motor memory of mentally retarded and nonretarded persons.

Overt rehearsal and the presence of covert rehearsal in short-term motor memory of a retarded group and two nonretarded groups of students (n = 100 in each group) was investigated. Subjects were randomly assigned to five retention conditions: immediate recall, a 20-second unfilled interval, a 20-second interval filled with interpolated mental activity, a 20-second interval of overt rehearsal, and a 20-second interval filled with simultaneous overt rehearsal and interpolated mental activity. Results indicated that retarded persons did not engage in spontaneous covert rehearsal of motor information while nonretarded persons did. The short-term motor memory of retarded and nonretarded groups was not different when covert rehearsal was not possible and during overt rehearsal. In general, however, overt rehearsal did not facilitate motor memory.