Movement coding and memory in retarded children

Three experiments on the coding and retention of movement-generated information were performed on two groups of mildly retarded children varying in MA. The cue to be reproduced in each case was the terminal position of the limb that studies with adults have shown to require central processing activity for maintained performance. In Experiment 1, although the older MA group was superior, both groups showed similar decrements in performance over a 15-second retention interval. In Experiment 2 the procedures were adopted in an attempt to overcome performance deficits. Subjects were allowed to choose (preselect) their own movements voluntarily in addition to performing constrained, experimenter-defined movements. Preselected reproduction was superior to constrained at all three retention intervals (0, 7, and 15 seconds) but was not statistically different among age groups. Also, performance was maintained for both groups over 7 seconds but deteriorated over 15 seconds. These results were replicated in Experiment 3, which also showed that an interpolated motor task designed to block rehearsal processes interfered with reproduction at the 7- and 15-second retention-interval conditions. The findings indicated that mildly retarded children could maintain motor information over brief time periods and also illustrated the important contribution of the planning component in facilitating the coding of motoric information.