Temporal anticipation of response initiation by mentally retarded persons

The ability of retarded persons to anticipate a signal to initiate discrete movements of varying complexity was investigated in two experiments. The results revealed an interaction between temporal anticipation and response complexity. Experiment 1 showed no reduction in reaction time (RT) in discrete aiming movements when the foreperiod was changed from a random interval to a fixed interval (1 or 3 seconds). Reaction time did not vary with length of the interval or the difficulty of the movement. Experiment 2 showed a reduction of RT to a simple release response at a fixed 1-second warning interval. The findings reflect the difficulty retarded persons have in programming more complex movements and the interaction of temporal anticipation in this response-initiation process.