Motor components in the choice reaction time of mildly retarded adults.

The contributions of specific motor-coordination disabilities and general slowness of motor function to the choice reaction times (RTs) of retarded subjects were examined in two experiments. RTs for the same stimulus-response (S-R) pairs were markedly shorter when presented in 2-choice than in 8-choice RT situations. Furthermore, in an 8-choice task, large RT differences between retarded and nonretarded subjects decreased markedly when processes of stimulus discrimination and S-R translation were minimized by direct stimulation of the response mechanisms.