Reaction time in retarded and nonretarded young adults: sequential effects and response organization

Two types of sequential effects can occur in 2-choice reaction-time (RT) tasks. In an alternation effect, the RT for a response that differs from the previous response is faster than that for a response that is the same. In a repetition effect, the opposite is the case; i.e., the RT for a response that is the same as the previous response is faster than that for a different response. These effects were investigated in a comparison of retarded and nonretarded subjects in a 2 choice RT task. There were three conditions that differed in the degree of response organization required. For the retarded subjects, both a significant increase in the overall mean RT and a change from alternation to repetition effects were found with increasing degree of response organization. Neither result was found for the nonretarded subjects. For both groups there was a tendency for alternation effects to decrease and repetition effects to increase with decreasing intelligence. Overall, sequential effects were found to correlate more consistently than mean RT with both degree of response organization and intelligence.