Relation of repetition effect and response programming in a speeded choice task.

The present study tested the hypothesis that the repetition effect occurs during response programming. The choice reaction-time to initiate the second of two responses was examined when two consecutive responses were the same or different in their kinematics and force characteristics and repeated for two different stimuli. 12 subjects were required to react and produce the sequence of same or different force by squeezing a handle as quickly and accurately as possible after the first (auditory) and the second (visual) reaction signals. The response-stimulus interval was set at 500 msec. The choice reaction-time to initiate the second response was significantly shorter for the same-force condition than for the different-force and control conditions. This result indicates that the repetition effect originates in a speedup in response programming rather than response selection or perceptual identification. This finding was discussed in terms of bypassing a response-programming stage.