Response preparation and control of movement sequences.

Two experiments investigated the response complexity effect using elbow extension/flexion movements. In Exp 1 with 30 undergraduates, reaction time (RT) for an extension movement was significantly less than RT for an extension/flexion movement. However, this difference in RT was not evident when participants were asked to pause at the reversal of the extension/flexion for approximately 260 msec. Exp 2 with 10 undergraduates manipulated the duration of the pause between these movements and also measured the electromyographical activity of the triceps and biceps muscles. When the pause was reduced to 75 msec, Ss were not able to program the flexion portion of the movement at the reversal, forcing them to preprogram this movement: hence, increasing their premotor RT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)