Processing demands during movement

Subjects made a speeded stylus movement along a track to a stop and simultaneously performed a simple reaction-time task designed to assess the processing demands of the movement task. Movement task variables were: (a) number of alternative ending positions - either one or two - with the choice executed during movement, and (b) presentation time for the endpoint signals in the two-choice conditions, either prior to movement initiation (immediate) or during movement execution (delay). Processing demands were higher during all movement conditions than in a control condition that did not require movement. Processing demands during execution of the one-and two-choice movement with immediate signals did not differ. However, processing demands during the two-choice movements with delayed signals were higher than demands during the two-choice movement with immediate signals.