Is it possible to prepare the second component of a movement before the first one?

Experiment 1 utilized a choice reaction time paradigm to examine whether advance information about the second component of a movement has similar effects upon movement initiation and execution as advance information about the first component. Four stimuli were assigned to four goal keys. Subjects responded with the index finger of their preferred hand. They had to press on of two intermediate keys before pressing the assigned stimulus goal key. Advance information signaled one pair of goal keys in such a way that either the first or the second movement component was unequivocally specified before the response signal appeared. Shorter reaction times resulted when the first component was precued. Further control conditions showed that advance information about the second movement component could not be utilized for movement preparation. Experiment 2 ruled out a perceptual interpretation of this effect. Experiment 3 showed that preparation time for two-component movements are longer than for one-component movements. The study permits the conclusions that speeded two-component movements are controlled by motor programs and that advance information about the first movement component is required before the second movement component can be programmed.