CONTRIBUTIONS OF PREMOTOR AND MOTOR TIMES TO STIMULUS-RESPONSE COMPATIBILITY EFFECTS

The present study examined the premotor and motor components of fractionated reaction times (RT) for stimulus-response (S-R) compatibility effects. Eight subjects participated in two separate blocks, with one block using a compatible S-R assignment and the other using an incompatible assignment. For both assignments, the task was to lift the left or right hand in response to a left or right visual stimulus. In the compatible assignment, the left stimulus was assigned to the left hand, and the right stimulus was assigned to the right hand. In the compatible assignment, the assignments were crossed (e.g., left stimulus to right hand). Electromyographies from the primary movers of the lift motion of the hands (e.g., wrist extensors) were used for fractionating RTs into premotor and motor components. The analysis of the fractionated RTs indicated that the difference between the compatible and incompatible S-R assignments is attributed to premotor processes. S-R compatibility effects arise entirely from the central processing stages.