Stimulus-response compatibility and the motor system

Three experiments examined stimulus-response (S--R) compatibility relationships with the stimulus array perpendicular to the response array. In Experiments I and II, stimuli indicated right and left positions, while the responses were movements up and down. The mapping right/up and left/down was preferable for the right hand, but the reverse mapping was preferable for the left hand. In Experiment III, the stimuli indicated up and down positions, while the responses were movements to the right and left. In this case, the mapping up/left and down/right was preferable for the right hand, and the reverse mapping was preferable for the left hand. The results are most easily explained by assuming that counterclockwise rotational movements are preferable for the right hand, while clockwise is preferable for the left. These preferences are manifest through combinations of implicit movements towards the stimulus and explicit movements towards the response key. This principle is shown to provide a simpler explanation for some previously reported S-R compatibility effects.