Evidence for Abstract Response Codes: Ear-Hand Correspondence Effects in a Three-Choice Reaction-Time Task

A three-choice reaction-time task was used to investigate the source-of-stimulation effect, that is, the tendency for subjects to react faster and more accurately to a stimulus if the spatial locations of the stimulus and the response correspond than if they do not. Auditory stimuli varied on dimensions of tonal frequency and spatial location, although only the former was relevant for response selection. Responses were found to be faster for the conditions in which stimulus location and response location corresponded than for those in which they did not, but stimulus location had no effect on differences between the two hands with bimanual responses. These results support the hypothesis that the source-of-stimulation effect is due to response plans which interact at a level prior to the programming of the motor response.