The Additivity of Stimulus-response Compatibility with the Effects of Sensory and Motor Factors in a Tactile Choice Reaction Time Task *

A classic finding in the choice reaction time (RT) literature is that RT is faster when stimulus and response correspond in the external space (compatible mapping) than when they do not correspond (incompatible mapping); e.g. Fitts and Deininger (1954). This effect is independent of the anatomical identity of the effecters involved in the task (Brebner et al. 1972) as well as of the amplitude (Guiard 1983) and velocity (Spijkers and Walter 1985) of the movement to be completed for the response. These findings suggest that the mapping effect in these tasks is mediated by an information processing stage (Smith 1968) in which stimuli and responses are paired within a common