STIMULUS CONGRUENCE AND STIMULUS-RESPONSE COMPATIBILITY - 2 VARIABLES DISENTANGLED IN AN AUDITORY REACTION-TIME-TASK

Stimulus-response (S-R) compatibility was a term first used by Fitts and Seeger (1953) to describe effects observed on reaction time (RT) when the stimulus-response relationship was varied, as in the following instructions: "move to the right when the stimulus appears on the right" (compatible) or "move to the left when the stimulus appears on the right" (incompatible). This term was later employed in a broader sense (Simon & Rudell, 1967) with paradigms involving elaborate stimuli, such as the verbal command "RIGHT" delivered to the right ear (compatible) or to the left ear (incompatible). In such paradigms, subjects respond faster when the response is delivered on the same side as the stimulus (the so-called "Simon effect"). It has been shown, however, that this effect could be reversed under some circumstances in the visual domain. In this paper, we report data showing that it can also be reversed in the auditory domain when using the above-mentioned verbal commands. This brings further evidence that stimulus-response compatibility and the Simon effect differ in essence, with the latter effect reflecting the influence of stimulus congruence, the correspondence relationship borne by the two simultaneous characteristics of the stimulus. Stimulus congruence and stimulus-response compatibility had indeed independent influences on RT, which in a serially connected information-processing model would imply that they act upon independent stages.