An electromyographic investigation of the effect of stimulus-response mapping on choice reaction time

The activity of the agonist muscles was recorded during the performance of a two-choice visual reaction time (RT) task in which the compatibility of t he stimulus-response mapping was manipulated. Correct trials were distingui shed according to whether or not the activation of the agonist of the requi red response was preceded by an activation of the agonist of the nonrequire d response. Double activation trials were more numerous for the incompatibl e than for the compatible mapping. Furthermore, these trials yielded longer RTs than the single muscular activation trials. These results suggest that initial activations of nonrequired responses are more frequently aborted a nd corrected when the mapping is incompatible than when it is compatible. T his finding supports the dimensional overlap model of stimulus-response com patibility (S. Kornblum, T Hasbroucq, & A. Osman, 1990).