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 the stimulus–response
mapping was manipulated. Correct trials were distinguished
according to whether or not the activation of the agonist
of the required response was preceded by an activation
of the agonist of the nonrequired response. Double activation
trials were more numerous for the incompatible 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 and corrected when
the mapping is incompatible than when it is compatible.
This finding supports the dimensional overlap model of
stimulus–response compatibility (S. Kornblum, T.
Hasbroucq, & A. Osman, 1990).