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Abstract:
In reaction time and typing tasks, error responses are less
forceful than correct responses. Why this is so remains unclear:
the error response may be weak, corrective responses may compete
with the error, or inhibitory processes may suppress the error once
it is detected. We report data suggesting that error detection and
response inhibition contribute to this effect. Participants made
speeded isometric elbow extension responses in an Eriksen flanker
task. We measured response force, agonist (triceps) and antagonist
(biceps) electromyographic (EMG) activity, and the error-related
negativity (ERN), an event-related brain potential component
hypothesized to reflect medial frontal activity involved in
detecting errors or response conflict. Error responses were less
forceful and showed less agonist EMG than correct responses. Errors
were less forceful than correct responses when trials were matched
for agonist EMG amplitude, suggesting that errors are not simply
weak responses. Antagonist EMG was larger on error trials than on
correct trials, consistent with a response inhibition mechanism.
Similarly, antagonist EMG (as a proportion of agonist EMG) was
larger when errors were less forceful than when they were more
forceful. The ERN occurred earlier when errors were less forceful,
consistent with the hypothesis that effective error inhibition
depends on rapid detection of the error. These data suggest that
error detection gives rise to processes that suppress the error
response.
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