On-line action monitoring of response execution: An electrophysiological study

•Subthreshold correct EMG activities (“partial correct”) preceding correct responses seem to reflect action monitoring of response execution.•Response force is smaller on trials preceding a trial containing a partial correct activation.•Error Negativity, evoked by partial correct activations is larger than Error Negativity evoked by correct responses.•Action monitoring is competent regarding the force parameter.

In between-hand choice-RT-tasks, small incorrect EMG activations occurring before the correct response (“partial errors”) are assumed to reflect the detection, inhibition and correction of erroneous hand selection, revealing the existence of an action monitoring system, acting “on-line”.Now, EMG activations of the correctly selected hand muscles, too small to reach the response threshold, may also occur before these hand muscles produce an overt correct response (“partial corrects”). We hypothesized that partial corrects reflect incorrect execution of correctly selected responses. We found 1) that response force was smaller on trials preceding a partial correct trial and 2) that the Error Negativity, a performance sensitive ERP, assumed to reveal “on-line” action monitoring, was larger for partial corrects than for correct trials.This also suggests that the competence of the action monitoring system is not restricted to selection errors but also extends to execution errors.