This study investigated whether error-related negativity (ERN) elicited by partial errors and No-go N2 represent distinct or similar components. We also investigated whether the error positivity (Pe) and No-go P3 represent distinct or similar components. Partial-error trials are behaviourally classified as correct trials but preceded by covert muscular activities. Recent studies have reported that analysing partial-error trials is useful for investigating the functional roles of ERN and No-go N2. In this study, 23 participants performed a Go/No-go flanker task. They performed nine blocks of 60 trials each. Stimulus-locked event-related potentials (ERPs) were averaged separately for Go-congruent pure-correct trials, Go-incongruent pure-correct trials and No-go pure-correct trials. In addition, we compared the stimulus-locked ERPs among No-go pure-correct trials, No-go partial-error trials, Go-incongruent pure-correct trials and Go-incongruent partial-error trials. Electromyogram (EMG)-locked ERPs were averaged separately for correct trials, overt errors in No-go trials, partial errors in No-go trials, overt errors in incongruent trials and partial errors in incongruent trials. N2 was remarkably larger in No-go partial-error trials than in No-go pure-correct trials. Consistent with previous findings, the No-go partial-error N2 might reflect error-related processing. P3 amplitudes were larger in the No-go trials than in both the Go-congruent and Go-incongruent trials. These results suggest that the No-go P3, but not the No-go N2, might reflect inhibition of overt movement. The present findings provide further evidence that the previously reported increase in No-go N2 may be due to an overlap of the ERN elicited by partial errors.
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