Conflict and inhibition in the cued-Go/NoGo task

Objective: Current debate centres on the inhibitory and conflict interpretations of the N2 and P3 components of the event-related potential (ERP). We examined behavioural responses and ERPs in a cued-Go/NoGo task. Methods: Participants were required to inhibit a planned response (NoGo target after Go cue), change a planned response to a different one (Invalid cueing), and activate an unexpected response (Go target after NoGo cue). Results: Responses were slower when participants had to change a planned response, and execute an unplanned response. N2 was more negative whenever the presented target required a different response to what was expected based on the cue. In contrast, P3 was increased when participants had to change or inhibit a planned response, but not when executing a response where none was planned. Conclusions: N2 results lend support to the conflict account, while P3 reflects cancellation of a planned response. Significance: This paper provides the first test of conflict involving activation of an unplanned response in a cued-Go/NoGo task. (C) 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.