Perceptual and motor contributions to performance and ERP components after incorrect motor activation in a flanker reaction task

Objectives: The aims of this study are to evaluate contributions of response and perceptual processes to reaction performance in a flanker reaction task, and to investigate whether event-related potential (ERP) component N2 and error negativity Ne represent similar or functionally distinct cortical mechanisms. Methods: ERPs, lateralized readiness potentials (LRPs) and reaction performance were measured in a flanker task with arrows as targets and congruent or incongruent flankers. Squares were used as neutral flankers. Target color signaled a response of the hand indicated by (PRO) or against (ANTI) the target arrow's pointing direction. Results: On both PRO and ANTI conditions, performance was facilitated by congruent and impaired by incongruent flankers. In the ERPs on trials with late response errors an N2 was evident before an Ne. In addition, ERPs on correct trials showed an N2 particularly after incongruent flankers on PRO but for each flanker type on ANTI conditions. On incongruent ANTI trials, two successive response conflicts occurred but only a single N2 appeared. Conclusions: The results indicate that differences in perceptual processing contribute significantly to the flanker effects on task performance and provide further evidence that N2 and Ne represent different cortical mechanisms. The data also suggest that N2 is not a real-time correlate of incorrect response suppression.

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