Percept-based and object-based error processing: An experimental dissociation of error-related negativity and error positivity

Objective: Investigated the effect of presentation duration of masked visual stimuli and presentation mode (randomized, blocked) on error-related negativity (ERN) and error positivity (Pe). Method: In two experiments, participants responded with the left and right hand to leftward and rightward arrows presented for different durations (0-117 ms). Different stimulus durations were fully randomized in Experiment 1 but run in separate blocks in Experiment 2. Results: In both experiments, percent correct and Pe amplitude increased with increasing stimulus duration. By contrast, ERN was only found for (blocked) longer stimulus durations of Experiment 2, and absent with the randomized stimulus durations of Experiment 1. Conclusions: Presence of a Pe in the absence of ERN in Experiment 1 suggests that conscious error processing can occur without prior unconscious error detection. To explain the pattern of ERN/Pe effects, two separate processes of error detection are suggested, operating independently at the levels of object-based (Pe) and purely perceptual stimulus representations (ERN), respectively. Significance: A novel model of error processing is developed, elaborating on the reinforcement-learning theory of ERN. It is suggested that giving a response retrieves appropriate stimulus representations whose activation typically precedes this response; in case of mismatch with actually present stimuli, ERN is elicited. (C) 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.