Error-preceding brain activity: robustness, temporal dynamics, and boundary conditions.

A recent study reported a positive modulation of the response-locked event-related brain potential (ERP) on trials preceding errors (i.e., error-1 trials). It was proposed that this error-preceding positivity (EPP) reflects the disengagement of the response monitoring system prior to errors. In three studies, we sought to replicate the EPP, and to delineate the conditions under which it can be observed. Study 1 replicated the finding of a positive modulation of the ERP on error-preceding compared to RT-matched correct-preceding trials. This enhanced positivity was not due to differences in stimulus-related processing, and a similar modulation was not observed on error-2 or error+1 trials. Studies 2 and 3 indicated that similar EPP-like phenomena could be observed across a variety of tasks, and using much longer inter-trial intervals. The onset and duration of the modulation, however, did vary between studies. These results are discussed in terms of response-locked ERPs and action monitoring.