The original version of the conflict monitoring theory does not account for the CRN. In the conflict monitoring theory, increased conflict should occur prior to the response on correct trials but after the response on error trials (Yeung et al., 2004). However, it has recently been suggested that conflict might occur at multiple levels. Van Veen and Carter (2005) studied both stimulus and response conflict while participants performed a Stroop task. They found that although the ACC was active during both forms of conflict, specific regions of the ACC differed, which suggests that different forms of conflict processing occur in parallel. Therefore, CRN might be related to conflict at the response level. In fact, work by Bartholow and colleagues indicates that incompatible trials yield a larger CRN amplitude than compatible trials (Bartholow et al., 2005). Thus, the relatively new suggestion that conflict may influence ERPs at multiple levels of stimulus and response processing appears to allow for the possibility that the ERN and CRN, as well as the stimulus-locked N2, reflect conflict monitoring.
