The error-related negativity (ERN) is an event-related brain potential observed when subjects commit errors. To examine whether the ERN is sensitive to the value of errors, the motivational significance of errors was manipulated in two experiments. In Experiment 1, low and high monetary value errors were compared to evaluate the effect of trial value on the ERN. In Experiment 2, subjects performed a flanker task both while their performance was being evaluated and during a control condition. Consistent with the notion that the error-detection system is sensitive to the significance of errors, the ERN was significantly larger on high-value trials in Experiment 1 and during evaluation in Experiment 2. There were no corresponding effects on the correct response negativity, and no behavioral differences between conditions were evident in either experiment. These results are discussed in terms of the functional role of the ERN in response monitoring.Descriptors: Motivation, Event-related potentials (ERPs), Error-related negativity (ERN), Ne, Value, Affect Effective action monitoring involves appropriate performance adjustments in terms of task demands, and a crucial component of this process is the ability to detect errors and adjust performance accordingly (Falkenstein, Hoormann, Christ, & Hohnsbein, 2000). Studies that measure response-locked eventrelated brain potentials (ERPs) have described fronto-centrally maximal negative components that appear relevant to response monitoring. Perhaps most notably, when subjects make a mistake, the response-locked ERP at fronto-central recording sites is characterized by a negative deflection known as the error-related negativity (ERN or Ne) that peaks approximately 50 ms postresponse (Falkenstein et al., 2000;Falkenstein, Hohnsbein, Hoormann, & Blanke, 1991;Gehring, Coles, Meyer, & Donchin, 1990; Gerhing, Goss, Coles, Meyer, & Donchin, 1993;Holroyd & Coles, 2002;Nieuwenhuis, Ridderinkhof, Blom, Band, & Kok, 2001).Because the ERN has been observed across different stimulus and response modalities, it is thought to reflect the activity of a generic response monitoring system (Bernstein, Scheffers, & Coles, 1995;Dehaene, Posner, & Tucker, 1994;Falkenstein et al., 1991Falkenstein et al., , 2000Holroyd, Dien, & Coles, 1998;Luu, Flaisch, & Tucker, 2000;Miltner, Braun, & Coles, 1997;Van 't Ent & Apkarian, 1999). Studies utilizing source localization suggest that the ERN is generated in the medial frontal cortex, most likely the anterior cingulate cortex (ACC; Dehaene et al., 1994;Holroyd et al., 1998;Miltner et al., 1997).In addition to the ERN, a small negative deflection has also been observed in the response-locked ERP on correct trials. This correct response negativity (CRN) appears to have morphological and topographical properties similar to the ERN (Vidal, Burle, Bonnet, Grapperon, & Hasbroucq, 2003;Vidal, Hasbroucq, Grapperon, & Bonnet, 2000). Although the functional significance of the CRN is unknown, the similarities between the ERN and CRN suggest that both compon...