Integrating multiple perspectives on error-related brain activity: The ERN as a neural indicator of trait defensive reactivity

In the past 20 years, research concerning the error-related negativity (ERN), a negative-going deflection in the event-related brain potential (ERP) following an erroneous response, has flourished. Despite a substantial body of research, debate regarding its functional significance persists. In what follows, we selectively review literature on the ERN, and outline several prominent cognitive theories related to the generation and significance of the ERN. Cognitive theories predict that the size of the ERN should relate to variation in behavior, although there is substantial evidence that the ERN and behavioral measures are at least partially dissociable. Moreover, individual difference measures, psychopathology, and motivational factors all appear to impact basic mechanisms that generate the ERN to moderate the magnitude of the ERN, suggesting a need to integrate alternative perspectives into models of ERN amplitude. Insofar as errors prompt the mobilization of defensive responses, we view variation in the ERN in terms of error detection in the service of protecting the organism. Based on data indicating that the ERN is highly stable over time, heritable, and related to broad dimensions of personality, we propose that the ERN is a neural index of a neurobehavioral trait and variation in its amplitude is related in part to individual differences in defensive reactivity. Implications and future directions are considered.