In the current study, we examined brain responses to feedback stimuli in a gambling task in order to: (1) evaluate the relationship between externalizing proneness and FRN response, and (2) replicate the finding of an association between externalizing proneness and reduced P300 amplitude within a new task paradigm, distinct from oddball tasks used in most P300 studies to date. Identifying the relationship between the FRN and externalizing proneness was important to determining whether the ERN amplitude reductions associated with externalizing proneness (reflecting deficits in monitoring on the basis of internal representations) generalize to the FRN (i.e., monitoring on the basis of exogenous cues). Exploring the relationship between externalizing proneness and P300 amplitude within an alternative, feedback-stimulus paradigm was important for evaluating the generality of the association between P300 and externalizing proneness.
