Event-related potentials in a decision-making task with delayed and immediate reward conditions

We investigated performance monitoring of a group of healthy normal subjects in a delay of gratification paradigm. Focusing on response-locked event-related brain potentials we observed an Ne-Pe-like complex in all conditions. While there was no modulation of the Ne-like component, the subsequent Pe-like positivity was largest in conditions in which subjects went for the largest immediate reward, regardless of whether this was disadvantageous (i.e., foreclosed a larger delayed reward) or not. We interpreted the positivity as mainly reflecting the size of the immediate reward.