Individuals with anxiety disorders and related personality traits are characterized by increased error-related brain activity, as measured by the error-related negativity (ERN) in simple speeded response tasks. An absent, or opposite, relation between anxiety and the ERN has been reported in studies that employed reinforcement learning paradigms with trial-to-trial feedback. Understanding the effect of trial-to-trial feedback on the ERN may help clarify these results and can further elucidate the impact of feedback on performance monitoring. In the present study, 30 undergraduate participants performed two versions of the arrowhead version of the flanker task in counterbalanced order: one with trial-to-trial feedback and one without. The participants were slower and more accurate in the task with trial-to-trial feedback; however, the ERN was equivalent between the two tasks. Larger ERNs were related to higher trait anxiety, but only in the version without trial-to-trial feedback. These findings show that although trial-to-trial performance feedback impacts behavioral measures, it does not affect the ERN; moreover, the presence of trial-to-trial feedback moderates the relationship between the ERN and anxiety.