In summary, our work has several important implications. First, our data suggest that the feedback monitoring system continues to develop across the range of participants we studied. Because we used tightly constructed age brackets, we can say that the maturational changes on the FRN appear to emerge in the transition from early (13–14 yrs.) to middle adolescence (15–17 yrs.). This was evident for FRN amplitude, as well as for FRN latency, which linearly decreased with age group. Second, developmental effects reported here do not appear to be an artifact of learning, as we used a chance-based task. Third, sex was an important explanatory factor with males generally producing larger feedback responses, longer ERP latencies for rewarded feedback, greater ERP feedback response overall, and greater feedback activity localized to the subgenual ACC. Future work is needed to unpack these sex differences, which may have implications for how reward processing is studied across the sexes. Clearly sex needs to be included as a factor in analyses and reported in studies of ERP feedback processing.
