subject samples under study. Kamarajan et al. [150] used an abstinent alcoholic sample (DSM-IV) whereas Bernat et al. [151] used a sample of undergraduate students who were classified into high and low proneness to externalizing. Secondly, Kamarajan et al. [150] used an S-Transform analysis to decompose TF signals where a broader time window of 200-500 ms was used that encompasses both outcome-related negativity and positivity (ORN/ORP). On the other hand, Bernat et al. [151] used a PCA based TF approach and included the components that accounted for most of the variance; i.e., they separated contributions of the delta (P3) and theta (FRN) time windows. It has been reported that P3 is primarily composed of delta and theta oscillations [72-78] and N2 is primarily composed of theta oscillations (e.g., [133,134,136,137,153]). Therefore, the differences in study samples and methodological approaches in these two studies may explain the contrasting results, but further studies will be required to resolve these issues.
