Due to their robustness against departures from normality, nonparametric statistical tests were used. To evaluate the effect of stimulus on the ERPs and TF-energy PCs, we preformed Wilcoxon Signed-Rank tests comparing no-go and go trials. The bivariate association between TF-theta and TF-delta was estimated using Spearman's rank-order correlation for both the grand average across trials and the difference scores between no-go and go component measures. Next, regression analyses were performed to assess whether the TF components contributed uniquely to, and accounted for, the time-domain N2 and P3 components. For each regression, theta and delta scores served as the predictor variables, with N2 and P3 alternately serving as the dependent variable. For two of the models, the overall grand average values were used for the time-domain component (i.e., N2 or P3) and the theta and delta scores, and for the remaining two, the no-go and go difference scores were used for both the ERP components and TF scores. Thus, the four models were: 1) the overall N2 peak as the dependent variable, and overall theta and delta measures as the predictors,
