For the higher frequency data, two components were extracted based on the Scree test, both accounting for a total of 28.5% of variance in the decomposition (see Figures 2 and 3). PC1 occurred during the N2-P3 complex (~275 to 400 ms) in the theta range (3 to 5.5 Hz), and PC2 occurred earlier during the P2 ERP (~120 to 200 ms) and at a higher frequency than PC1 (~5 to 9 Hz). Of interest to the present study is PC1 (Theta) for the following reasons: 1) it exhibited an experimental difference (Wilcoxon Signed-Rank tests comparing activity in no-go vs. go trials: Zs = 6.136 and 0.208, ps < 0.001 and = 0.836 for PC1 and PC2, respectively), and 2) its time course corresponded best to the N2-P3 ERPs. Three PCs were extracted using the Scree test for the lower frequency data, accounting for a total of 93.6% of the variance in the data. PC1 and PC3 were maximal between 600 and 800 ms, and PC2 occurred during the N2-P3 components (~250 to 450 ms). PC2 (Delta) was chosen for further
