The trial-averaged time–frequency–space characteristics of the data provide a useful comparison for the results from the single-trial analyses. In general, the task elicited increased theta-band activity over medial frontal electrodes, centered around FCz, and maximal just prior to the response (Figure 2A). Although theta and delta power were significantly increased during all trials compared to baseline (Figure 2C), there was no significant main effect of current trial conflict, nor was there a significant previous × current trial conflict interaction (2 × 2 repeated-measures ANOVA: all p's > 0.05). Inter-trial phase coherence (the consistency of frequency band-specific phase angles across trials) showed low-frequency phase coherence and no clear medial frontal spatial focus (Figures 2B,D).
