In the present study, high-conflict (INCONG) stimuli evoked stronger theta power in ACC and fronto-parietal areas than other conditions under placebo. Conflict-related theta increase (defined as INCONG vs. CONG comparison) was observed only in the right ACC in the early time window (120–270 ms), suggesting its sensitivity to the early conflict detection stage. Evidence from studies using event-related potential (ERP) approach is broadly consistent with the timing of this difference, as it shows that the N2 component is sensitive to conflict [24], [44]. However, reports of alcohol’s effects on N2 during a flanker task are inconsistent [44], [45]. Because N2 and theta power are both clearly important for the early conflict detection stage, further studies are needed to resolve ACC’s contributions to these measures in the context of beverage effects on conflict-inducing conditions.
