P1 and N1
Unlike the pilot study, the P1 peak was slightly enhanced by alcohol (red waves) compared to placebo (green waves). This was confirmed a main effect of Drink (F (1,50) = 5.368, p = .025, ηp2 = 0.097). There was no main effect of Regularity or Task, and no interactions (largest effect p = .262). Bayesian ANOVA analysis confirmed the absence of these effects (BF include < 1/3) but could not confirm the presence of an effect of Drink (BF include approximately 1). Therefore, we do not overinterpret the small and unexpected effect of alcohol on P1 peak.
The N1 drop was larger in the Symmetry than Random conditions, and larger in the Placebo the alcohol conditions. N1 effects were similar in both tasks. This was confirmed by main effects of Regularity (F (1,50) = 38.032, p < .001, ηp2 = 0.432) and Drink (F (1,50) = 53.572, p < .001, ηp2 = 0.517). The Drink X Task interaction was not significant (F (1,50) = 3.663, p = .061, ηp2 = 0.068), and there were no other main effects or interactions (largest effect p = .413). Bayesian ANOVA analysis supported the presence of Drink and Regularity effects (BF include > 100). However, it did not consistently support the absence of most other effects and interactions.