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.