P300
P300 results are shown in Figure 8. In the Oddball task, the expected P300 effect was found at posterior central electrodes (P1, Pz and P2). This was apparently larger in the alcohol than placebo condition. There was no P300 in the Regularity task. Mixed ANOVA found main effect of Task (F (1,50) = 10.383, p < .001, ηp2 = 0.172) and Task X Drink interaction (F (1,50) = 5.037, p = .029, ηp2 = 0.092). Additional analysis found no main effects or interactions involving Oddball colour (largest effect, F (1,47) = 1.128, p = .294, ηp2 = 0.023).
In the Oddball Task, the apparent difference between alcohol and placebo conditions was not significant (t (25) = 1.884, p = .071), although the P300 was present in the placebo condition (t (25) = 4.458, p < .001, dz = 0.874), but not alcohol condition (t (25) = 1.536, p = .137, dz = 0.301). Bayesian analysis was not conclusive here, and only confirmed the presence of a main effect of Task on P300 (BF include > 5).