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).