Frequentist analysis
P1 peak and N1 drop effects were analysed with separate mixed ANOVAs.
These had two within subjects’ factors [Regularity (symmetry, random)
X Block (alcohol, placebo)], and one between subject’s factor [Task
(Oddball, Regularity)]. The SPN was first computed as a difference
between symmetry and random in two separate time windows. This was
analysed with mixed ANOVA [Interval (early, late) X Block (alcohol,
placebo)], and one between subject’s factor [Task (Oddball,
Regularity)]. The presence of an SPN in all windows was confirmed with
one sample t tests (symmetry – random < 0).