Pilot study
A pilot study (N=13 social drinkers) found surprising results (Figure
3). In this pilot study, participants discriminated normal trials (e.g.,
with black elements) from differently coloured oddballs (e.g., with
green elements). Participants completed the task twice, in separate
sessions on separate days (a standard procedure in alcohol research, see
Halsall et al. 2021 for meta-analysis). In one session they drank
0.65g/kg alcohol before EEG recording, in the other they drank an
equivalent placebo drink before EEG recording. Despite our
pre-registered predictions (https://aspredicted.org/xp4dd.pdf), alcohol
enhanced the SPN, particularly during later 400-1000 ms time window (t
(12) = -4.188, p < .001, dz = 1.161). This
suggests alcohol may disinhibit the visual cortex, making it more
sensitive to task-irrelevant symmetry. However, this unexpected result
required replication. The pilot study also found that alcohol had no
effect on the P1 peak (t (12) = -0.112, p = .913, dz =
0.031), and reduced N1 dip (t (12) = 4.460, p < .001,
dz = 1.237).