The main effect of group was not statistically significant [F (1, 59) = 2.83, p = 0.10]. Importantly, we observed a significant interaction effect of group and feedback valence [F (1, 59) = 6.16, p < 0.05]. Although there were no P300 amplitude differences between the alcohol and placebo group in response to positive feedback (18.0 μV versus 19.1 μV, p = 0.54), post hoc analyses revealed that, in response to negative feedback, alcohol-intoxicated individuals showed significantly reduced P300 amplitudes as compared to sober controls (22.1 μV versus 27.4 μV, p = 0.02), indicating a reduced sensitivity for negative feedback in alcohol-intoxicated subjects.
