At the end of each experimental session participants rated the beverage content, the perceived level of intoxication and task difficulty on Likert scales (1–5). Participants correctly perceived the beverage content under both alcohol (5.0 ± 0.2) and placebo (1.5 ± 0.9). On the scale from 1 (not at all) to 5 (very much), participants reported feeling moderately intoxicated (2.8 ± 0.7) under alcohol, but not at all intoxicated under placebo (1.0 ± 0.2), F(1,21) = 121.7, p < 0.001. Subjects estimated that the alcoholic beverage contained 2.4 ± 0.8 “alcoholic drinks,” a slight underestimate of the actual average amount containing 2.8 standard drinks defined as 1.5 fl oz of vodka. They also estimated that the placebo beverage contained 0.1 ± 0.4 “alcoholic drinks.” On the scale from 1 (easy) to 5 (difficult), subjects rated the task as being moderately easy (2.4 ± 1.2) but the perceived difficulty was not influenced by beverage. These results indicate that the participants were aware of the beverage contents. Even though previous balanced placebo studies indicate that ERPs and autonomic physiological measures are influenced only
