Expectancies about alcohol-induced motor impairment predict individual differences in responses to alcohol and placebo

Objective: Two experiments were designed to test the hypothesis that the amount of alcohol-induced impairment that a drinker expects will predict his response to alcohol and to placebo. Method: Social drinkers (N = 81) were familiarized with a laboratory motor skill task before they rated the amount of impairment on the task that they expected from a moderate dose of alcohol. The degree of change in the subjects' performance was measured during an alcohol session and a subsequent session where alcohol was expected but a placebo was received. Results: Subjects who expected greater impairment displayed poorer performance under alcohol (0.35 g/kg) and under placebo. Conclusion: This evidence calls attention to the importance of expectancies as a factor that may contribute to the understanding of individual differences in behavior under alcohol and a placebo.