Alcohol, cognitive impairment and expectancies

Objective: This experiment tested the hypothesis that differences in subjects' expectations about the impairing effect of alcohol on cognitive performance predict their responses to alcohol and to a placebo. Method: Twenty-seven male social drinkers were randomly assigned to one of three treatment groups: alcohol (0.62 g/kg), placebo, or no treatment control. All groups practiced a Rapid Information Processing Task that measured cognitive performance by the speed of information processed. After practice, they rated the degree of impairment they expected alcohol to have on their performance, and then performed the task under their different treatments. Results: Alcohol slowed (i.e., impaired) information processing compared with placebo and no treatment. In addition, those who expected more impairment performed more poorly under alcohol, and under the placebo when alcohol was expected. When no beverage was received, no expectancy-performance relationship was obtained. Conclusions: The findings call attention to expectancies as an important factor that may contribute to individual differences in cognitive functioning under alcohol and placebo.