Evidence that expectancies mediate behavioral impairment under alcohol

This research tested the hypothesis that social drinkers challenged to expect intense impairment from alcohol will display reduced behavioral impairment under the drug and that the influence of this expectancy challenge diminishes as a function of prior drinking experience.

Male social drinkers (N = 66) were assigned to one of three equal-sized groups (A, AC, and NT). All subjects were trained on a psychomotor task. They then completed a rating scale which showed that they expected alcohol to mildly impair their task performance. After training, Group A received a moderate dose of alcohol (0.56 g/kg) and performed the task. Group AC received the same dose and, prior to performing the task, their expectancies were challenged by new contradictory information indicating that alcohol would cause intense impairment. Group NT served as a no-treatment control and received no alcohol and no information to challenge their expectancies prior to performing the task.

Alcohol impaired performance and, consistent with the hypothesis, Group AC displayed less impairment compared to Group A. In addition, the influence of challenging expectancies diminished in the AC group as a function of the duration of drinking experience, with the more experienced drinkers being less affected by the expectancy challenge and displaying more impairment.

The study demonstrates that alcohol-related expectancies concerning impairment may mediate the behavioral effect of alcohol and indicates that individual differences in the duration of drinking experience may influence the case of challenging or manipulating these expectancies.