Response expectancies affect the acquisition and display of behavioral tolerance to alcohol.

Two experiments demonstrated that a learned expectation of a favourable consequence for drug-compensatory performance enhanced behavioral tolerance to alcohol, and when the expectancy was trained, the subsequent display of tolerance depended upon its consequence. Both experiments involved each of four groups of six male social drinkers each, who drank 0.62 g/kg alcohol on four sessions, and a placebo on a fifth session. Experiment 1 provided two groups with the opportunity to learn the response expectancy by performing a motor task under alcohol with either an informative consequence (IO) or information plus money contingent upon drug-compensatory performance (MI). Two control groups performed with either no outcome (N), or with money for compensatory performance but no information about earnings until the experiment concluded (MO). The effects of learning history were evident on sessions 4 and 5 when the same consequence was contingent upon the performance of all groups. Compared to controls, the groups that had received response expectancy training (MI and IO) displayed significantly more alcohol tolerance and greater compensatory facilitation of performance under placebo. In Experiment 2, all groups received the same response expectancy training, and the effect of the consequence of compensatory performance was demonstrated during subsequent test sessions 4 and 5. An informative consequence (MI or IO) enhanced tolerance and the compensatory response to placebo, whereas performance with no response contingent information (N or MO), revealed little tolerance or compensatory response to placebo. Theoretical and practical implications of the findings were discussed.