Control of alcohol tolerance by reinforcement in nonalcoholics

The development of tolerance to alcohol was examined in two experiments with nonalcoholic drinkers. In both experiments, male undergraduates received pretraining on a pursuit rotor task and were then randomly assigned to either alcohol or placebo conditions. In the first experiment, monetary and performance feedback reinforcement for pursuit rotor performance were provided to both groups over four drinking sessions. In the second experiment, two final drinking sessions were added where no reinforcement was provided to either the alcohol or placebo subjects, and an additional alcohol group received no reinforcement throughout the six drinking sessions. Tolerance to the impairing effects of alcohol on pursuit rotor performance developed only for the reinforced alcohol subjects; withdrawal of reinforcement from tolerant subjects resulted in a return of impaired performance, i.e. tolerance was extinguished. Impairment remained consistently high in the non-reinforced alcohol subjects throughout all six drinking sessions. The results provide support for the learning hypothesis of behavioural tolerance by demonstrating that its acquisition and extinction may be controlled by reinforcement.