Blood alcohol level discrimination. The effects of family history of alcoholism, drinking pattern, and tolerance.

Alcoholics seem less able than nonalcoholics to maintain blood alcohol level (BAL) estimation accuracy after discrimination training focused on changes in internal sensations during intoxication. To identify factors associated with this phenomenon, nonalcoholic subjects participated in an experiment that examined the effects of family history of alcoholism, drinking pattern, and behavioral tolerance to alcohol on BAL discrimination. Blood alcohol level estimates were made during baseline, training, and posttraining sessions. Groups of subjects differing in family history or drinking pattern did not differ in BAL estimation accuracy. "Low tolerant" subjects, however, were substantially more accurate than "high tolerant" subjects in posttraining BAL estimation. This finding suggests that the development of tolerance may relate to the inability to discriminate BAL, a finding which, if confirmed, has important causal and treatment implications.