ROLE OF FEEDBACK IN FORMATION OF ACUTE TOLERANCE TO ALCOHOL

Objective: The contributions of feedback to formation of acute ethanol tolerance were studied during performance of a task that allowed prac tice in the absence of feedback about performance accuracy. Method: Th e perceptual instability of the seen environment during head movement (apparent concomitant motion, ACM) and the vestibule-ocular reflex (VO R) were measured before and after alcohol ingestion. In separate condi tions, eight (six female) subjects were either deprived or not deprive d of normal vision of the laboratory during the portion of the experim ent following onset of alcohol ingestion. Results: Alcohol caused ACM in the direction opposite head rotation to increase in both sessions. The degree of ACM increase was greater during sessions in which visual feedback was prevented than in sessions in which subjects could see t he surroundings. The increase in ACM was accompanied by a decrease in gain of the VOR which was relatively larger in the no-feedback conditi on. In addition, ACM returned to normal (pre-alcohol ingestion) values more rapidly during sessions in which subjects received visual feedba ck. Conclusions: The results suggest that feedback is an important com ponent in forming acute tolerance to alcohol, independent of task prac tice.