Interference of expectancy and attention demanding tasks on alcohol intoxication

Seventy-nine undergraduate social drinkers were the subjects in two studies. Both studies had two experimental sessions and followed a blind design. The subjects in experiment I (expectancy manipulation) were informed they would certainly receive an alcoholic beverage in one session, while in the other one they were told the beverage possibly contained alcohol. Thus, the different expectancy on the beverage content was evaluated. The volunteers in experiment II (attention demanding tasks) were submitted to attention tests in one session and in another one they were not. Thus, the assumption that tasks would motivate the subjects to stay more sober and rate themselves as less intoxicated was studied. Each subject received one of three alcohol doses (0.0; 0.4 or 0.6 g/kg): the same dose in both sessions of each experiment. Blood alcohol level (BAL), reaction time, and self-rating intoxication scores were recorded. The variables studied did not alter either BAL or reaction time values. The expectancy manipulation changed the self-rated intoxication with the lower alcohol dose (0.4 g/kg). So when doubt had been raised the subjects rated themselves as less intoxicated. However, this change was only found with a verbal scale. The attention demanding tasks manipulation did not change the self-rating evaluations. It is suggested that the tasks performed were not appropriate to motivate the subjects to stay sober. The differential sensitivity of the self-rating intoxication scales utilized, and the role of alcohol dose in the study of nonpharmacological variables are discussed.