Behavioural inhibition under alcohol, effects of reinforcement and the setting

Abstract

The present research measured the effect of alcohol on inhibitory control (using a go-stop task) when two environmental factors, setting and reinforcement, were manipulated. Administering alcohol in a novel setting, or providing immediate positive reinforcement of inhibitions was predicted to counteract the impairing effect of alcohol on inhibitory control. Seventy-two male social drinkers were randomly assigned to one of eight treatment groups (n=9). Four groups were tested during their first visit to the laboratory (novel setting) whereas the remainder were tested after one drug-free exposure to the laboratory (familiar setting). In Phase 1 of the research, two groups in each setting received alcohol (.62 g/kg) or a placebo and performed the go-stop task with no consequences for task performance. The results showed that the administration of alcohol in a familiar setting impairing inhibitions, whereas alcohol in the novel setting had no significant effect on inhibitions. Furthermore, the setting had no effect on the response inhibitions of groups that expected alcohol but received a placebo. In Phase 2 of the research, three pairs of groups received alcohol and performed the task with either immediate positive reinforcement, or a monetary incentive, or no consequence for inhibitions. In accordance with the hypothesis, the impairing effect of alcohol in the familiar setting was reduced only when immediate positive reinforcement was administered. In contrast, in the novel setting, all groups showed little change from drug-free levels of inhibitory control. No systematic changes in response reaction time (RT) in any of the groups could account for these findings. This research provides the first experimental evidence to show that the effects of alcohol and of reinforcement on inhibitory control of behaviour depend on the novelty-familiarity dimension of the setting. Moreover, the results indicate that a loss of inhibitory control is not an inevitable effect of a moderate dose of alcohol.