Does changing social influence engender changes in alcohol intake? A meta-analysis.

Objective: Past research has suggested that social influences on drinking can be manipulated with subsequent reductions in alcohol intake. However, the experimental evidence for this and the best strategies to positively change these social influences have not been meta-analyzed. This research addressed these gaps. Method: Randomized controlled trials testing social influence-based interventions on adults' drinking were systematically reviewed and meta-analyzed. The behavior change techniques used in each study were coded and the effect sizes showing the impact of each intervention on (a) social influence and (b) alcohol intake were calculated. Metaregressions identified the association between these effect sizes, as well as the effect of specific behavior change techniques on social influences. Results: Forty-one studies comprising 17,445 participants were included. Changes in social influences were significantly associated with changes in alcohol intake. However, even moderate-to-large changes in social influences corresponded with only a small change in drinking behavior and changing social influences did not reduce alcohol-related problems. Providing normative information about others' behavior and experiences was the most effective technique to change social influences. Conclusions: Social influences and normative beliefs can be changed in drinkers, particularly by providing normative information about how much others' drink. However, even generating large changes in these constructs are likely to engender only small changes in alcohol intake.