Perceived social norms and their relation to university student drinking.

Objective: The aims of this study were to compare university students' perceptions of drinking norms with actual student drinking norms, to examine the relationship between norm misperception and individual drinking status and to investigate the relative importance of three reference groups as potential determinants of individual drinking levels: young people in New Zealand of the same age and gender, local university students of the same age and gender and the closest friends of individual respondents.

Method: In 2002 a randomly selected representative sample of 1,564 New Zealand university students aged 16-29 years completed an Internet-based survey of their alcohol use (response rate: 82%). Respondents were asked to estimate the incidence of heavy episodic drinking and vomiting in the three reference groups and to rate their own drinking in comparison. Estimates within +/- 10% of actual norms were rated as accurate; estimates above or below actual norms by more than 10% were rated, respectively, as overestimates and underestimates.

Results: The vast majority of women (80%) and men (73%) overestimated the incidence of heavy drinking among student peers. The incidence of vomiting was also overestimated, but to a lesser extent. The extents of overestimation for both heavy drinking and vomiting were strongly related to the individual's heavy drinking frequency (p < .001). Only 9% of drinkers believed they drank more than other students. Correlations of perceived norms and self-reported drinking increased with the proximity of the social grouping to the individual and were higher for women than for men.

Conclusions: This New Zealand university sample showed strong evidence of norm misperceptions, consistent with the results of several U.S. studies. Perceived norms are strongly related to individual drinking levels. It is unclear whether norm misperceptions are a cause or effect of heavy drinking. Research in which norm misperceptions are corrected may assist in understanding their importance in the etiology and treatment of heavy drinking.