There were substantial normative misperceptions in this general population sample of problem drinkers. Participants overestimated the proportion of Canadians who drank more than they do and who drank more than seven drinks per week by more than double the actual proportion of Canadians who drank more than they did. The magnitude of discrepancy is comparable with findings consistently reported in the college student literature (Neighbors et al., 2006
). In contrast, the perception of the proportion of Canadians who were abstinent was fairly accurate. This finding is in sharp contrast with normative misperceptions for smokers where a general population sample of Canadian smokers overestimated the proportion of Canadian smokers by 20% (Cunningham and Selby, 2007
). It is possible that some of this difference could be due to variations in the way the question was asked—smokers were asked to estimate the percent of Canadians their own age and sex who smoked, while drinkers in the present study were asked to estimate the percent of people their own sex who did not drink at all. However, it is difficult to imagine that the degree of difference was solely due to this difference in wording, pointing to a potentially interesting contrast in normative misperceptions between smokers and drinkers that merits further examination.
As predicted, there was a statistically significant association between severity of the persons' own drinking and the extent to which drinking norms were overestimated. These correlations were relatively small, however, indicating that this is not a powerful relationship. One limitation to generalizing these results to the general population of all alcohol drinkers is that the sample was restricted to problem drinkers (i.e. those with an AUDIT score of 8 or more). Although this is a liberal definition of problem drinking, restricting the sample in this manner could have led to reductions in the observed relationship between severity of alcohol consumption and levels of normative misperceptions.
There was only limited evidence of an association between the participants' age and their estimates of how much others drink. One limitation of this finding was that participants' estimates of how much other Canadians drink was not age specific. As was mentioned earlier, in the related research with smokers, where age was strongly associated with normative misperceptions, smokers were asked to estimate the percent of Canadians their age and sex who smoked (as opposed to the present study where participants were just asked how much Canadians of their same sex drank, Cunningham and Selby, 2007
). Although this difference was intentional because age-independent norms were the most relevant for the larger intervention trial of which this survey is a part (Cunningham et al., 2008
), it is possible that the relationship between norms and age exists only with normative misperceptions about the proportion of people one's own age who drink (or smoke).
Another issue to consider with normative misperception research to-date is the assumption that comparison data of general population drinking such as were used here are the gold standard. Self-reported drinking on these population surveys under-reports the actual amount of alcohol consumed (when compared with alcohol sales data generated estimates of per capita consumption, Stockwell et al., 2004
). Thus, it is possible that the extent of normative misperception reported in the present (and other) studies are in fact overestimates of the extent to which heavy drinkers overestimate how much others drink.
Despite our uncertainty about the accuracy of general population comparison data, there probably still exists some level of normative misperception, particularly among heavier drinkers, if for no other reason than their tendency to spend time with other heavier drinkers. Irrespective of the actual degree of accuracy of population norms data, interventions targeting normative misperceptions might be useful in general population samples as they have proved to be among college students. Some research already demonstrates that brief interventions targeting normative misperceptions in general population samples have an impact (Cunningham et al., 2001
; Wild et al., 2007
; Cunningham et al., 2009
). However, to date, these studies have not tested whether the impact of these brief interventions is actually mediated by reductions in normative misperceptions among those who reduce their drinking. Nevertheless, further research in this area would appear to be warranted, both to increase our understanding of why (and how much) heavy drinkers overestimate other's drinking and to explore whether correcting these misperceptions is an active ingredient in motivating change from problem drinking.