The social norms approach, which communicates the accurate, positive norms already existent in populations, has proven effective in reducing the commonly held myths and misperceptions that contribute to risky behavior, and thus has led to reductions in risky behavior itself.

Although there is compelling data about the efficacy of this strategy, most social norms interventions have targeted discrete, confined populations such as students at public schools or on college campuses. Additionally, most have taken the form of case studies, which lack matched control sites that can strengthen conclusions regarding program impact.

The project described in this report is titled the MOST of Us Prevent Drinking and Driving campaign. It was the first demonstration applying social norms theory to the problem of impaired driving in a large statewide population. This controlled social norms intervention was designed to reduce risky driving after drinking behavior among Montana's young adults ages 21 to 34, a group that has been over-represented in alcohol-related crashes statewide. An initial campaign survey found that while only 20.4 percent of Montana young adults reported having driven within one hour of consuming two or more drinks in the previous month, 92 percent of respondents perceived that the majority of their peers had done so. Such a disparity between perception and behavior is precisely what social norms theory predicts, and by correcting this misperception, the MOST of Us Prevent Drinking and Driving campaign was able to reduce the prevalence of reported driving after drinking in its target population.

With funding from the National Highway Traffic Safety Administration (NHTSA) and the Montana Department of Transportation (MDT), a 15-month media campaign was carried out in a 15-county intervention area in the western portion of Montana. This intervention area is home to half of the State's 21-to-34-year-old population. This quasi-experimental intervention exposed the selected counties to high doses of the social norms message, and then compared the resulting changes in perceptions, attitudes, and behaviors with the eastern Montana counties that served as the control group. The treatment counties were dosed with high-intensity, paid social norms radio and television commercials, theater slides, posters, billboards, local and college newspaper advertisements, and promotional items bearing social norms messages. A low-dosage control area in the eastern half of the State was exposed to low levels of free media, local and college newspaper advertisements, and promotional items. These campaign media in both the high- and low-dosage areas communicated the normative message that MOST Montana Young Adults (4 out of 5) Don't Drink and Drive. Additional messages focused on the use of designated drivers and other protective factors, and some were tailored to particular markets with county-specific statistics.

According to social norms theory, fear-based media efforts can compete with positive social norms messages by solidifying already-exaggerated misperceptions about the prevalence of impaired driving. For this reason, specific controls were used to eliminate or severely restrict the use of fear-based media efforts in the treatment counties. The non-targeted counties across the remainder of the State were allowed to operate with traditional fear-based campaign themes.

A baseline and three follow-up surveys were conducted at various points before, during, and after the campaign. In each survey, representative samples of respondents in both the treatment and control areas were asked identical questions about their attitudes and behaviors about impaired driving, as well as questions about their perceptions of the norms for these attitudes and behaviors among their peers. Analysis of this self-reported data showed unequivocally that the high-intensity social norms campaign improved the accuracy of the target audience's perceived norms and increased its healthy, preventative attitudes and reported behaviors regarding impaired driving. Compared to data from the control counties, statistically significant results among young adults in the targeted counties showed:

• a 24.8-percent relative increase in recall of campaign messages about the majority norms regarding not driving while impaired;
  
  
• a 7.5-percent relative decrease in the percentage that believed the average Montanan their age drove after drinking during the previous month;
  
  
• an 11.0-percent relative increase in the percentage that accurately perceived the majority of their peers use a non-drinking designated driver;
  
  
• a 13.7-percent relative decrease in the percentage that reported personally driving after drinking;
  
  
• a 15.0-percent relative increase in the percentage that reported always using non-drinking designated drivers;
  
  
• a 16.5-percent relative increase in the percentage who would support passing a law to decrease the BAC legal limit for driving to .08 from .10.

By the end of the campaign, young adults in the intervention counties were seeing the normative environment more accurately in comparison to their counterparts in the control counties. The correction of their misperceptions about the pervasiveness of driving after drinking among their peers led to positive changes in their personal attitudes and to a reduction in reported frequency of risky behaviors. In contrast, young adults residing in the control counties who were exposed to the traditional fear-based messages reported increased risks associated with impaired driving.

This research provides practical implications for traffic safety programmers and signals the need for future research on the behavior-changing potential of promoting positive norms.