Understanding the Mechanisms of Change in Social Norms around Tobacco Use: A Systematic Review and Meta-analysis of Interventions

"Social norms change interventions appear to be effective for reducing tobacco use and pro-tobacco social normative perceptions. In particular, leveraging role models appears to be the most effective social norms change mechanisms for tobacco control."

Tobacco use spreads through social networks, influencing social norms around tobacco use. Social norms are typically measured as individual perceptions of the prevalence of a behaviour ("descriptive norms") and the approval of that behaviour ("injunctive norms") within a specified group of influential individuals ("reference group"). This systematic review and meta-analysis not only examines social norms as a predictor of tobacco uptake but provides actionable guidance as to what social norms interventions are, how they work, and which types of mechanisms underlying interventions are most effective at reducing tobacco use.

The review process began with a search of Scopus, PubMed, PsycInfo, Clinicaltrials.gov, ProQuest Dissertations, the Cochrane Trial Registry, and the websites of the Society for Research on Nicotine and Tobacco, the Open Science Framework, medrXiv, and the Truth Initiative. The researchers sought experimental and quasi-experimental evaluation studies of interventions designed to shift tobacco use that noted social norms or social influence as part of the intervention design or set of measured variables. The included studies, which had to be written in English and had publication dates from database inception to May 30 2024, were analysed in a narrative synthesis. Those studies providing sufficient statistics for tobacco and social norms outcomes were included in meta-analyses, which were performed separately for tobacco outcomes and social norms outcomes.

Ninety-five studies met inclusion criteria for the narrative synthesis, 200 effect sizes from 86 studies were included in the tobacco outcomes meta-analysis, and 66 effect sizes from 29 studies were included in the social norms outcomes meta-analysis. Twenty-six countries were represented by the included studies. The majority of studies did not report a theory used to guide their conceptualisation of social norms or social influence. Among those that did, the most common was the theory of planned behaviour. The majority of studies came from peer-reviewed journals, used a randomised controlled trial (RCT) design, described school-based programmes, and focused on the prevention of tobacco initiation. 

Interventions were commonly conducted among adolescent students in classrooms through multicomponent education sessions delivered by trained classroom teachers and peers acting as role models, often coupled with regular "booster" sessions over time. These interventions modified school curricula to leverage social influence effects for creating a group-level anti-tobacco social norm. Programme components typically included formal presentations on module content, informal discussions with peers, interactive activities and games. A central purpose of these programmes was to instil self-efficacy to refuse offers of tobacco from peers and to reinforce non-smoking behaviour. Many of these programmes considered not just the school environment, but the home environment as well, and included components for parents and other family members.

Besides classroom-based interventions, a number of interventions included tailored counseling components for both adults and children, typically using motivational interviewing. Only a few interventions leveraged digital technologies to change social norms.

The results of the primary sample meta-analyses suggest a statistically significant effect of social norms interventions on changing tobacco use and social norms outcomes (g = 0.233, 95% confidence interval (CI) = 0.166-0.301, P < 0.001, and g = 0.292, 95% CI = 0.090-0.494, P = 0.007, respectively). For comparison, an average effect size of g = 0.233 is about four and a half times larger than the average effect of smoke-free legislation on risk of any cardiovascular event (odds ratio (OR) = 0.91 or g = −0.05), and just over a third larger than the average effect of receiving a text message intervention on continuous abstinence from smoking (OR = 1.37 or g = 0.17).

Among the social norms change mechanisms included, role models exhibited the largest effect (g = 0.308, standard error (SE) = 0.079, P < 0.001). In the multivariable model, three social norms change mechanisms were still statistically significantly related associated with effect size: correction of misperceptions (g = 0.197, SE = 0.092, P = 0.039), role models (g = 0.345, SE = 0.127, P = 0.013), and resistance skills training (g = 0.230, SE = 0.060, P < 0.001).

Thus, the "meta-analytic findings confirmed that social norms interventions are effective for changing tobacco use, as well as for changing social normative perceptions around tobacco use....[The] findings are significant for the development of more impactful tobacco control interventions that leverage social norms and social influence. They offer a more granular picture of how such interventions can be used beyond only correcting normative misperceptions, which has been the dominant approach in substance abuse prevention interventions..." 

The findings suggest that "leveraging role models to drive change in tobacco use is the most effective social norms change mechanism for reducing tobacco use. In practical terms, this suggests that tobacco control practitioners should focus on understanding and leveraging influential network actors within close-knit tobacco use networks for tobacco control programs. Based on findings that social norms tend to spread within small, bounded networks via sparse inter-network connecting bridges..., it is crucial to think of tobacco control as a network-level process rather than solely an individual one. This means that interventions should be delivered at a group-level, and ideally by influential similar others (peers), in combination with regular programming that reinforces intervention messaging."

In discussing the findings, the researchers note the review's identification of the power of the social inoculation approach, which was first formally advanced in the 1960s. The approach uses a medical analogy to suggest that, as with a virus, one can be inoculated against persuasive media and messaging by exposure to weakened forms of arguments. Social inoculation involves training in how to recognise various sources of peer pressure to use tobacco, along with practice and role-play of specific resistance techniques and counterarguments. If enough individuals are instilled with skills and attitudes through prior exposure to weakened forms of social pressure to use tobacco, a new norm may be formed against tobacco use. (Editor's note: For more on this topic, see this article on resisting harmful norms using social inoculation.) In this vein, the researchers recommend that:

• Correction of misperceptions and resistance skills training can be part of individual-level change mechanisms, complemented by leveraging role models at the community-level.
• Given the prominence of these interventions to combat misinformation, a similar approach can be used to counter messaging and normative pressure promoting tobacco use and new tobacco products.
• Given that pro-tobacco media and products can drive positive pro-tobacco social normative perceptions among adolescents and their peers, resistance skills training is particularly crucial to counter tobacco initiation among youth.

The researchers note that no studies located that met inclusion criteria for this review were conducted in Latin America or on the entire African continent. "Research on social norms interventions for tobacco control in these settings is urgently needed to provide more accurate recommendations for low- and middle-income countries, where 80% of the world's tobacco users reside..." The researchers also point out that several Latin American countries have a high smoking prevalence among women. In these settings, they urge that analyses be disaggregated by gender to understand whether the social norms change mechanisms identified in this review have differential gender effects.

In conclusion: "By explicitly integrating social norms change approaches for tobacco control into policies and programs, potent demand-side interventions can be refined and strengthened."