Scientists show that peer influence can be as effective as expert advice

Eating habits can be shaped not only by the authority of medical experts but also through ordinary conversations among friends. Researchers at HSE University have shown that advice from peers to reduce sugar consumption is just as effective as advice from experts. The study's findings have been published in Frontiers in Nutrition.

Excessive sugar consumption has become one of the major public health concerns worldwide. According to the World Health Organization, one in eight people globally lives with obesity, and many more are overweight. High intake of sugary foods contributes to an unbalanced diet and increases the risk of developing diabetes, tooth decay, atherosclerosis, cardiovascular disease, and other non-communicable conditions.

As a rule, campaigns promoting healthy eating rely on the authority of experts such as physicians and nutritionists. Scientists set out to determine whether advice from ordinary people—friends and peers—could be just as effective. Researchers at the HSE Institute for Cognitive Neuroscience conducted an experiment involving 88 young adults who answered questions about their consumer behaviour. Participants were randomly assigned to three groups and exposed to different types of messages. The first group listened to a lecture by a nutrition expert on the risks of sugar consumption; the second heard a monologue by a university student presenting the same arguments; and the third listened to a discussion among three students expressing different viewpoints. Before and after the intervention, participants indicated—using an auction-based method—the maximum amount they were willing to pay for various products, including those high in sugar. This approach allowed the researchers to assess participants’ actual intentions rather than self-reported attitudes.

The results showed that all three types of interventions significantly reduced participants’ willingness to pay for sugary products. The key finding was that no statistically significant differences were found between the groups, indicating that peer recommendations were just as effective as expert advice.

'In earlier studies, we demonstrated how expert persuasion can influence consumers' decision-making. In this study, for the first time, we show that adults are equally susceptible to both forms of influence—expert and peer endorsement. This may be because adults tend to be more autonomous from authority figures and are more strongly guided by the social norms of their referent group,' notes Nina Arzumanyan, Research Assistant at the International Laboratory of Social Neurobiology of the HSE Institute for Cognitive Neuroscience and first author of the study.

When communicating with peers, identification processes are activated, leading individuals to adopt others’ attitudes in order to maintain relationships within their referent group or because such behaviour aligns with their own value system.

'Using peer persuasion may be a more accessible and scalable approach than relying on experts. People tend to trust those who are similar to them and share comparable life experiences,' comments Anna Shestakova, Director of the Centre for Cognition and Decision Making at the HSE Institute for Cognitive Neuroscience and co-author of the study.

In future work, the researchers plan to investigate the neurocognitive mechanisms underlying the influence of experts and peers on eating behaviour. This research will help clarify why different forms of social influence produce similar outcomes and how interventions aimed at promoting healthy eating habits can be made more effective.