Category Archives: behaviour

Better measuring of social norms in adolescents’ food choices (or an initial attempt thereof)

by Viviana Albani

A recent review of social norms and eating behaviour concluded that “normative social influence on eating is potent and pervasive”[1]. Social eating norms constitute implicit rules about appropriate eating behaviour in a group and are thought to influence food choice and consumption through interlinked processes of motivations for affiliation and acceptance, informational functions about the right amounts to consume and the right foods to eat, and social identification with a specific group[1, 2]. Two types of norms are broadly recognised, descriptive norms – what others do, and injunctive norms –what others think. The effect of descriptive and injunctive norms on eating behaviour has been demonstrated in adults and in children in multiple studies using experimental manipulations of the social eating environment[2]. For schoolchildren, although the strength of social influence on food choice has been found to vary according to context (age of the child, type of food), there is growing consensus that peers exert influence on their food choice, to the point that it can be hard to get children to revert to a desirable behaviour after an initial negative peer influence[3, 4]. For adolescents in particular, peer group norms may be especially important because during this period peers are a salient reference group and teens experience a more intense need for peer approval and group acceptance.

At the same time, when asked what others eat and their attitudes to healthy eating, adolescents have been found to be overly pessimistic about the extent to which their peers engage in unhealthy food choices and about how widespread negative attitudes towards healthy foods are[5, 6]. In practice, this may mean that this age group may be choosing less healthy diets than those that would be really `required’ (in the sense of group norms) by their peers. This was the conclusion of a study looking at soft drink and fruit and vegetable intakes among children of the same school class[5]. These results are tantalising because, from a policy perspective, they suggest that better information about what peers actually do and think –lowering the social pressure to conform- could improve adolescents’ choices. It is important then to correctly identify these norms in order to design effective interventions that tackle potential misperceptions and channel healthier choices.

Studies that have looked into identifying food peer norms have used surveys to ask children about their own opinions and behaviours and the opinions and behaviours of their peers in a group, such as a class room[5, 7-9], and from there estimated the perceptions of others’ beliefs and the prevalence of an opinion or behaviour. This approach has two important drawbacks, however. One is operational, questions about what others do or think typically have large non-response rates. One high-quality study reported up to 50% missing responses[5]. I have been somewhat more successful in my own work on fruit and vegetable intake, with 30% missing responses. The other is more fundamental; although calculating the average or the mode over individual responses provides a description of what may be unpopular in a group, in other words, the collection of private beliefs, this alone does not constitute a social norm, which by definition is a shared standard.

The above point is emphasised by Professor Cristina Bicchieri[10], who distinguishes between what may be seen as unpopular, and the special characteristic of social norms that combine unpopularity with the perception of social disapproval/approval. In other words, a particular food may be unpopular in a group, but this just reflects a preference that is frequent in a group; whereas the existence of a norm implies that a choice is disapproved of because it is expected that others will disapprove. In this context, Bicchieri proposes the use of game theoretic approaches to identifying the existence of social norms in a wide range of behaviours such as binge drinking. One particular design from experimental economics relevant for identifying group norms is a coordination game used in a norm-elicitation task[11]. This was the approach used in a recent study led by Nick Bardsley of the University of Reading in which I had the opportunity to contribute. Social norms were identified as the mode of responses to the norm-elicitation task and used to explore the existence of pluralistic ignorance, which is the situation where individuals believe that their own behaviour is driven by social pressure but that of others reflects their acceptance of the norm[12, 13]. Correcting pluralistic ignorance constitutes the essence of changing misperceptions of peer norms and the social spread of healthier behaviours that are privately more preferred by adolescents.

Variants of this norm-elicitation task have been applied in other areas of economics[14], but it has yet to have a wider uptake amongst researchers studying the impact of perceptions of social norms on healthy eating and other health behaviours of adolescents. Although the method imposes additional costs to studies that may already be large and complex to undertake, the potential benefits from increased validity in the measurement of peer group norms should not be underestimated when informing interventions and policies to tackle the challenge of encouraging adolescents to make healthier food choices.

  1. Higgs, S., Social norms and their influence on eating behaviours. Appetite, 2015. 86: p. 38-44.
  2. Robinson, E., et al., What Everyone Else Is Eating: A Systematic Review and Meta-Analysis of the Effect of Informational Eating Norms on Eating Behavior. Journal of the Academy of Nutrition and Dietetics, 2014. 114(3): p. 414-429.
  3. Greenhalgh, J., et al., Positive- and negative peer modelling effects on young children’s consumption of novel blue foods. Appetite, 2009. 52(3): p. 646-653.
  4. Houldcroft, L., E. Haycraft, and C. Farrow, Peer and Friend Influences on Children’s Eating. Social Development, 2014. 23(1): p. 19-40.
  5. Lally, P., N. Bartle, and J. Wardle, Social norms and diet in adolescents. Appetite, 2011. 57(3): p. 623-627.
  6. Perkins, J.M., H.W. Perkins, and D.W. Craig, Misperceptions of Peer Norms as a Risk Factor for Sugar-Sweetened Beverage Consumption among Secondary School Students. Journal of the American Dietetic Association, 2010. 110(12): p. 1916-1921.
  7. Di Noia, J. and K.W. Cullen, Fruit and Vegetable Attitudes, Norms, and Intake in Low-Income Youth. Health Education and Behavior, 2015. 42(6): p. 775-782.
  8. Stok, F.M., et al., Don’t tell me what I should do, but what others do: The influence of descriptive and injunctive peer norms on fruit consumption in adolescents. British Journal of Health Psychology, 2014. 19(1): p. 52-64.
  9. Stok, F.M., et al., The proof is in the eating: Subjective peer norms are associated with adolescents’ eating behaviour. Public Health Nutrition, 2014. 18(6): p. 1044-1051.
  10. Bicchieri, C., The Grammar of Society: the Nature and Dynamics of Social Norms. 2006, Cambridge: Cambridge University Press.
  11. Krupka, E.L. and R.A. Weber, IDENTIFYING SOCIAL NORMS USING COORDINATION GAMES: WHY DOES DICTATOR GAME SHARING VARY? Journal of the European Economic Association, 2013. 11(3): p. 495-524.
  12. Miller, D.T. and C. McFarland, When social comparison goes awry: The case of pluralistic ignorance, in Social comparison: Contemporary theory and research, J. Suls and T.A. Wills, Editors. 1991, Lawrence Erlbaum Associates: Hillsdale, NJ.
  13. Miller, D.T. and L.D. Nelson, Seeing approach motivation in the avoidance behavior of others: implications for an understanding of pluralistic ignorance. Journal of Personality and Social Psychology, 2002. 83(5): p. 1066.
  14. Erkut, H., D. Nosenzo, and M. Sefton, Identifying social norms using coordination games: Spectators vs. stakeholders. Economics Letters, 2015. 130: p. 28-31.