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A social norms approach to encouraging healthier eating Suzanne Higgs School of Psychology University of Birmingham, UK.

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Presentation on theme: "A social norms approach to encouraging healthier eating Suzanne Higgs School of Psychology University of Birmingham, UK."— Presentation transcript:

1 A social norms approach to encouraging healthier eating Suzanne Higgs School of Psychology University of Birmingham, UK

2 We are encouraged to eat healthily

3 What is the evidence this works? Public information campaigns and educational measures (Capacci et al. 2012) Strong evidence on awareness/attitudes Small impact on behaviours Health message and labelling at point of purchase (Skov et al. 2013) Outcomes not consistent Labelling foods as ‘healthy’ has been associated with being less tasty


5 Alternative approaches are needed

6 Obesity spreads though social ties Chistakis and Fowler (2007) Framingham Heart Study 5124 subjects 12,067 in social network Longitudinal Social network mapped/modeled Increased chance of becoming obese: 57% if friend became obese 40% if sibling became obese 37% if spouse became obese

7 Eating is a social activity

8 Social influences on eating are powerful Goldman, Herman and Polivy, 1991

9 Social processes and eating Modelling Imitate others to make a good impression and be liked (Roth et al. 2001) Perceived norms The behaviour of others is a signal for appropriate behaviour (Cialdini 1988)

10 Modelling and impression management More modelling in unsociable versus sociable context (Hermans et al. 2009) Women eat lightly with an attractive man (Mori et al. 1987)

11 Modelling and impression management 50 female students mean age = 19.1 years, s.d = 1.0 healthy BMI 21.1, s.d = 2.6 Manipulation: Priming of social acceptance Word search involving social acceptance or neutral words (Carvallo & Pelham 2006) Social interaction with a confederate who ate 16 pieces of popcorn

12 Participant characteristics and food intake Primed condition (n = 25) Neutral condition (n = 22) BMI21.1 (2.7)21.1 (2.4) Hunger (0–10 cm scale) 4.8 (2.4)4.2 (2.8) Restraint (0–21 scale) 7.8 (5.3)7.0 (5.4) Degree of matching to confederate 5.32 (8.4)−0.59 (9.6)* Robinson et al. 2011

13 Modelling and food choice 105 female students mean age = 19.9 years, s.d = 2.6 healthy BMI 21.9 s.d = 3.3 Buffet lunch (mood and food study): sandwich, pastries, crisps, Carrot sticks, Cherry tomatoes and rice cakes Manipulation: “Healthy” confederate “Unhealthy” confederate Choose alone

14 Method On arrival participants waited alone (control condition) or with a confederate who was instructed to arrive in waiting room 5 minutes early Baseline hunger and personality measures completed together Shown to buffet and asked to select a lunch Confederate makes choices seen by the participant Confederate and participant led to separate rooms to eat lunch Participant rates enjoyment of lunch items, completes restraint scale, asked to guess aims and has weight and height measured

15 Results: Participant characteristics ConditionControlHealthy Confederate Unhealthy Confederate Age (years)20.7 (0.5)19.7 (0.5)19.4 (0.4) BMI21.9 (0.6)21.7 (0.6)22.2 (0.6) Restraint7.1 (1.0)7.5(0.9)8.3 (0.9) Baseline Hunger (0-10 cm) 6.6 (0.4)5.8 (0.3)5.9 (0.3) Total calorie intake at buffet 243.8 (16.8)237.8 (15.7)249.7 (15.3) Robinson et al. British Journal of Nutrition 2013

16 Results: food choice Robinson et al. British Journal of Nutrition 2013

17 Discussion Choice of low energy sense foods was reduced when there was an “unhealthy” confederate present Suggests that participants were willing to consume low energy dense food but this was abandoned in the presence of an “unhealthy” confederate Unhealthy eating models may undermine attempts to increase or maintain consumption of low energy dense foods


19 Conclusions 1 Food intake and choice are influenced by social context at the time of eating/choosing Impression management is one process that may mediate the effects of social context on intake Friendship networks may be harnessed to promote healthier eating

20 Perceived norms People tend to use the behaviour of others to guide behaviour Norm effects are observed even when individuals believe they are not being watched Robinson et al. Appetite 2013






26 Social norms approach to behaviour change A participatory process Is not moralistic in tone Does not use scare tactics (McAlaney et al., 2010) Messages included in a social norms intervention present information about healthy norms of a population back to that population

27 Social norms approach to healthy eating campaigns

28 1) Meet experimenter 1. Complete demographics and given flyer and poster 2) Read posters and flyers 3) Rate flyer and poster for clarity etc. 4) Taken to new room and meet experimenter 2 5) Complete mood ratings, including hunger 6) Taken to buffet, select food and eat alone 7) Mood ratings, restraint scale, guess aims of study, weight and height 8) Measurement of habitual vegetable intake (how many portions of veg did you eat yesterday) and manipulation check


30 A social norm increases vegetable intake in low consumers * Robinson et al. in press, Health Psychology

31 A social norm increases fruit and vegetable intake in low consumers * Robinson et al. in press, Health Psychology

32 * *


34 What are the mechanisms? Correction of misperceptions? Conformation to expected behaviour? Change in expected liking and actual liking?

35 Medial orbitofrontal cortex activation

36 Expose participants to social information about liking for orange juice Neutral or negative information from an in-group (female university students) Negative information from an out-group (overweight male university students)

37 1) Rate other students’ liking for orange juice 2) Read survey results of liking for orange juice Negative in-group condition 3) Rate how much other students like orange juice (manipulation check) 4) mock personality measures 6) Asked to complete questionnaire for a different study 7) Rate liking for 6 foods including orange juice and apple juice 8) Write down aims and debrief Neutral in-group condition Negative out-group condition

38 Liking ratings: 0-10 cm line scale, anchors ‘don’t like at all’ and ‘like very much’ Neutral in-group condition, n = 28 Negative in-group condition, n = 27 Negative out-group condition, n = 29 Change in beliefs about other students’ orange juice liking - 0.2 (0.9) -3.6 (2.0) -3.0 (2.4) Self-beliefs about orange juice liking 7.3 (2.3) 6.0 (2.7)* 7.6 (2.3) Self-beliefs about apple juice liking 6.4 (2.6)6.4 (3.1)7.0 (2.7)

39 Conclusions 2 Perceived social norms can affect food choice and intake One underlying mechanism may be an effect on liking expectations

40 Current work Can “liking norms” be exploited to improve food choice? How long lasting are the effects of norms? Do the effects work in a real world context? Are they effective for different types of consumers?

41 Overall conclusions Social context is a powerful influence on food intake and choice Interventions that are based on social influences could be effective in improving dietary habits

42 Acknowledgements Collaborators: Paul Aveyard Oxford University Eric Robinson, Liverpool University, Peter Herman Toronto University

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