Eat as they eat, not as they think. Descriptive but not injunctive social norm messages can increase fruit and vegetable intake

Abstract

Social norms influence food choice and intake and could be exploited to promote healthier eating. Here we test the effect of two types of social norm messages on consumption of fruit and vegetables (FV) in low and high consumers of fruit and vegetables. Young adults ( n = 75) read a poster that either (1) stated that other young adults regularly eat FV (descriptive social norm) or (2) stated that other young adults approve of regularly eating FV (injunctive social norm) or (3) outlined the health benefits of eating FV (control condition). Shortly after reading the poster participants were offered a snack including FV. Choice and intake were measured covertly. In habitually low consumers of FV, fruit and vegetable selection and intake was higher after reading a descriptive norm poster than after reading about the health benefits of eating FV. However, participants viewing an injunctive norm poster ate a similar amount of FV as the participants in the health control condition. No effect of message type was observed in habitually high consumers of FV with habitual high consumers in all conditions selecting and eating a large amount of FV. These findings indicate that social norm messages emphasising behavioural norms may have more potential than injunctive norms in encouraging healthier eating. They further suggest that social normative information may not bring about behavioural change due to social approval concerns.