The Effects of Self-affirmation and Normative Information on Processed Food Consumption

Abstract Over the last 50 years, processed foods have contributed to the rise in incidence of common preventable diseases. There is a need for interventions to reduce American intake of processed foods. Social norms can influence a wide variety of behaviors using simple interventions and self-affirmation has been successfully used to reduce defensiveness to negative health risk information. However, little research has explored how social norms and self-affirmation might influence diet behavior and no research has explored the combined influence of self-affirmation and normative information on processed food intake. The present experiment was designed to fill this gap in the literature. Participants were randomly assigned to be self-affirmed or not and also randomly assigned to one of five norms conditions: a descriptive normative message, an injunctive message, or both a descriptive and injunctive message regarding processed food consumption, information on the dangers of processed foods only, or no information (control). Participant intentions were assessed immediately after the interventions and both intentions and behaviors were assessed at four-week follow-up. As had been predicted, it was found that participants who were self-affirmed reported greater intentions to lower their intake of processed foods, however the effects of self-affirmation did not generally extend to changes in behavior (hypothesis 1). Contrary to prediction, information paired with either descriptive, injunctive, or both messages was not more effective than information alone (hypothesis 2), or more effective than either type of normative message alone (hypothesis 3). Also, although the combination of self-affirmation and both message types produced the greatest initial intentions to change compared to all other conditions, this effect did not carry over to the follow-up session or to any measures of processed food intake (hypothesis 4). Considering the health risks posed by processed foods, further research is needed to improve the efficacy of simple dietary interventions such as those used in this study.