A Social Norms and Identity Approach to Increasing Fruit and Vegetable Intake of Undergraduate Students in the United Kingdom

Abstract

This study investigated the influence of descriptive norm messages that either communicated that university students eat a sufficient amount of fruit and vegetable (F&V) or that they do not, on F&V consumption, and whether or not any effects are moderated by student identification. An online 2 (Norm: "Sufficient"/"Insufficient") × 2 (Identification: "Low"/"High") experimental design was employed. Infographics containing "sufficient"/"insufficient" F&V intake descriptive norms were presented. An identification manipulation was employed to create "high"/"low" student identifiers. F&V intake intentions were assessed after the manipulations; self-reported F&V intake was reported at 2 days post-intervention. Undergraduate students in the United Kingdom (N = 180) reported their intake intentions, of which 112 (62%) completed the behavioral follow-up. Participants were predominantly white female students from Scottish universities, mean age 20.4 (±1.6) years. Baseline mean F&V consumption was high (4.5 ± 2.8). There were no significant main effects of Norm or Identification manipulations on F&V intentions and intake. Significant norm × identification interactions were revealed for fruit intake intentions and vegetable intake at follow-up, indicating half-portion differences (~40 g) between groups. Ironic effects were observed for "high" identifiers, who neither intended to, nor acted in accordance with group norms; "low" student identifiers intended to and followed group norms, whereby the "sufficient"/"low" group intended to consume significantly more fruit portions and consumed more vegetables than the "insufficient"/"low" group. Given the half-portion differences between groups resulting from the norm × identification interactions, future research on a larger sample of young adults with low F&V intake is warranted to further explore the conditions under which moderating effects of identification are observed and the underlying mechanisms.

Keywords: descriptive norm; eating behavior; fruit; identification; social norms; vegetable.