title: Eating less from bigger packs: Preventing the pack size effect with diet primes.
abstract: An increase in the package size of food has been shown to lead to an increase in energy intake from this food, the so-called pack size effect. Previous research has shown that providing diet-concerned individuals with a reminder, or prime, of their dieting goal can help them control their consumption. Here, we investigated if providing such a prime is also effective for reducing the magnitude of the pack size effect. We conducted two experiments in which the cover of a dieting magazine (Experiment 1) and diet-related commercials (Experiment 2) served as diet goal primes. Both experiments had a 2 (pack size: small vs. large) × 2 (prime: diet vs. control) × 2 (dietary restraint: high vs. low) between participants design. We measured expected consumption of four snack foods in Experiment 1 (N = 477), and actual consumption of M&M's in Experiment 2 (N = 224). Results showed that the diet prime reduced the pack size effect for both restrained and unrestrained eaters in Experiment 1 and for restrained eaters only in Experiment 2. Although effect sizes were small, these findings suggest that a diet prime motivates restrained eaters to limit their consumption, and as a result the pack size has less influence on the amount consumed. We discuss limitations of this research as well as potential avenues for further research and theoretical and practical implications.
authors.affiliation: Department of Econometrics, Erasmus School of Economics, Burgemeester Oudlaan 50, 3062 PA Rotterdam, The Netherlands. Electronic address: versluis@ese.eur.nl.
authors.forename: Iris
authors.initials: I
authors.lastname: Versluis
authors.affiliation: Institute of Neuroscience and Psychology, University of Glasgow, 58 Hillhead Street, Glasgow G12 8QB, United Kingdom; Department of Social and Organizational Psychology, Utrecht University, Heidelberglaan 1, 3584 CS Utrecht, The Netherlands. Electronic address: Esther.Papies@glasgow.ac.uk.
authors.forename: Esther K
authors.initials: EK
authors.lastname: Papies
mesh_terms: D000329:Advertising; D002182:Candy / Q000009:adverse effects; D000069956:Chocolate / Q000009:adverse effects; D003657:Decision Making; D000072001:Diet, Healthy / Q000191:economics; D002149:Energy Intake; D005260:Female; D018857:Food Packaging; D006040:Goals; D006801:Humans; D006963:Hyperphagia / Q000191:economics / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D009426:Netherlands; D050177:Overweight / Q000209:etiology / Q000517:prevention & control; D010349:Patient Compliance; D064787:Portion Size / Q000191:economics; D062410:Snacks
keywords: Consumption quantity decisions; Dietary restraint; Dieting goal; Goal priming; Pack size effect; Portion size effect