Abstract
Despite growing evidence that warning labels reduce purchases of sugary drinks, less is known about warnings' impact on purchases of sugary snacks. This paper aimed to experimentally test whether a front-of-package label warning about high sugar content ("sugar warning label") would reduce parents' likelihood of selecting a labeled snack versus a non-labeled snack for their child in a food store setting. Participants (n = 2,219 parents of at least one child aged 1-5y) were recruited via an online panel and asked to complete a shopping task in a virtual convenience store. Participants were randomized to one of three labeling conditions: barcode control, text-only sugar warning label, or pictorial sugar warning label. Participants viewed two granola snacks, one labeled and one unlabeled, and selected one for purchase. A post-shopping survey measured secondary outcomes. Predictions and analyses were preregistered on www.clinicaltrials.gov (NCT04381481). Participants exposed to the text or pictorial sugar warning labels were less likely to select the labeled snack than those in the barcode control group (21%, 18%, and 34% respectively; p < 0.001 for both comparisons of warning to control). Relative to the barcode control label, the text and pictorial sugar warning labels resulted in greater attention, anticipated social interactions, negative affect, cognitive elaboration, and perceived message effectiveness, as well as lower perceptions of healthfulness, appeal, and intentions to purchase or consume the product (p < 0.001 for all comparisons of warnings to control). There were no differences in outcomes between text and pictorial sugar warning labels. In conclusion, text and pictorial sugar warning labels reduced parents' likelihood of selecting a labeled granola snack for their children. These results contribute to a growing body of evidence showing that warning labels influence food purchasing behaviors.