Testing Ultra-processed Warning Labels in United States

Four-arm parallel randomized controlled trial (RCT) in a nationally representative online survey. Participants (n≈7,000) will view identical product images with different UPFWL: NIB only Control, NIB + UPF label Yellow, NIB + UPF label Red, NIB + UPF label Black. Between-subjects design. Each participant will see one label condition across four products (presented in a random order). Outcomes will be measured via Likert scales and binary classification. Randomization implemented in Qualtrics with simple equal allocation. After viewing each product participants will answer questions about the intention to purchase the product, how healthy the participant thinks the product is, and whether or not the product is a UPF. After presentation of the 4 products, the label will be displayed again and participants will answer questions about how useful the participant thinks the label is for making decisions about how well a food fits into a healthy diet. The investigators hypothesize that all UPF warning labels (UPFWL) will be more effective than the Nutrition Information Box (NIB) alone, with the red UPF warning label being the most effective, followed by the yellow label, and the black label being the least effective at reducing purchase intention, lowering perceived healthfulness, increasing perceived usefulness, and improving correct identification of ultra-processed products.