This randomized controlled online experiment will test whether adding an ultra-processed food (UPF) warning label to the FDA's proposed Nutrition Information Box (NIB) changes consumer perceptions of UPFs among a nationally representative sample of U.S. adults.

Participants will be randomized to one of four label conditions and will evaluate four UPF yogurt products with different nutritional profiles on the NIB. The primary outcome is purchase intent and the secondary outcomes are perceived healthfulness, perceived usefulness and correct identification of UPF products.

This experiment aims to answer the following questions:

Do UPF warning labels reduce purchase intentions compared to the NIB alone? Do UPF warning labels reduce perceived healthfulness compared to the NIB alone? Do UPF warning labels help more consumers correctly identify products as ultra-processed compared to the NIB alone? Do different UPF warning label color designs differ in effectiveness at reducing purchase intentions, lowering perceived healthfulness, and improving correct identification of UPFs?

Researchers will compare outcomes across the four randomized arms to estimate the independent effect of adding UPF warnings beyond nutrient disclosure in the NIB alone.

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.

Inclusion Criteria:

• 18 years of age or older
• Member of the Verasight Panel
• Residing in the United States

Exclusion Criteria:

• <18 years of age
• Not residing in the United States
• Completed the survey in less than one-third of the median completion duration of all participants
• Respondents with high refusal rates (skipped or refused more than 50% of questions)
• Respondents who 'straight-line' all question grids with 6 or more items, where responses are not internally consistent