Abstract
OBJECTIVE: Many people have a poor understanding of the numerous chemicals in tobacco products that cause severe health harms. The US government must display a list of these harmful chemicals for the public. Online disclosures are one promising solution, but evidence is needed for effective design strategies to encourage interpretation and use of information as intended. METHOD: To examine the impact of website designs for the activation of heuristics and usability perceptions, a national probability sample of US adolescents and adults (n = 1441) was randomized in a 3 (chemical format) × 2 (webpage layout) between-subjects online experiment. Chemicals were displayed as names only, with a visual risk indicator, or with numerical ranges. Layouts displayed health harms at the top of the webpage separate from chemicals or the chemicals grouped by associated health harms. Participants viewed a webpage and reported activated heuristics, usability (perceived ease of use and usefulness), and intentions to use the website. RESULTS: Displaying risk indicators increased website usability by encouraging users to rely on colors to interpret the risk of the chemicals (all p < .01). Website designs that grouped chemicals with harms allowed users to link the chemicals to harms they cause and increased perceived usability and intentions to use the website (all p < .001). CONCLUSION: Assessing heuristics gives insights for how US adolescents and adults interpret chemical information and the impact of design strategies on usability. Public disclosures of chemicals in tobacco products could be optimized with color-coded risk indicators and layouts placing chemicals near the harms they cause.