Causal Language in Health Warning Labels and US Adults' Perception: A Randomized Experiment.

Objectives. To examine US adults' reactions to health warnings with strong versus weak causal language.Methods. In 2018, we randomly assigned 1360 US adults to answer an online survey about health warnings for cigarettes, sugar-sweetened beverages, or alcohol. Participants rated 4 warning statements using different causal language variants ("causes," "contributes to," "can contribute to," and "may contribute to") displayed in random arrangement.Results. Most participants (76.3%) selected the warning that used "causes" as the 1 that most discouraged them from wanting to use the product. "Causes" was also selected most often (39.0% of participants) as the warning that participants most supported implementing. By contrast, most (66.1%) chose "may contribute to" as the warning that least discouraged them from wanting to use the product. We found few demographic differences in these patterns.Conclusions. Warnings with stronger causal language are perceived to be effective and are supported by the public.

Impact of e-cigarette health warnings on motivation to vape and smoke.

BACKGROUND: A prevailing hypothesis is that health warnings for electronic cigarettes (e-cigarettes) could drive people away from vaping and towards smoking cigarettes. We consider an alternative hypothesis that e-cigarette warnings discourage both vaping and smoking. METHODS: Participants were a national convenience sample of 2218 US adults who used e-cigarettes, cigarettes or both. In August 2018, we randomised participants to one of three warning types (control text about littering, text-only e-cigarette warning or pictorial e-cigarette warning). We further randomised participants viewing e-cigarette warnings to one of three topics (nicotine addiction, health hazards of use, or both health hazards and harms of use). The preregistered primary outcome was intentions to quit vaping among e-cigarette users. Secondary outcomes included interest in smoking and Tobacco Warnings Model constructs: attention, negative affect, anticipated social interactions and cognitive elaboration. RESULTS: Text warnings elicited higher intentions to quit vaping than control among e-cigarette users (d=0.44, p<0.001), and pictorial warnings elicited still higher intentions to quit vaping than text (d=0.12, p<0.05). Text warnings elicited lower interest in smoking compared with control among smokers (p<0.05); warnings had no other effects on interest in smoking among smokers or non-smokers. Text warnings about health hazards elicited higher intentions to quit vaping than nicotine addiction warnings. E-cigarette warnings also increased Tobacco Warnings Model constructs. DISCUSSION: E-cigarette health warnings may motivate users to quit vaping and discourage smoking. The most promising warnings include health hazards (other than nicotine addiction) and imagery. We found no support for the hypothesis that e-cigarette warnings could encourage smoking cigarettes.