Testing the effects of certain versus hypothetical language in health risk messages

This paper tests how certainty conveyed through language can be harnessed to enhance the effectiveness of health risk messages. We conducted experiments with low-income, adult smokers (n = 317) and middle schoolers (n = 321) on pictorial cigarette warning labels. We manipulated hypotheticality of risk through verb modality: present tense, may, can, and will. For adult smokers, present tense led to greater health risk beliefs, compared to hypothetical, among adult males but not females. For youth, contrary to what might seem intuitive, the hypothetical may verb was more effective than the present tense language in promoting health risk beliefs, which was associated with reduced susceptibility to use cigarettes. We discuss the findings in relation applications of construal level theory to health communication.