What works best: Objective statistics or a personal testimonial? An assessment of the persuasive effects of different types of message evidence on risk perception.

OBJECTIVE: In an experimental online study we compared the effects of different types of persuasive evidence in promoting the acceptance of a personal health risk. DESIGN: 118 men who have sex with men (MSM) at-risk for infection with the hepatitis B virus (HBV) were recruited via a range of websites and randomly assigned to one of 4 conditions (2 experimental and 2 control): narrative evidence (i.e., a personal account), statistical evidence (i.e., abstract prevalence data), mere assertion of increased risk, and no risk information. MAIN OUTCOME MEASURES: Narrative evidence was expected to be more effective than statistical evidence in increasing MSM's perceived risk of infection with HBV and intention to obtain vaccination. RESULTS AND CONCLUSION: As predicted, perceptions of personal risk and intention to obtain vaccination against HBV were highest after presentation of narrative evidence, and risk perception mediated the effect of type of message evidence on intention. We propose that narrative evidence effectively promotes a sense of personal risk because it is less affected by defensive message processing resulting from the threat to important self-beliefs that seems inherent in health risk communication.