An Experimental Test of the Persuasive Effect of Source Similarity in Narrative and Nonnarrative Health Blogs

Background: Blogs, or websites containing online personal journals, are a form of popular personal communication with immense potential for health promotion. Objective: Narratives are stories with a beginning, middle, and end that provide information about the characters and plot. Source similarity refers to the degree to which the message source and each recipient are alike with respect to certain attributes. Narratives and source similarity have seldom been examined in tandem as strategies for health persuasion. Personal health blogs provide a suitable platform for such an investigation. This study examined the persuasive effects of message type and source similarity on participants' intentions to adopt a specific health behavior (running for exercise). Methods: A total of 150 participants were randomly assigned to conditions (n=25 per condition) in a completely crossed, 2 (message type: narrative and nonnarrative) × 3 (source similarity: no similarity, non-health-related similarity, and health-related similarity) between-subjects experiment. First, in an online questionnaire, participants provided personal information in 42 categories and rated the relatedness of each category to running and then completed pretest measures of the dependent variables. Based on their responses, 150 personal health blogs were created. Two weeks later, the initial participants read the blog created with their personal characteristics and completed a questionnaire online. Results: The source similarity effect was stronger in nonnarrative than narrative blogs. When the blogs were nonnarrative, those with health-related similarities were more persuasive than those with non-health-related similarities. Narrative blogs generated more positive thoughts and stronger blogger identification than nonnarrative blogs. Conclusions: Health-related source similarity is key for persuasive health communication, especially when the messages are nonnarrative.