Inferring Norms from Numbers: Boomerang Effects of Online Virality Metrics on Normative Perceptions and Behavioral Intention

Abstract Online virality metrics have been shown to influence information processing and behavioral outcomes. This study examined how virality metrics, in terms of the number of online shares, impacted the persuasiveness of a health campaign message in influencing viewers’ evaluation of the message, their perceived injunctive norms, descriptive norms, and preventative behavioral intentions. We conducted a 4 by 2 factorial online experiment (N = 621), featuring an HIV prevention video accompanied by a virality metric (i.e., high, medium, low, and no metric) and a video poster (i.e., demographic similarity versus dissimilarity). Results showed that virality metrics did not influence message evaluation. However, the presence of metrics decreased viewers’ perceived injunctive norms supporting condom use and HIV testing, which further decreased the corresponding behavioral intentions. The similarity between the viewer and the poster did not moderate the effects of virality metrics. These findings suggest a boomerang effect of virality metrics in reducing the persuasive impact of health messages. Theoretical explanations and practical implications are discussed.