• Social media metrics generate first-person perception (FPP).
• Perceived injunctive norms accounts for the social media metrics effect on FPP.
• FPP induces greater compliant behavioral intentions and social sharing intentions.
• Need to belong moderates the social media metrics effect on FPP.
• Need for closure moderates the social media metrics effect on injunctive norms.
Two experiments investigated how and why social media metrics affect perceived media influence and behavioral intentions. In the first experiment (N = 241), those who viewed a news article about an environmental risk with social media metrics (vs. news article only) reported greater media influence on the self than others (First-person perception, FPP), and such effect was more prominent among those high in the need to belong. Increased FPP, in turn, led to greater intentions to combat the risk. The second experiment (N = 210) found that exposure to a news article about a health risk with