The Effect of Popularity Cues and Peer Endorsements on Assertive Social Media Ads

Social media platforms, like Facebook, often display assertive call-to-action (CTA) ads that encourage direct purchases or app installs. These ads can show popularity cues (e.g., number of “likes”) and peer endorsements (e.g., friends who “liked” the ad). Although such signals can positively influence user engagement for informational ads, our research reveals they can backfire for assertive CTA ads. Through field tests on Facebook and incentive-compatible experiments, we find that popularity cues do not improve and that peer endorsements actually harm click performance on assertive CTA ads. The negative effect of peer endorsements is amplified when they come from dissimilar friends. Underlying this effect is users’ persuasion knowledge getting activated; they view these signals as manipulative advertising tactics for the assertive CTAs, resulting in psychological reactance. However, the detrimental impact is mitigated when peer endorsements come from friends with similar preferences. For advertisers, our findings suggest discounting popularity and peer endorsement metrics when evaluating assertive CTA ad performance. Platforms, like Facebook, should also consider making these signals optional for such ads. Overall, exercising discretion with these social proof signals for assertive purchase/install messaging can improve advertising outcomes.