Conspiracy or Public Service? Does Facebook’s Third-Party Fact-Checking Increase Conspiracy Beliefs Among Americans?

Unlike past studies that examine whether fact-checking can counter conspiratorial belief, we reverse the lens to investigate if fact-checking itself prompts conspiracy belief. Our study occurs in the days immediately preceding the 2024 US election. Shortly thereafter, Meta’s CEO Mark Zuckerberg abandoned Facebook’s third-party program altogether, arguing fact-checkers “have destroyed more trust than they have created.” We provide timely insight into fact-checking concerns using a preregistered online survey-based experiment of US Facebook users’ ( n = 2,409), randomly assigned to view either a generic Facebook fact-check (treatment) or a Facebook login screen. Results show no overall effects of third-party fact-checking on users’ propensity for conspiratorial beliefs. However, when individuals with high conspiracy mentality and strong conservative identification encounter a fact-check, they are more likely to endorse Facebook-related conspiracy beliefs. We also observe a three-way interaction among political independents with high and low conspiracy beliefs, where fact-checking potentially triggers or reduces such beliefs.