Judging the Believability of Social Media Misinformation: Source, Message Distinctiveness and Individual Values

Does the source and distinctiveness of misinformation in social media posts affect its believability? Across two studies, we examine this question utilizing vignette experimental survey designs that manipulated the source, accuracy of information, and whether the information was common or distinctive (uncommon). Four different topics with different political or moral positions were used to assess how effects varied across topics. True posts were found to be more believable than misinformation posts across the four topics in Study one (n = 595), supporting recent reviews (Gawronski, Nahon & Ng, 2025). In study two (n = 514), misinformation was rated as more believable, more accurate, and more trustworthy if it was uncommon rather than common. For both studies, source effects were significant but smaller than the distinctiveness effect. Posts from the source of authority were rated as more believable than those from a friend. Distinctive messages receive initial assessments of higher credibility, suggesting heuristic process. However, the personally relevant topic of Covid, showed higher believability for uncommon misinformation, but also a higher percentage intending to verify the information through additional research and to share the post. Individual differences in political orientation and moral purity values had significant, but very small effects compared to the effect of distinctive messages. These findings are consistent with the Elaboration Likelihood Model of Persuasion (Petty and Cacioppo, 1986). Implications and directions for future research are discussed.