  The present study investigates the role of source characteristics, evidence
quality, crowdsourcing platform, and prior beliefs of the topic in adult
readers' credibility evaluations of short healthrelated social media posts.
Researchers designed content for the posts concerning five health topics by
manipulating source characteristics (source's expertise, gender, and
ethnicity), accuracy of the claims, and evidence quality (research evidence,
testimony, consensus, and personal experience) in the posts. Then, accurate and
inaccurate posts varying in these other manipulated aspects were
computer-generated. Crowdworkers (N = 844) recruited from two platforms were
asked to evaluate the credibility of ten social media posts, resulting in 8380
evaluations. Before credibility evaluation, participants' prior beliefs on the
topics of the posts were assessed. Results showed that prior belief consistency
and source expertise most affected the perceived credibility of accurate and
inaccurate social media posts after controlling for the topic of the post. In
contrast, the quality of evidence supporting the health claim mattered
relatively little. In addition, the data collection platform had a notable
impact, such that posts containing inaccurate claims were much more likely to
be rated higher on one platform compared to the other. Implications for
credibility evaluation theory and research are discussed.
