Proceedings of the Annual Meeting of the Cognitive Science Society

Individuals often encounter the same claims from multiple sources in complex informational environments. Whether such repetition is treated as independent evidence or as redundant testimony depends on assumptions about source dependence. The present study investigates how prior beliefs about the claims shape perceptions of source dependence and how these perceptions influence belief updating. Using a preregistered experimental design, participants evaluated repeated claims presented in vignettes about an online forum. Participants reported both belief change and perceived dependence among sources. We find that lower prior belief in a claim leads to stronger perceptions of source dependence, indicating that prior beliefs shape not only initial judgments but also inferences about the structure of the informational environment. Participants also tended to treat dependence as a global property applying to several sources in the environment. Together, these findings suggest that belief updating reflects rational simplification of informational structure, with important implications for the persistence of belief polarisation.