Proceedings of the Annual Meeting of the Cognitive Science Society

When assessing the quality of health information encountered online, reasoners may rely on the wisdom of others and the degree of consensus apparent. However, it is unclear whether reasoners weigh the opinions of others evenly or make assumptions about the amount of evidence that each has seen. We investigated this question in an online experiment where people were asked to rate their belief in a series of health claims both before and after reading responses from other users. The degree of consensus among these users and their level of expertise (non-experts vs. expert organisations) was manipulated within-subjects. While we found belief change increased monotonically with the degree of consensus for both experts and non-experts, our results indicate qualitatively different patterns of increase between the two groups. Our study suggests that people reason from consensus using nuanced assumptions about the evidence underlying other people's opinions.