Information Sampling, Belief Synchronization, and Collective Illusions

We demonstrate that a sampling‐based mechanism can offer an alternative explanation for belief synchronization in social groups and the persistence of collective illusions. Our model assumes that people are more likely to sample popular alternatives than unpopular alternatives. We show that this mechanism is sufficient to explain belief synchronization: a strong majority of opinions will likely emerge in favor of one alternative. The reason is that the group is unlikely to move away from a state in which one alternative is very unpopular. If by chance most people come to dislike alternative A, they are all unlikely to sample it again and their opinions of A remain the same. When A is in fact the best alternative, a collective illusion has emerged because people mistakenly believe that a suboptimal alternative is the best. Our model implies that such a collective illusion is persistent. The model thus offers an existence proof that a collective illusion can occur even in settings where people do not infer that popular alternatives are better. The model also casts new light on the effect of online recommendation systems on attitude homogenization and the effect of majority voting on beliefs and attitudes. This paper was accepted by Yuval Rottenstreich, judgment and decision making.