Repetition → understanding → beliefOne of the factors which underlies the belief in untruth is the ease with which we can understand statements. The easier a statement can be understood, the more we are inclined to believe it is true. One of the things which contributes to how easy we can process and understand statements is that they are repeated often. The more often a statement is repeated, the easier it becomes to process and the more likely we are to believe it is true.
Fazio et al. (2015) wondered whether the availability of knowledge protects against the phenomenon that repeated untruths are believed. To their surprise they found, in two experiments, that people, even when they have correct knowledge which contradicts the false statement, tended to start believing it when it got repeated. The fact that a statement is easy to process apparently outweighs the knowledge we have about the topic.