Hearing a false claim twice makes it feel more true

Villanova and Temple researchers read college students trivia statements across three sessions two weeks apart. Statements repeated in later sessions were rated as more likely true than new ones — even though repetition says nothing about accuracy. The effect holds even when people already know the correct answer, which is why familiar falsehoods can out-compete facts.

— Lynn Hasher, David Goldstein, Thomas Toppino, Frequency and the Conference of Referential Validity — Journal of Verbal Learning and Verbal Behavior, 1977