Why repetition without new evidence changes minds

A claim is stated three times in a presentation, with no new evidence added after the first stating. Audience agreement rises between the first and the third. The information content has not changed; the feeling of having heard it before has.

What everyone sees

Repetition is treated as emphasis — a way of underlining what the speaker considers important. The audience assumes they are responding to the content, which has not changed, rather than to the repetition, which has.

What is actually happening

Zajonc’s mere exposure effect shows that repeated exposure to a stimulus increases liking for it, independent of recognition. Arkes, Hackett and Boehm found that repeated assertions are rated as more valid, a result consistent with the illusory truth effect. Cacioppo and Petty showed that moderate repetition increases persuasion up to a point, after which tedium reverses it. The mechanism is fluency: a repeated claim is processed more easily, and the ease is attributed to the claim’s validity rather than to the repetition itself.

Why it stays hidden

The mechanism hides because the listener does not detect the source of their increasing agreement. They do not feel themselves thinking “I have heard this before, therefore it is true.” They feel themselves thinking “this makes sense,” and the making-sense is genuine — fluency genuinely produces a sense of comprehension. The error is in attributing the sense to the content rather than to the exposure.