Why a fact sounds truer the second time you hear it

A claim appears in a quiz. Participants who encountered the same claim an hour earlier rate it as more likely to be true than participants seeing it for the first time. The claim was not verified in the interval. Nothing new supports it. It has simply been encountered before.

What everyone sees

The participant attributes the feeling of recognition to having seen the claim confirmed somewhere, or to it being common knowledge. The possibility that mere repetition, without any new evidence, is the reason it feels true is not the explanation people reach for.

What is actually happening

Hasher, Goldstein and Toppino demonstrated the illusory truth effect: repeated statements are judged truer than novel ones, regardless of their actual truth value. Dechêne and colleagues meta-analysed the effect and confirmed its robustness across content types and delays. Fazio and colleagues showed the effect persists even when the repeated statement contradicts the participant’s prior knowledge, though prior knowledge attenuates it. The mechanism is processing fluency: a repeated stimulus is processed more easily, and the ease is read as a signal of truth.

Why it stays hidden

The signal hides because fluency feels like understanding. The reader does not experience “this is easy to process”; they experience “this is clearly true,” and the clarity is genuine — it is just not evidence. Separating the two would require noticing that the feeling arrived before the judgement, and that sequence is too fast to observe.