Why a claim on its second hearing feels truer than the first

Dechêne, Stahl, Hansen, and Wänke’s meta-analysis of the illusory-truth effect confirmed that a single prior exposure raises truth ratings by a measurable and reliable margin. Participants rated repeated claims as more truthful even when explicitly warned that repetition does not imply accuracy. The warning could not override the fluency signal.

What everyone sees

Listeners believe the claim sounds true because its content is convincing. They do not identify the prior exposure as the source of their confidence. The second hearing is not experienced as a repeat — it is experienced as further confirmation, because the ease of processing feels like agreement from an independent source.

What is actually happening

The illusory-truth effect, replicated across dozens of studies, is driven by processing fluency: prior exposure reduces the cognitive resources required to process a statement, and the resulting ease is misattributed to truth. Unkelbach’s referential-validity model specifies that fluency acts as a validity cue because, in everyday life, true statements are encountered more often than false ones, training the brain to equate familiarity with accuracy.

Why it stays hidden

The effect hides because repetition is everywhere. Advertising, news, and conversation all repeat claims, so the brain has no signal to distinguish genuine evidence from mere re-exposure. Each encounter adds a thin layer of credibility that accumulates below awareness, converting a bare assertion into a felt fact.