Illusory truth effect

What is the illusory truth effect?

The illusion-of-truth effect, also called the illusory truth effect, is a tendency to rate repeated statements as more true than comparable new statements. It can affect judgments of true and false information.

Why repetition can feel like truth

Ye and colleagues’ 2026 meta-analysis combined 182 studies involving 31,184 participants. It found a small average effect after adjustment for small-study effects, with substantial variation across studies.

Familiarity and processing fluency are proposed explanations: a statement encountered before can feel easier to process, and that ease can be mistaken for a sign of truth. Repetition does not make every claim credible or inevitably override what someone knows.

Fazio and colleagues (2015) found that repetition increased truth ratings even for claims that conflicted with knowledge participants could demonstrate. Available knowledge is not always used when a statement feels familiar or easy to process.

Examples in advertising and misinformation

Imagine seeing the same product claim in several ads, or the same rumor repeated across social posts. On the next encounter, the claim may feel familiar before you remember where it came from. The important distinction is between hearing a claim again and receiving independent evidence for it.

Illusion of truth versus illusion of validity

The illusion of truth concerns repeated statements feeling more true. The illusion of validity concerns confidence in a prediction because the available information forms a convincing picture. Both involve a mismatch between confidence and evidence, but repetition and predictive coherence are different issues.

A related concept

Truth bias is a broader tendency to assume that other people’s communications are honest unless there is a reason for doubt. The illusory truth effect is narrower: it concerns repetition increasing a statement’s perceived truth.

Limits and practical implications

Initial exposure conditions, truth cues, and statement type matter. The effect concerns changes in perceived truth; it does not establish the same effect on purchases, votes, or sharing behavior.

Repeated exposure is a reason to check supporting evidence, not a substitute for evidence. Familiarity alone cannot establish whether a statement is accurate.