Illusory Truth Effect
Repeated statements feel more true regardless of their actual validity.
The illusory truth effect (also known as the illusion of truth effect, validity effect, or the reiteration effect) is the tendency to believe false information to be correct after repeated exposure. This phenomenon was first identified in a 1977 study at Villanova University. The effect is so powerful that even labelling a statement as false before repeating it can make it seem more credible over time.
What it looks like in the wild.
- Politics Political Slogans Campaign slogans repeated thousands of times become accepted as truthful even when factually dubious.
- Marketing Brand Claims Advertisers repeat unverified product claims until consumers accept them as established facts.
Someone has already built a business on this.
Biases are not only private errors. They are design targets — patterns deliberately engineered into interfaces because they reliably work.
- Algorithms and feeds Repetition Loop Algorithm-curated feeds re-surface the same content multiple times across sessions, training users to accept repeated claims as facts.
Recognising a definition is not the same skill as spotting it.
Two scenarios from the app, with distractors drawn from the same family of biases — which is what makes them hard.
After encountering the same dubious investment advice in several financial blogs, a person acts on it, not realizing the advice was promotional content paid for by the very company it recommends investing in directly.
A misleading claim about a city's restaurant hygiene standards repeated in multiple food blogs discourages tourists from dining out, even though the claim was based on inspections during a temporary staffing shortage that has since been resolved.
Biases rarely arrive alone.
Understand more. Assume less.
188 biases, 18,869 scenarios, and a record of how you actually decide.
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