Illusory Truth Effect
The tendency to believe information is true after repeated exposure.
Also known as: Truth Effect, Reiteration Effect, Validity Effect
Category: Cognitive Biases
Tags: cognitive-biases, cognition, psychology, thinking, media-literacy
Explanation
The Illusory Truth Effect is a cognitive bias whereby people are more likely to believe a statement is true simply because they have encountered it before, regardless of its actual validity. This effect occurs because repeated exposure increases processing fluency - familiar information feels easier to process, and this ease is unconsciously interpreted as a signal of truth. The effect is robust and affects even statements that people initially knew to be false.\n\nResearch has shown that the illusory truth effect operates across diverse domains, from trivia facts to political claims to advertising messages. Notably, the effect persists even when people are explicitly warned about it and even when the repeated statements contradict their prior knowledge. This makes it a particularly powerful tool for manipulation through propaganda, misinformation, and advertising, where repetition is strategically used to create belief.\n\nUnderstanding this bias has critical implications for media literacy and critical thinking. In an era of social media where false claims can be repeated millions of times, the illusory truth effect helps explain the persistence of misinformation. Protecting against this bias requires active fact-checking, diversifying information sources, and developing awareness that familiarity does not equal truth. For knowledge workers, it underscores the importance of verifying information even when it feels correct.
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