illusory truth effect - the misconception that arises when repeated exposure to a message increases the likelihood that it will be perceived as true.

This bias arises because repetition enhances familiarity, and familiarity is often mistaken for accuracy. When people repeatedly encounter the same information, even if they know it is false, they are more likely to believe it over time. For example, a claim like "vaccines cause autism" becomes more believable to some people after hearing it repeated multiple times, even if they know there is no scientific basis for it.

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Why It Works

The illusory truth effect works because the human brain relies on familiarity as a mental shortcut to assess credibility. When information is repeated, it becomes easier to process, and this cognitive fluency creates the illusion of truth. This effect is amplified in environments with high information saturation, where the sheer volume of repeated claims can overwhelm critical evaluation.

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How It's Used

The illusory truth effect is often exploited in propaganda, advertising, and political rhetoric. Politicians or interest groups may repeat simple slogans or misinformation to embed them in public consciousness, knowing that repetition increases acceptance. Social media platforms also inadvertently contribute to this effect by repeatedly circulating the same content, making it feel more familiar and, therefore, more trustworthy to audiences. A baseless conspiracy theory, if shared widely enough, can gain traction simply because of its repeated exposure.

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