The illusory truth effect is the tendency to believe false information to be correct after repeated exposure. This cognitive bias occurs because repeated statements become easier to process, making them feel more familiar and, consequently, more truthful to individuals. Familiarity can overpower rationality, leading people to accept repeated statements as true even when they know them to be false initially.
For instance, a commonly quoted false statement is that "Penguins are mammals." Despite someone knowing this to be false, repeated exposure to the statement in various contexts (social media, discussions, etc.) can make them feel uncertain about their initial knowledge and begin to question it due to the familiarity of the claim.
To overcome the illusory truth effect, one should actively question and verify information encountered repeatedly, rather than relying on familiarity. Fostering critical thinking and seeking evidence can help mitigate this bias.