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Media & Technology

ILLUSORY TRUTH EFFECT

Hasher and Goldstein (1977)

Can misinformation still influence our judgment even after it has been retracted?

Background

On a day-to-day basis, we have to make judgments about the truth or falsity of so many statements that we must generally do so without having the required knowledge. To solve this problem, we resort to heuristics, i.e., rules of thumb that are not entirely rational, but nevertheless practical ways to reach an immediate solution. One such rule is that ideas are more likely to be true the more familiar they sound. This phenomenon, called the Illusory Truth Effect, can be explained by both Zajonc (1968)’s Mere Exposure Effect and Kahneman (2011)’s Dual System Theory. According to the former, repeated exposure to a certain stimulus induces a positive attitudinal change, even if its familiarity remains unconscious. Indeed, as explained by Kahneman in Thinking Fast and Slow, most of our thinking is unconscious and the product of a “system 1” that has evolved as an energy-saving mechanism. As such, system 1 positively values speed and cognitive ease, and thus automatically endorses statements the processing of which is facilitated by implicit memory. More generally, system 1 is guided by the following principle: WYSIATI, what you see is all there is. Another one of its applications is that familiarity can be used as a proxy for more reliable truth criteria, such as peer-review and empirical support. If familiarity leads to “truthiness” (the quality of something that feels true), then mere repetition should be a “major access route that plausible statements have into our pool of general knowledge” (Hasher and Goldstein, 1977), and repeated statements should be more likely to be judged as true than similar non-repeated statements.