Think of a claim you have come across several times, in articles, in conversations, in shared posts. You no longer quite remember where it comes from. You have never checked it. Yet it may well strike you as fairly accurate. That feeling of familiarity is not a good indicator of truth, and psychology has given it a precise name.
What we have already seen seems truer
The illusory truth effect is the tendency for repeated statements to be judged truer than new ones. The content has not changed between the first reading and the second. Only the familiarity has. Nothing in the statement itself has become more reliable. The sense of having seen something before is pleasant, and it is easy to mistake it for a sign of accuracy. This is not a weakness confined to a few gullible people: the effect has been shown in laboratory experiments, which invites us to see an ordinary mechanism rather than an individual flaw.
What Fazio and her colleagues show
Lisa Fazio, Nadia Brashier, Keith Payne and Elizabeth Marsh (Journal of Experimental Psychology: General, 2015) asked a precise question. It had been assumed that knowledge stored in memory limited this effect: if you know a statement is false, seeing it again would change nothing. In their first experiment, they tested that idea using normed estimates of knowledge and a knowledge check that participants took at the end of the experiment. The effect appeared even for statements that participants knew to be false. The hypothesis that knowing protects you therefore did not hold, at least under these conditions.
Knowing is not always enough
In the second experiment, statistical modelling showed that participants sometimes relied on processing fluency, that is, on how easily a statement is read and understood, even when they had access to relevant knowledge. The authors describe this as a failure to rely on stored knowledge, which they call knowledge neglect. The word matters: it does not say that people are ignorant, it says that they do not always use what they know. Knowing and using what you know are two different things, and nothing guarantees that the second follows the first.
Why repetition weighs so much
The explanation the authors put forward rests on this fluency: a statement already encountered is processed more easily, and that ease is read as a sign of truth. The second experiment lends it support. That does not make the study a demonstration of the whole mechanism, and other factors may play a part. The practical interest lies elsewhere: the sense of accuracy you feel can come from repetition alone. Reading the same claim three times is not seeing it confirmed three times. It is reading it three times, and the feeling that gets added is one of habit, not of proof.
What the study does not say
It deals with statements evaluated in a laboratory, not with news feeds or disinformation campaigns. Moving from one to the other is an extrapolation, plausible but not demonstrated here. Nor does it say that everyone believes anything: it shows that repetition influences judgment, including in people who had the means to know better. This article offers neither a number of repetitions nor a duration for the effect, since they cannot be established from this one source. Nor does it claim that fluency explains everything, or that we are doomed to undergo the effect with nothing to be done about it. Questions remain open, and acknowledging that is also what honest caution consists of.
What this changes for reading and checking
Knowing that repetition influences judgment does not immunise you, since the study shows precisely that knowing is not enough. What can help is changing the gesture: instead of asking whether a claim seems right, ask where it comes from, and whether you have seen it anywhere other than in the same words. Checking starts there, with a pause. A Cognitive Studio supports that pause by lightening the reading: summarize a long text to see which claims it contains, break it into segments to deal with one passage at a time, listen to it to reread it differently. To be useful at the right moment, a tool like this has to be free, immediate, with no account to create and no length limit. To keep your distance from what you read over and over, seeing a text’s claims at a glance helps you spot the ones you have already come across. A reading tool does not tell you what is true. It leaves time and room to ask the question.
What we have already read feels familiar to us, and the familiar feels right. Remembering that this is only an impression is already a way of reading with a little more distance.