Illusory Truth Effect

What is the illusion of truth effect?

The illusory truth effect is a cognitive bias wherein repetition increases the perceived truthfulness of a statement, regardless of its actual validity. In other words, if an assertion or piece of information is encountered repeatedly, people are more likely to believe it's true, even if they might initially recognize it as false. This phenomenon underscores the power of familiarity - as a statement becomes more familiar, our brains mistake this familiarity for the truth.

This effect has been explored extensively in psychological research. The basic premise is that repeated exposure to a statement increases its familiarity, and this familiarity can be misinterpreted by our cognitive processes as evidence of its truth. This can have significant implications, especially in the age of digital information where false claims can be rapidly and widely disseminated.

What can I do about Illusory Truth Effect ?

Critical Consumption of Information:

  • Fact-Check: Before accepting any piece of information, especially those that are repeated often, make a habit of fact-checking. Reliable fact-checking websites or primary sources can offer clarity.
  • Question Sources: Consider the origin of the information. Is it coming from a reputable outlet? Be wary of sources that have a known bias or those that are not transparent about their origins.
  • Diversify Information Channels: Rely on a mix of news and information outlets rather than just one. Different perspectives can provide a more rounded view of an issue, helping you spot inconsistencies.

Awareness and Reflection:

  • Learn to Recognise the Bias: Being aware of the illusory truth effect is the first step in combating it. By understanding that repetition can make false information seem true, you can be more cautious about readily accepting repeated claims.
  • Reflect Before Sharing: Before sharing something on social media or elsewhere, pause and think. Has the repeated exposure to a claim influenced your perception of its truthfulness?

The repetition effect


Recently, researchers conducted an experiment with two groups where they showed participants trivia statements up to 9 times in group 1 and up to 27 times in group 2. Later, participants rated the truthfulness of the previously seen statements and of new statements. In both groups, the perceived truthfulness increased as the number of repetitions increased.

Interestingly, the truth rating increases were logarithmic in shape. This means that the largest increase in perceived truth came from encountering a statement for the second time, and beyond this were incrementally smaller increases in perceived truth for each additional repetition.


How the illusion of truth relates to disinformation?

Initial Exposure: Even if someone initially recognises a false statement as untrue, the mere exposure to it primes the individual. The first encounter may be via a viral post, forwarded message, or sensational headline. The unfamiliarity might make it stand out, but not necessarily be believed right away.

Repeated Encounters: The illusory truth effect takes hold as individuals encounter the same information repeatedly. This repetition can happen through various channels: shared by friends, discussed on a talk show, or trending on social media. Over time, the sheer frequency of exposure makes the statement seem more true, even if it hasn't been critically evaluated or fact-checked.

Normalisation and Acceptance: As the repeated false statement gets normalised through frequent exposure, people start accepting it as factual. They might feel, "I've heard this so many times; there must be some truth to it." This can lead to false beliefs gaining traction and being spread as truths.

Resistance to Correction: Once the illusory truth effect solidifies a belief, correcting it becomes challenging. Even when presented with factual evidence contradicting the false belief, individuals may still hold onto the misinformation due to the cognitive comfort of familiarity. The often-repeated lie has created an illusion of truth, making it harder to discern real facts from falsehoods.

Disinformation Campaigns Exploit Repetition: Bad actors spreading disinformation are aware of the power of repetition. They use various platforms to echo the same false narratives, knowing that the more often people hear something, the more likely they are to believe it, even if it's false. This is especially potent when combined with other cognitive biases and divisive or emotive topics.

Here are two specific examples where the illusory truth effect was indeed exploited in shaping public perception and triggering political shifts:

Migrant Crisis Narratives
During the height of the European migrant crisis around 2015, there were frequent claims circulated in certain media and political discourse that suggested a majority of the migrants coming into Europe were not genuine refugees but were, in fact, economic migrants or even "terrorists" in disguise. This was despite data from agencies like UNHCR showing a significant number of these individuals were fleeing from conflict zones. Still, the repeated assertions influenced public opinion in many European countries, leading to stricter border controls and migration policies.

EU "Banana Regulation" Myth
One of the most persistent myths in EU history is the claim that the EU wanted to regulate the curvature of bananas, classifying them by their bend. This story has been cited as an example of bureaucratic overreach by the EU, even though it's been debunked several times. The repeated mention of this "fact" led to significant belief in the claim, influencing some people's perceptions of the EU as being overly regulatory, even on trivial matters. Similar myths include imaginary and non-existent "regulations" on condom sizes or fish packaging. Such EU myths were widely used by Leave-side politicians during the Brexit campaign in the UK.

It's essential to understand that the power of the illusory truth effect doesn't just lie in the repetition of a claim, but also in how it's presented, the emotional response it triggers, and the context in which individuals encounter it. In these European examples, repeated claims, whether true or false, have had a noticeable impact on public discourse and policy decisions.

Image by <a href="">Freepik</a>
Image by Freepik

Suggested use in training

Challenge your students to compile a list of statements that can be categorised as false, but so frequently repeated or ubiquitous, that they are almost universally accepted as true. You may give some examples (e.g. we use only 10% of our brains; different areas of the tongue "sense" different tastes; hair grows thicker when shaved; you catch cold if you go out with wet hair)

Allow them time for discussion and internet search. To make things more interesting (and depending on the composition of the group) you may direct their focus to advertising and to myths and misconceptions that have their roots in advertising campaigns ("Breakfast is the most important meal of the day" - Kelogg, "Diamonds are forever" - De Beers).

After students present their findings, start a discussion of why repeated exposure to such statements is so effective in getting them a mythical status and an almost unquestioned association with the truth.