There’s a cartoon that shows a the philosopher, Plato, sitting on the grass of Athens with a modern-day politician (variously, it is Karl Rove or Donald Trump), with the latter character saying to Plato, “But surely you agree that truth can be created by the repetition of a lie.” We might think that smart listeners would be wise to that, but the research seems to suggest otherwise. A recent research release from the British Psychological Society reports on a study showing what is called the “Illusory Truth Effect” (Brashier, Eliseev & Marsh, 2020), or the tendency to treat a claim as true based on repetition. The effect occurs as we become more fluent in processing thoughts that we have heard repeatedly, and we then mistake that fluency for reliability or truth. In other words, the familiarity makes it “feel” more true.

Of course, the courtroom is designed to be a setting where evidence, and not repetition, is what creates truth. Despite that, however, the effectiveness of repetition can still creep in. Repeated claims might be made in voir dire, openings, or closings, or in the language of questions asked during testimony. The attorney repeatedly asking about “the missed diagnosis” in a medical case, for example, might be successful in planting that understanding of events, even as the witness tries to correct it. In this post, I’ll take a look at the study and its implications for repetitive-language strategies in the courtroom.

The Study: Repeating Makes It True

The researchers asked participants to view a series of statements, some of them true and some of them false, and to rate them initially based on interest, but later based on whether they were likely to be true or false. What they found was that even false statements gain a certain truth value if they are repeated. The research participants “rated false statements which they had already seen as more true than false statements which were new.”

Don’t Take Repetition Lightly

You might tend to assume that people of average to higher intelligence, or those who take an oath to be impartial, would be wise to the tactic of simple repetition. But, interestingly, the researchers found that this effect was unrelated to both intelligence and cognitive style: People who are able to see past the repetition effect will still tend to be influenced. The repetition creates a familiarity which can start to feel true. So when a Plaintiff’s attorney is persistently referring to “safety” as the standard in a case, that can create a durable context. To prevent concepts like that from taking root in discovery and trial, it is necessary to counter that repetition every time you hear it.

Nudge Jurors Toward Critical Thinking

Having found that people are prone to the repetition effect, regardless of their own intelligence or individual cognitive style, the researchers argue that listeners need to be motivated to be more critical. “Using our own knowledge to fact-check a false claim can prevent us from believing it is true when it is later repeated,” they note, “But we might need a bit of a nudge to get there.” That nudge can be accomplished, they found, by emphasizing critical analysis: “Using our own knowledge to critically analyze a statement when we originally encounter it may inoculate us against the illusory truth effect.” In the study, when participants are asked to judge the statements upon first hearing them, the illusory truth effect seems to disappear. So for jurors, the advice is to emphasize their particular role and ‘temporary identity‘ in the courtroom as the ultimate checks on accuracy:

Your job is to decide what is accurate and what isn’t. That is your role here in the courtroom, and you are the only ones who have that unique mission. Your job is to decide what has been proven and not to just react to what sounds good, or to what’s been said repeatedly. It is about proof, not persistence.