Believing after just two times | The scariness of the "illusory truth effect" that even I, a psychologist, was surprised by: A paper introduction

Have you ever found yourself believing something even though you were thinking, "Is that information really true?"

Stories that appear on your social media timeline over and over, reports you see repeatedly in the news, claims you hear again and again from family and friends. Have you ever been startled to realize that, despite being skeptical at first, you have somehow come to accept them as "probably true"?

As a certified public psychologist, I face the mysteries of human cognition in the medical field every day. Recently, I read an interesting paper and felt compelled to share it with as many people as possible. It is a study that carefully examines how information we are repeatedly exposed to shapes our "feeling that something is true."

Today, I will talk about its contents while incorporating my own experiences from the clinical field.

Why do we believe "stories we've heard many times"?

Please imagine this for a moment.

One morning, a post appears on social media saying, "A certain food is bad for your health." At first, you think, "Is that true?" and scroll past it lightly. At lunch, someone else is talking about the same thing. In the evening, a similar topic comes up on TV. The following week, when that topic comes up in a conversation with your family, you might suddenly find yourself saying, "Oh, I've heard that too. Apparently, it's not good for you."

A story that was "half-believed" at first has somehow turned into a "fact" within you. This is a phenomenon in psychology called the "illusory truth effect."

A paper published by Hassan and Barber in 2021 examines this effect on a large scale. To briefly explain the study, participants were shown trivia-like sentences a varying number of times—1, 3, 5, 7, or 9 times (up to 27 times in Experiment 2)—and were asked one week later, "Do you think this is true?"

The results were clear. The more often participants saw a sentence, the higher the percentage of them who "felt it was true." This occurred regardless of whether the original content was true or false.

The three discoveries that surprised me the most

While reading the paper, there were three points that I felt particularly "align with my experience in the field."

The first is that the "second time" has an overwhelmingly large impact.

Looking at the graph, the increase in the "degree of belief" is sharpest when moving from the first time you hear it to the second time. To use an analogy, once the first footprint is made on a pristine snowfield, subsequent footprints are easier to make there. Something similar happens in the brain; a path of thought that has been traveled once becomes much easier to travel the second time. Researchers explain this using the term "processing fluency." We feel that information the brain can process smoothly is "truth-like."

The second is that the "effect does not increase infinitely even with repetition."

In the experiment, the increase in the degree of belief leveled off after about 9 repetitions. Even after 27 repetitions, there was no significant difference compared to 9 times.

This is called a "logarithmic function change," and if you think of it as a slope, it's like passing the initial steep uphill climb and then continuing on a gentle flat road. It also overlaps with the phenomenon known in the advertising industry as "wear-in, wear-out." That feeling where showing the same advertisement too much reduces its effectiveness.

And the third, which is the scariest part, is that "even if we have prior knowledge, we get deceived."

Past research has shown that even "obviously strange claims" or "claims that contradict one's own knowledge" increase in "truth rating" when exposed repeatedly. Even impossible sentences like "The Earth is a perfect square" make us feel a little bit like "maybe it's true" when repeated. The paper introduced this specific example: "Trump repeated 'the construction of the wall has already begun' 86 times during the 2016 presidential election. Even though it wasn't a fact, every time it was repeated, the claim gained more 'truth-likeness' among people."

When I read this, I couldn't help but groan.

What is happening inside your own head is actually the same

From here on, I would like to talk about "another kind of scariness" that I feel as a certified public psychologist.

This illusory truth effect is not just about information from the outside. The words you repeat to yourself may also be subject to the same phenomenon.

For example, "I am a useless person," "I won't be able to keep this up anyway," "This isn't for me." If you mutter such words in your head every day, those words, which you might have been skeptical about at first, will eventually start to feel like "unshakable facts."

This is a scene I often encounter in medical settings as well. While the person intends to be "just stating facts," in reality, that "self-evaluation they believe to be a fact" might itself be an illusion created by years of repetition. When you think about it that way, doesn't your perspective change a little?

Conversely, there is also hope. If negative self-evaluation is created by repetition, it means it can be rewritten through repetition. Affirmations (positive self-declarations) likely have a certain effect because they skillfully utilize this property where "the brain tends to perceive repetition as truth."

What we can do as we swim in the sea of information

For those of you who thought, "So, what should I do?", I would like to recommend asking yourself the following small questions from time to time.

"How many times have I encountered this information now?"

"I might be believing this not because it is correct, but because I see and hear it often."

"Where did the words I am repeating to myself in my head right now come from?"

Noticing that you "believe" something is quite a difficult task. That is precisely why taking even a little time to stop and check your own cognitive habits is something I feel will become an increasingly important habit for us living in an era overflowing with AI and information.

While reading the paper, I was reminded of a line from the movie "The Matrix": "Do you believe what you are seeing, or are you seeing what you believe?" In a world overflowing with information, I think once again that noticing what you are accepting as "truth" is the first step toward taking your life back into your own hands.

Conclusion

I will summarize the content of this article into three points one last time.

First, information you are repeatedly exposed to becomes easier to feel as "truth," regardless of whether it is correct or not. This is the illusory truth effect.

Second, the most effective one is the "second time." When moving from the first time to the second time, our "feeling of belief" shifts the most significantly.

Third, that effect plateaus at around nine times. However, in this day and age, there are plenty of opportunities to encounter the same information nine times.

And this is not just about outside information. The words you repeat to yourself also become "truth" through the same mechanism. That is why I want you to listen closely to the narration flowing inside you from time to time.

What you repeatedly hear and what you repeatedly tell yourself. You, and no one else, hold the choice. I think this is a truly powerful fact.

If you found this article helpful, it would encourage me if you could let me know by clicking 'like' or following. I will continue to post on the same theme, so I look forward to your continued support.

Reference: Hassan A, Barber SJ. The effects of repetition frequency on the illusory truth effect. Cogn Res Princ Implic. 2021;6(1):38.

#Illusory truth effect #CognitiveBias #InformationLiteracy #Psychology #SelfCare