The Baader-Meinhof Phenomenon or Frequency Illusion

Have you ever met someone for the first time and then seem to see them everywhere? The Baader-Meinhof phenomenon explains this type of event.
The Baader-Meinhof Phenomenon or Frequency Illusion

Last update: 17 December, 2021

Imagine that one day, during a conversation with a friend, they tell you something about a product or service that you’ve never heard of before. Then, you go home, but suddenly you start to see the product your friend mentioned everywhere. Does that mean that the companies concerned listened to your conversation and then bombarded you with advertising? As a matter of fact, while this may sound intriguing, the answer is somewhat simpler. In fact, you’re experiencing the Baader-Meinhof phenomenon.

This is also known as frequency illusion and is repeatedly experienced by people. However, besides being a curious phenomenon, it has implications in the field of scientific research, medicine, and even marketing.

The Baader-Meinhof phenomenon

We’ve all experienced the Baader-Meinhof effect at some point in our lives. Sometimes, it seems to happen with a product or service. At other times, it might be a certain word or an image. It gives you the impression that, suddenly, what you’ve just discovered, is everywhere.

One common example might be when you meet a new person who lives in the same city or neighborhood. Before the day you met them, you were completely unaware of their existence, but now you see them everywhere. This doesn’t mean that they’re stalking you. In fact, you’re simply experiencing the Baader-Meinhof phenomenon.

You’ll probably be surprised at how suddenly this can happen. Indeed, from one moment to the next, the world seems to have changed and now you see what you’ve just learned about everywhere. For this reason, research has been conducted to better understand this phenomenon.

Friends talking

Why’s it called the Baader-Meinhof phenomenon?

The origin of its name lies in Germany, during the post-war era. In 1986, Terry Mullen sent a letter to a newspaper called the St. Paul Pioneer Press, recounting a personal experience.

According to his account, he’d first read the name of the terrorist group Baader-Meinhof in a newspaper article. However, once he’d learned of its existence, he began to see the name of the organization all over the place.

After his letter was published, Mullen received many letters from other people recounting similar experiences. From that event, Mullen coined the term to describe this strange perceptual phenomenon that provokes such curiosity in people.

Causes of the frequency illusion

When you experience the illusion of frequency, you often have the feeling that you’re being followed. However, this isn’t the case. In fact, it involves different processes that are taking place in your brain. Once you know what they are, you’ll realize that the world hasn’t changed. In fact, everything’s in your mind.

Selective attention

On a normal day, your senses are bombarded by a large amount of information that would be impossible to process completely. For this reason, your brain uses selective attention to discriminate between stimuli. In this way, you’re able to focus only on what interests you. However, how does this relate to the Baader-Meinhof phenomenon?

The new information, which you suddenly see everywhere, didn’t appear out of nowhere. It was always there. What’s happened is that, beforehand, it wasn’t important to you, therefore, your brain ignored it. However, now that you’ve become aware of it, your mind begins to regard it as ‘relevant’ hence you notice it.

Mathematical probability

Although you probably don’t attach great importance to probabilities, they influence your life on a daily basis. Indeed, coincidences happen and they have nothing to do with magic, but with pure mathematics. For example, in a classroom with 25 students, it’s extremely likely that two of them will share the same name or birthday.

This is also relevant in the illusion of frequency. For example, you may well believe that it’ll be virtually impossible to meet your new neighbor on the street. However, if you analyze it with mathematics, you’ll realize that, in reality, the probability is very high.

Brain patterns

In addition to discriminating between relevant and irrelevant information, your brain needs to organize all the information it filters. For this, neural patterns are created that store all kinds of information.

Tong and Pratte (2012) conducted a study in which they explained that it’s possible to decipher numerous psychological processes by analyzing neural patterns. Using neuroimaging, they could tell what a person was seeing or where their attention was directed.

In order for these patterns to exist, it’s necessary that the new information be repeated several times. As a result, the fact of discovering something and then seeing it repeatedly is explained, thanks to this mechanism. In other words, the Baader-Meinhof phenomenon has to do with the brain’s tendency to create patterns.

Implications of the Baader-Meinhof phenomenon in life

Now you understand how this effect works, you might ask what its relevance is to human life? As a matter of fact, it’s something that people experience every day so it has various implications.

Furthermore, if the power of this phenomenon is underestimated, problems can occur. Here are some of them:

Medical diagnostics

Health professionals need to constantly update themselves with new scientific articles. In other words, they’re always acquiring new information that they use in order to offer better treatments. At first glance, there doesn’t seem to be a problem here, but the Baader-Meinhof effect can be rather dangerous in this respect.

For example, an article published in the European Respiratory Journal mentioned the dangers of establishing phenotypes prematurely to diagnose COVID-19. According to the authors, this could create problems in detecting the disease accurately.

In this case, the Baader-Meinhof phenomenon could influence medical judgment due to these new classifications that aren’t well supported (Bos, Sinha, and Dickson, 2020).

Scientific investigation

In the field of research, the illusion of frequency could create bias when analyzing evidence. For example, if an author gets a job that supports a particular hypothesis, perhaps they may later find many other studies that say the same thing. However, inadvertently, they could ignore numerous articles contrary to this argument.

Therefore, those engaged in research must be careful not to fall victim to this bias. It’s also the reason why scientists use double-blind studies and other experimental models. Only in this way, can they ensure that their investigations are as objective as possible.

Brain research


On the other hand, marketing benefits from psychological effects such as the frequency illusion. As stated in the previous examples, this often happens with products or services. As a matter of fact, advertising uses these types of phenomena to reach and generate sales.

In conclusion, we can affirm that the Baader-Meinhof phenomenon has a great influence. Furthermore, it’s one that’s usually underestimated. Like other cognitive biases, it participates in how we perceive the world around us. Although this isn’t entirely negative, it can be at times, so we need to educate ourselves about this illusion.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Bos, L. D., Sinha, P., & Dickson, R. P. (2020). The perils of premature phenotyping in COVID-19: a call for caution.
  • Johnston, W. A., & Dark, V. J. (1986). Selective attention. Annual review of psychology, 37(1), 43-75.
  • Tong, F., & Pratte, M. S. (2012). Decoding patterns of human brain activity. Annual review of psychology, 63, 483-509

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.