What Is… the Frequency Illusion (Baader-Meinhof Phenomenon)

Insights into psychology: The frequency illusion, aka Baader-Meinhof phenomenon

In this series, I dig a little deeper into the meaning of psychology-related terms. This week’s term is the frequency illusion, also known as the Baader-Meinhof phenomenon.

Do you ever find that once you start to notice something, all of a sudden, it’s happening a lot? There’s a name for that; it’s a type of cognitive bias called the frequency illusion, which was described by linguist Arnold Zwicky in 2005. He first wrote about it in the context of linguists’ perceptions about how common certain patterns of speech were.

The frequency illusion refers to the same concept that was previously described as the Baader-Meinhof phenomenon. This name came about after “Gigetto on Lincoln” wrote on the Pioneer Press Bulletin Board about this phenomenon he had named. He came up with it after speaking to a friend about the Baader-Meinhof gang (a West German extremist group), and the friend pointed out an article in that day’s newspaper that mentioned the group. Other readers shared that they’d had the same sorts of experiences.

The frequency illusion is the product of selective attention and confirmation bias, often with a dash of recency illusion. Let’s look at what those things are.

Selective attention

You’re probably awake for about 16 hours a day. Think of the amount of input that you’re constantly bombarded with during that time. Selective attention is the way that our brain selects what’s relevant and ignores irrelevant stimuli. There’s only so much attention to go around, and it’s just not possible for everything to register. Imagine how overwhelming it would be if our brains couldn’t filter out information.

Treisman’s attenuation model, shown below, shows how we filter sensory input. These filters are based on what we’re intentionally paying attention to, physical properties like loudness, and then analysis of meaning. Our names, for example, are very meaningful to us, so we’re likely to selectively attend to input that includes our name. Things only make it into working memory if they’ve passed through those filters.

Treisman's attenuation model of how sensory inputs are filtered

That means that things that don’t make it through the selective attention filters aren’t encoded in memory. You don’t remember things as they actually happened; you only remember the bits that caught your attention. That means that there’s a shit ton of stuff that happens each day that you can’t possibly remember because it was never stored in your memory in the first place.

Confirmation bias

Confirmation bias means that we tend to seek out and believe things that are consistent with what we already believe and ignore evidence that’s inconsistent with our beliefs.

Once something has grabbed your attention, you’re likely to notice almost every instance of it that you come across. This skews your perception of the frequency, leading you to think that the frequency has changed. Each time you come across that thing, that confirms your perception that the frequency has increased, and you’re even more sure that you’re now seeing it all the time.

Meanwhile, you could’ve seen the same thing 20 times last week and not remember because it didn’t make it through your attention filters any of those times. The fact that you don’t remember can be interpreted as confirmation that it wasn’t happening, but it’s not possible to fish things out of your memory that weren’t encoded there in the first place.

The recency illusion

The recency illusion makes us think that things that we’ve just noticed or learned about are recent phenomena. Zwicky gives the example of an article on a dictionary website about people misusing “you and I” where they should have used “you and me”. The author of this article thought that this misuse was a hypercorrection that had arisen in the last 20 years or so because of schools emphasizing the “you and I” construction. I certainly remember being corrected for saying “me and Jane played soccer at recess.” However, Zwicky (2005) pointed out that sources show this has been going on for a good 400 years, and “it’s not just Kids These Days.”

The recency illusion often accompanies the frequency illusion. It supports the idea that the thing we think we’re coming across all the time now wasn’t happening at all before. It’s new in our attention, so we think it’s new in general.

Besides having a lot of sensory input each day, we also have a lot of thoughts. Many of them are pretty fleeting, and they may come and go without us remembering them. A study conducted at Queen’s University found that we have about 6200 thought worms a day. These are trains of thought with transitions between them; the thoughts themselves can’t be detected, but the researchers believed they were able to see transitions. We’re not remembering all of those thoughts, which skews our ability to remember how we think about things.

Another possible explanation for a perceived increase in frequency is our inability to wrap our heads around the notion of randomness. We naturally seek patterns, and we’ll find them even when they don’t exist (this is called apophenia).

Examples of the frequency illusion

During pre-COVID times, think about how many people you would see during an average day. You go out and about in your neighbourhood, you go to the grocery store, you commute to work, etc., and there’s a big sea of people you mostly don’t pay any attention to. Let’s say that one day at the grocery store, you trip, and someone catches you and prevents you from falling. Over the next few weeks, all of a sudden you’re seeing this person everywhere, and you don’t remember ever seeing them before. But if they were part of the great big sea, there would have been no reason for you to notice them before. After they helped you, though, you’re likely to notice them every time you come across them, and each time you see them, it reinforces the idea that you’re seeing them everywhere.

If you’re in the market to buy a new car, and you’re considering a particular kind of car, all of a sudden that make of car will jump out at your from the great big sea of cars that you usually pay no attention to.

One article that I came across mentioned that the frequency illusion may be treated as evidence that delusions are true for people experiencing psychosis. If you think that light switches are a way of people spying on you, you’ll suddenly start to notice the loads of light switches that you completely ignore most of the time.

Perception isn’t all that reliable

Zwicky (2005) points out that while sometimes your perception of a change in frequency can be correct, it’s important to confirm that with facts rather than just assuming that your perception is reliable when it’s really “seat-of-the-pants guesses.”

The frequency illusion is very common. Zwicky noted that linguists are particularly like to be affected by the frequency illusion regarding written or spoken language. It’s not a matter of not knowing better; our perception just isn’t as reliable as we might like to think it is.

Is this cognitive bias something that you’ve noticed in your own experience?


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Ashley L. Peterson headshot

Ashley L. Peterson


Ashley is a former mental health nurse and pharmacist and the author of four books.

37 thoughts on “What Is… the Frequency Illusion (Baader-Meinhof Phenomenon)”

  1. I’ve noticed that BMW drivers are the worst, but it is true that Ford pickup drivers often suck too… I guess I haven’t noticed all the Toyotas cutting me off 😂

  2. Thanks for the post — did not know there was a name for this….

    In 1989, my Dad died from cancer. After that my perception was that cancer was everywhere I looked. I am pretty sure this is my version of a frequency illusion.

    In the past 30 to 35 years the frequency illusion perception has returned more to normal – thankfully. But, I am still aware of cancer cases probably more than most people.

  3. I can’t give any examples but I’m sure this applies to me – I am a pattern seeker which is what always made me good at my jobs and I think contributes to my ultra-organizational skills – and my preference for poetry. I’m one of those people who doesn’t believe in coincidence so not only do I pattern seek but probably experience frequency illusion and then try to attach meaning to all of it. But I’m good with all that…

      1. I don’t process visual patterns very well- my depth perception and figure/ground perception are seriously lacking, impacting my spatial abilities negatively. I was always thought I was clumsy, turns out I just don’t see very well…

  4. I see a lot of confirmation bias and stereotyping with the people I work with. One coworker was so bad for it that he labelled every act of bad driving once as being something women or a specific race do. I’m sure he sees white men do all of those things he labelled, but it never registers in his mind because white men (like himself) don’t stand out to him. Contrarily, I see white men do stupid things on the road daily.

  5. Teagan and Her Horses

    I’ve experienced this on a number of occasions and always kind of wondered about it. Interesting read, thank you.

  6. I am totally fascinated with the Baader-Meinhof phenomenon. I have the opposite of recency. When a great singer comes along, I assume everyone else knows this artist and I’m the last one to hear them.😆😆😆😆

  7. Oh, we’re all about the confirmation bias, as a species. It can be a problem. A great read – I’ve experienced the phenomenon (where did all these red cars come from?) – but I didn’t know it had a name. Imma be dropping Baader-Meinhoff all over the place 😀

  8. Definitely as my old phone was dying I would notice my phone battery percentage often matched the time eg 35% left and it was 3.50pm. I love saying that when this happens it’s a Sign From The Universe (probably if nothing else that it’s time to charge the phone).

  9. Yes, we see this phenomenon frequently among birdwatchers. For example, when North Americans learn that Red-tailed hawks like to perch on light poles along highways, suddenly they think the hawks are everywhere. The hawks were always there. If anything, bird numbers are decreasing due to human development in many cases…

    By the same token, when a certain bird such as a Northern Cardinal isn’t visiting someone’s yard (maybe they are mating or visiting someone else’s yard for a pattern of time), and the person suddenly notices there are no Cardinals, they sometimes ask authorities if all the Cardinals have disappeared/died, etc.

    Some trends are real: Cooper’s Hawks are learning that backyard bird feeders are where their prey (perching birds) is, and so this hawk is increasing in urban and suburban yards. Data prove the pattern shift

  10. Oh yeah, I’d forgotten about the Baader-Meinhof phenomenon. I didn’t learn it in psych but I read it in all the external reading I did and I like it because it’s applicable, you can notice yourself do it sometimes. When I bought a new car this year, it was used and beggars can’t be choosers so I ended up with a white car. It actually looks pretty cool but white was never my thing and I had never, ever realised how many white cars there were driving around. Suddenly they’re everywhere! I remember going to the supermarket for the first time with said new car thinking at least I’ll be able to spot it a mile off, I’ll be the only one with a bright white tin can. Nuh-uh. Carpark was full of ’em.

    The recency phenomenon wasn’t one I’d heard of before so thank you for writing about it. I can see that in practice, too. That probably happens more than we realise, thinking today’s problems are a new thing when actually they probably go back for centuries. Think that could even apply to environmental stuff? For instance, people mentioning weather extremes and saying that a recent flood is because of global warming in 2021, ignoring how floods have happened many centuries ago and it’s nothing new? 😉 I’m sure the weight of the environment argument is on the severity of such events, but the way I’ve seen some people write and talk about it makes it sound like floods, sunshine or winds are a new phenomenon altogether of the last 20 years. xx

    1. The weather thing is an interesting example, because it seems to go to both extremes, depending on what people already believed. You’ve got the people saying floods are suddenly a thing and it’s due to climate change, and you’ve also got the climate change deniers saying floods have always been a thing, so climate change is not a thing. I guess it comes back to the idea that our perception is likely to be skewed regardless of what we believe, and that’s why data needs to be in the picture too.

  11. This is very interesting. I was first made aware of this thing (although not its name) when I was in my teens and started experiencing a kind of anxiety that I’d never experienced before, which made me really scared of a specific word/sound cluster and I’d always feel a sense of danger whenever someone would say it out loud. Obviously I started hearing people saying it everywhere, even though objectively it’s not an overwhelmingly common word or group of sounds at all. The whole thing was so awful that at some point I seriously started thinking that it must be somehow obvious even to random people that I’m scared of that and they’d say it deliberately in order to torture me. I finally talked about it to my therapist on the phone and it was her who told me about this illusioon being a thing, that pregnant women see everything to do with pregnancy all the time because their brains are on the look out for it. I guess I have quite a strong tendency to look for patterns in various situations so I might be quite prone to this in general.

    1. I wonder if being blind heightens the likelihood of finding patterns in sounds. Sighted people tend to have a strong tendency to find visual patterns, particularly faces, in inanimate objects, like seeing Jesus in toast.

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