„The frequency illusion” — or why, the moment you notice something new, it suddenly seems to appear everywhere

From the "Our Everyday Mind" series

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It always happens the same way.

You learn about a word, a name, an illness, a song for the first time — something that, the day before, didn't even exist for you. And, in the days right after, that thing seems to appear out of nowhere, everywhere. You read it in an article. You hear it on the radio. Someone mentions it in a completely unexpected conversation, one that has nothing to do with the first time.

What a coincidence, you think.

But it's a coincidence that repeats with a regularity that no longer seems accidental at all.

A letter to a newspaper, on a Sunday in 1994

The story of the name doesn't begin in a laboratory, but in the letters section of an American newspaper.

In 1994, a reader named Terry Mullen sent a letter to the "Bulletin Board" column of the St. Paul Pioneer Press, in Minnesota. His story was simple: he had mentioned, in some conversation, the name of the West German group Baader-Meinhof — the far-left militant organization also known as the Red Army Faction, active in the 1970s. He hadn't heard it in a long time, maybe never with real attention. And yet, in the days immediately after, the name started appearing out of nowhere: in a newspaper article, then in a completely separate discussion, shortly after one another.

Mullen, with humor, named the phenomenon the "Baader-Meinhof Phenomenon" and sent the observation to the column's editor. Other readers immediately recognized the sensation and began sending in their own similar stories, under the same joking name — borrowed from a context that otherwise had nothing to do with psychology. The name caught on, informally, long before anyone in research gave it a rigorous explanation.

It wasn't until 2005 that linguist Arnold Zwicky, a professor at Stanford, wrote on his blog about this type of experience and gave it a name better suited for research: the frequency illusion — a term far less memorable than the name of a West German militant group. But much more precise.

From a newspaper in Minnesota, to pregnancy, the new car, and the word you learned last night

Since then, the phenomenon has been recognized in countless forms, almost identical in structure, no matter how different their content sounds.

The woman who becomes pregnant and suddenly sees pregnant women on every street corner — even though, obviously, the real percentage of pregnant women in the population hasn't changed at all in the last few weeks. The person who buys a certain car model and starts seeing it parked on every street in the neighborhood, as if it had just rolled out of some secret factory, just for them. The person who learns a new word in a foreign language and hears it, a few days later, in three different conversations, on the radio, and on a product label.

This happened to me with the title of a book I'd never read. I saw it once, in passing, on a shelf. The following week it appeared to me three times — on a friend's recommendation list, in a podcast I listened to on the go, on the cover of a magazine flipped through in a waiting room. The book hadn't suddenly decided to be everywhere. I had decided, without realizing it, to recognize it.

Or, more delicately: the person who receives a diagnosis, their own or someone close to them, and suddenly has the impression that everyone is talking about that illness — on television, in conversations between friends, on social media. The world hasn't changed overnight. But the way they look at it has.

None of this is due to any real change in the world. The thing hasn't actually become more frequent. What's changed is much simpler, and much closer to home: our own capacity to notice it.

The filter that switches on without being asked

The explanation Zwicky proposed involves two mechanisms working together, not separately.

The first is selective attention. Every second, the mind is bombarded with far more information than it could ever consciously process — sounds, words, images, seemingly insignificant details. To cope, the brain constantly filters, without consulting us, what deserves attention and what can be left to pass as background. The moment a word or concept becomes, for whatever reason, relevant to us, the filter changes its criteria. What used to pass unnoticed — because it didn't matter — suddenly starts getting through the filter, because now it matters.

The thing doesn't appear more often in the world. It appears more often in our attention.

The second mechanism is confirmation bias. Once we've noticed the coincidence once, the mind begins, without any conscious intention, to look for further confirmation — and it finds it, because every new occurrence seems to reinforce the original theory: see, there it is again.What we don't notice, on the other hand, are all the moments when the thing didn't appear at all — and which, naturally, we have no reason to count.

The two mechanisms feed each other. Selective attention brings the coincidence into the foreground. Confirmation bias then turns it into a pattern.

What easily gets lost in the story

The phenomenon, however, has at least two nuances that easily get lost in the simplified version of the story.

The first is a distinction Zwicky himself drew carefully. There's the frequency illusion — the impression that something appears more often after you first notice it. And there's a related but different one, the recency illusion — the impression that, because you just noticed a word or expression, it must be brand new, when in fact it's been around for a long time; no one had simply been listening for it so closely. The two often combine: you notice something for the first time, assume it's recent, and then see it multiplying everywhere — when really, it had been there all along.

The second nuance comes from Zwicky's own experience as a researcher — and it's all the more interesting because it catches him in his own trap. He and his colleagues, linguists specializing in spoken English, were convinced their friends used a specific colloquial construction extremely often „quotative all”, a phrase used mainly to introduce a reaction or a direct line, as in and I’m all, like…. The conviction seemed obvious to them, based on what they "knew" from listening. When they finally transcribed real conversations rigorously, the actual frequency of the construction turned out to be much lower than they'd imagined — even professional researchers studying the phenomenon had their perception of their own data distorted by heightened attention.

The takeaway is simple, and a little humbling: not even expertise protects against the frequency illusion. At most, it makes us more aware of the risk of falling into it — not immune to it.

It's worth saying, though, that not everything that suddenly seems more frequent is, guaranteed, just an illusion. In medicine, there's even the opposite situation: a doctor who has just studied a rare disease starts recognizing it more often in patients — not because the disease has become more common, but because their attention has gotten better. Here, heightened attention isn't inventing coincidences. It's correcting a previous lack of attention. The line between the two situations isn't always easy to draw — and perhaps that's exactly where a little humility is needed: not everything we notice more often is only in our minds. Sometimes, quite simply, we've finally started to see something that had been there all along, unnoticed.

What might change if you knew

That most "coincidences" of this kind aren't signals from the universe, but from our own attention — which, once directed at something, keeps bringing it to the foreground.

That the thing we noticed hasn't actually become more frequent. Just more visible to us, who, until now, had no reason to remark on it.

That not even the researchers who study this phenomenon are immune to it — a sign that it's not a personal weakness, but a way of functioning common to every mind.

That, every once in a while, it's also worth checking: not everything that suddenly seems omnipresent is only in our heads. Sometimes we've simply, finally, noticed something that deserved attention long ago.

The world is, probably, far more stable than we think. What changes, most of the time, is the light we look at it in. And once attention shifts, the same world suddenly starts to look like a different one.

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