You'll start noticing this effect everywhere
September 22, 2025 by
Max van IJsselmuiden
This blog post is about frequency illusion, sometimes referred to as the Baader-Meinhof phenomenon.
My friend said to me the other day: "I was talking about buying a house and potentially moving to Spain. Then I opened up my phone, and the first ad I saw was for a house. The second ad I saw was for a trip to Spain — would you believe it?!"
This is not the first time someone has mentioned a story like this to me. Of course, part of this is due to the scarily accurate profiling of ad companies, but a huge part to this is due to our own brain. We're experiencing frequency illusion.
Frequency illusion is a cognitive bias in which we notice a specific concept more frequently after recently becoming aware of said concept. I've recognised this particular phenomenon in real-life so often to the point where I've decided to write about this.
The funny thing is, if this is the first time you've read about this effect, you'll be able to recognise frequency illusion when it is happening to you — thus experiencing the frequency illusion effect for the concept of frequency illusion. Still with me?
This effect is also known as the Baader-Meinhof phenomenon — which is actually a West German terrorist group from the 1970s. A newspaper reader encountered the Baader-Meinhof name twice within 24 hours, then started noticing the name more frequently.
A personal example for me would be the term 'guerrilla usability testing', which is basically a do-it-yourself approach for a user test. Given the constraints of time on money in the 'real world' as opposed to the 'ideal world' where most design frameworks assume we have all the time and resources we need, I've always been keen on 'quick and dirty' user testing.
For me, this meant testing prototypes with a coworker, family member or a friend. It's a great way to cut out the time-consuming parts of testing, and far more preferable than not testing at all.
The term 'guerrilla' comes from the military tactics, where 'guerrilla warfare' is warfare fought by irregulars in fast-moving and small-scale actions. Guerrilleros were Spanish and Portuguese 'irregulars' during the Peninsular War.
Anyway, I've learned about 'guerrilla' no less than one week ago and I've started recognising the term in design blogs ever since. Frequency illusion would suggest that this effect is happening more often than it actually is. This phenomenon can be explained via two psychological effects: selective attention and confirmation bias.
Selective attention refers to focusing on specific information while ignoring distractions. Selective attention directs focus to information we are looking for; having recently learned of a new concept. As Sheena Iyengar writes in 'The Art of Choosing', a great book which I'm reading right now:
"Humans do, indeed, have two interconnected and yet distinct systems for processing information. (...) The first, which we'll call the automatic system, operates quickly, effortlessly, and subconsciously. (...) In contrast, the reflective system, driven not by raw sensation but by logic and reason, is one that we have to turn on and tune into.”
Sheena Iyengar, ‘The Art of Choosing’, page 107
Selective attention happens mostly in the automatic part of our brain. When reading about 'guerrilla' I made the connection to something I've always done, but didn't know it had a name for it, thus focusing and selecting on the word 'guerrilla' and therefore learning a new concept.
Confirmation bias refers to the tendency of seeking evidence which confirms our beliefs, while overlooking evidence of the contrary. By focusing on the word 'guerrilla', I noticed it more, confirming to me I'm 'not the only one' that uses guerrilla testing and appreciates it for its value. Now, I recognise the term everywhere.
The effect is visible everywhere. In marketing, companies deliberately create initial exposure knowing consumers will then notice their products more frequently. In medicine, rare conditions get overlooked due to unfamiliarity. Start house hunting and you'll see 'for sale' signs everywhere. When car shopping, research a specific car and half of the vehicles on the road seem to be that car.
Recognising frequency illusion can help you make better decisions. When you notice something appearing "everywhere," pause and ask: "Am I seeing this more because I'm looking for it, or because it's actually more common?"
And now that you know about it, you'll probably start recognising it... more frequently.
Did you like this post?
Older
August 11, 2025
The widespread trust in AI chatbots as all-knowing oracles is a dangerous misunderstanding of what they actually are. Large Language Models are sophisticated pattern-matching tools, not truth machines, a critical distinction defining how we should use them.
Want to stay tuned?
You'll start noticing this effect everywhere
September 22, 2025 by
Max van IJsselmuiden
This blog post is about frequency illusion, sometimes referred to as the Baader-Meinhof phenomenon.
My friend said to me the other day: "I was talking about buying a house and potentially moving to Spain. Then I opened up my phone, and the first ad I saw was for a house. The second ad I saw was for a trip to Spain — would you believe it?!"
This is not the first time someone has mentioned a story like this to me. Of course, part of this is due to the scarily accurate profiling of ad companies, but a huge part to this is due to our own brain. We're experiencing frequency illusion.
Frequency illusion is a cognitive bias in which we notice a specific concept more frequently after recently becoming aware of said concept. I've recognised this particular phenomenon in real-life so often to the point where I've decided to write about this.
The funny thing is, if this is the first time you've read about this effect, you'll be able to recognise frequency illusion when it is happening to you — thus experiencing the frequency illusion effect for the concept of frequency illusion. Still with me?
This effect is also known as the Baader-Meinhof phenomenon — which is actually a West German terrorist group from the 1970s. A newspaper reader encountered the Baader-Meinhof name twice within 24 hours, then started noticing the name more frequently.
A personal example for me would be the term 'guerrilla usability testing', which is basically a do-it-yourself approach for a user test. Given the constraints of time on money in the 'real world' as opposed to the 'ideal world' where most design frameworks assume we have all the time and resources we need, I've always been keen on 'quick and dirty' user testing.
For me, this meant testing prototypes with a coworker, family member or a friend. It's a great way to cut out the time-consuming parts of testing, and far more preferable than not testing at all.
The term 'guerrilla' comes from the military tactics, where 'guerrilla warfare' is warfare fought by irregulars in fast-moving and small-scale actions. Guerrilleros were Spanish and Portuguese 'irregulars' during the Peninsular War.
Anyway, I've learned about 'guerrilla' no less than one week ago and I've started recognising the term in design blogs ever since. Frequency illusion would suggest that this effect is happening more often than it actually is. This phenomenon can be explained via two psychological effects: selective attention and confirmation bias.
Selective attention refers to focusing on specific information while ignoring distractions. Selective attention directs focus to information we are looking for; having recently learned of a new concept. As Sheena Iyengar writes in 'The Art of Choosing', a great book which I'm reading right now:
"Humans do, indeed, have two interconnected and yet distinct systems for processing information. (...) The first, which we'll call the automatic system, operates quickly, effortlessly, and subconsciously. (...) In contrast, the reflective system, driven not by raw sensation but by logic and reason, is one that we have to turn on and tune into.”
Sheena Iyengar, ‘The Art of Choosing’, page 107
Selective attention happens mostly in the automatic part of our brain. When reading about 'guerrilla' I made the connection to something I've always done, but didn't know it had a name for it, thus focusing and selecting on the word 'guerrilla' and therefore learning a new concept.
Confirmation bias refers to the tendency of seeking evidence which confirms our beliefs, while overlooking evidence of the contrary. By focusing on the word 'guerrilla', I noticed it more, confirming to me I'm 'not the only one' that uses guerrilla testing and appreciates it for its value. Now, I recognise the term everywhere.
The effect is visible everywhere. In marketing, companies deliberately create initial exposure knowing consumers will then notice their products more frequently. In medicine, rare conditions get overlooked due to unfamiliarity. Start house hunting and you'll see 'for sale' signs everywhere. When car shopping, research a specific car and half of the vehicles on the road seem to be that car.
Recognising frequency illusion can help you make better decisions. When you notice something appearing "everywhere," pause and ask: "Am I seeing this more because I'm looking for it, or because it's actually more common?"
And now that you know about it, you'll probably start recognising it... more frequently.
Did you like this post?
Older
August 11, 2025
The widespread trust in AI chatbots as all-knowing oracles is a dangerous misunderstanding of what they actually are. Large Language Models are sophisticated pattern-matching tools, not truth machines, a critical distinction defining how we should use them.
Want to stay tuned?