Jul 16, 2026 · 20 min · 11 segments
Our brain doesn't peak once — it peaks many times, for different things, at wildly different ages. You've heard it a thousand times: your brain peaks in your early 20s, then slowly declines. But the…
But if that single peak myth is so widely accepted, what finally proved it wrong? Was there just a sudden breakthrough in brain scans or something?
Actually, no, the breakthrough wasn't a scan at all.
It was a matter of unprecedented scale.
So
Prior to the research, a lot of cognitive studies were fundamentally limited by their sample sizes.
Right, like they'd only test a few people.
Exactly.
Researchers would gather, say, a few hundred university undergraduates, put them in a psychology lab, test them and then maybe compare those results to a small handful of local retirees.
Well, that seems like a flawed comparison right out of the gate.
I mean, a 20 year old college student and an 80 year old retiree grew up in entirely different worlds.
Couldn't the 20 year old just be faster at a cognitive test because they grew up using, you know, rapid fire technology rather than it being a strict matter of biological age?
Yes, that is a crucial point.
And in science, it's known as a cohort effect.
So to get around that, Hartshorne and Jermai knew they needed an absolute ocean of data.
They couldn't just test a few hundred people.
So they built this massive online platform called Games with Words.
Games with Words, like a website.
Yeah.
It functioned as this huge digital testing ground, completely disguising rigorous cognitive assessments as fun, interactive web games.
And their sample size wasn't a few hundred.
They tested nearly 3 million participants.
Wait, 3 million people.
That's staggering.
It totally changed the landscape of cognitive science.
But if that single peak myth is so widely accepted, what finally proved it wrong? Was there just a sudden breakthrough in brain scans or something?
Actually, no, the breakthrough wasn't a scan at all.
It was a matter of unprecedented scale.
So
Prior to the research, a lot of cognitive studies were fundamentally limited by their sample sizes.
Right, like they'd only test a few people.
Exactly.
Researchers would gather, say, a few hundred university undergraduates, put them in a psychology lab, test them and then maybe compare those results to a small handful of local retirees.
Well, that seems like a flawed comparison right out of the gate.
I mean, a 20 year old college student and an 80 year old retiree grew up in entirely different worlds.
Couldn't the 20 year old just be faster at a cognitive test because they grew up using, you know, rapid fire technology rather than it being a strict matter of biological age?
Yes, that is a crucial point.
And in science, it's known as a cohort effect.
So to get around that, Hartshorne and Jermai knew they needed an absolute ocean of data.
They couldn't just test a few hundred people.
So they built this massive online platform called Games with Words.
Games with Words, like a website.
Yeah.
It functioned as this huge digital testing ground, completely disguising rigorous cognitive assessments as fun, interactive web games.
And their sample size wasn't a few hundred.
They tested nearly 3 million participants.
Wait, 3 million people.
That's staggering.
It totally changed the landscape of cognitive science.
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