Does AI Make You Dumber? What the Research Actually Says (and My Jury-Duty Counterexample)

Does AI make you dumber? It’s the scariest question in the whole discourse, so let’s be careful with it — because the science is a lot softer than the coverage.

The study everyone cites is MIT Media Lab’s “Your Brain on ChatGPT” (2025). Using EEG during essay writing, it found that brain connectivity scaled inversely with tool use — brain-only writers showed the most engagement, search-engine users moderate, ChatGPT users the least — and, strikingly, most LLM users couldn’t quote a sentence from the essay they’d just “written.” The authors call this accumulating “cognitive debt.” It sounds damning.

But the authors themselves explicitly ask people not to use words like “dumb,” “brain rot,” or “harm” — and for good reason. It’s a non-peer-reviewed preprint with 54 participants (only 18 finished the final session), narrowly about essay-writing. A formal academic Comment argues it’s statistically underpowered (you’d want ~159 people), that lower EEG connectivity doesn’t necessarily mean less thinking — it can mean a shift in strategy or attention — and that there’s no strong evidence the AI actually hurt performance.

The broader work is more measured and, I think, more honest:

• A Microsoft Research + Carnegie Mellon survey of 319 knowledge workers (CHI 2025) found that higher confidence in the AI correlated with less critical thinking, while higher confidence in yourself correlated with more. Crucially, it found AI doesn’t eliminate critical thinking so much as shift it — from doing the task to verifying, integrating, and overseeing the output.
• Gerlich (2025) found a strong negative correlation (r = −0.68) between frequent AI use and critical-thinking scores, with “cognitive offloading” as the mechanism.

Every one of these is correlational and largely self-reported. None of them proves AI causes a decline — and the authors openly note the reverse is plausible: maybe people who lean less on their own thinking are just more likely to lean on AI in the first place.

So my read: there’s a real risk, and it’s specifically the risk of offloading the thinking itself. If you let the machine do the cognition, the cognition atrophies — same as any muscle. But that’s a statement about how you use it, not about the tool.

My own evidence points the other way

Here’s the part I can only speak to personally, so take it as one person’s experience, not a study.

Building with AI has, if anything, reinforced my logical thinking — because the way I do it is the opposite of offloading. Working with AI on a long project is a constant exercise in decomposition: break the problem down, decide what matters, discard what doesn’t, sequence the steps, drive it to completion. You’re not outsourcing the thinking; you’re doing more of it, faster, with a partner who forces you to be explicit.

I noticed it somewhere unexpected: jury duty. Sitting through testimony, I found myself doing the thing I do all day with AI — taking in a flood of information, organizing it, setting aside what wasn’t load-bearing, taking structured notes. In deliberation, while a lot of the room was reaching for the emotional read of the case (which matters too), I was flexing the logical muscle hard, walking the evidence to a conclusion. The same thing shows up at work: troubleshooting a problem when you don’t have enough information, holding the pieces in your head, and walking the issue through to the end.

No AI was in the room for any of that. The habit it built was. That’s the distinction the headlines miss: offload the thinking and it withers; use AI to structure your thinking and it sharpens.

So does AI make you dumber? On the evidence we actually have, the honest answer is: it can, if you let it do your thinking for you — and it can do the opposite if you use it to structure your own. The tool isn’t the variable. You are.

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This is a short take on one thread from a longer piece. The full version covers sycophancy, the environmental cost, jobs, and how to use AI without losing yourself: Optimistic, Eyes Open.