Cognitive Debt

THE STUPIDITY THRESHOLD - What MIT saw on the EEG when students used ChatGPT — and why the most efficient path to the Stupidity Threshold is the one you’ll never notice you’re walking.

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In June 2025, eight researchers at the MIT Media Lab strapped 32-channel EEG caps onto fifty-four university students and asked them to write SAT essays. One group used ChatGPT. One used Google. One used only their own minds. After four months — three sessions in each group’s assigned condition, then a fourth crossover session where the tools were swapped — the data was clear enough that the lead author, Nataliya Kosmyna, made the unusual decision to publish before peer review. She was afraid policymakers were going to roll out something like “GPT kindergarten” before anyone realized what the technology might do to developing minds.

The headline finding is the one that traveled. Eighty-three percent of the ChatGPT users could not quote a single line of the essay they had just finished writing. But that figure, alarming as it is, is not the part that should keep you up at night. The part that should keep you up at night is what the EEG saw across the rest of the brain.