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In a four-month long study of 54 participants in 2025, MIT researchers found that “LLM users consistently underperformed at neural, linguistic, and behavioral levels,” versus participants who used only their brains or search engines to help write essays. EEG analyses of the participants revealed that AI users basically disabled parts of their brain responsible for creativity and critical thinking when writing with AI.

When the AI participants switched from an LLM to using only their brains in a later essay-writing session, preliminary findings still indicated cognitive debt, which the study’s authors define as “diminished critical inquiry, increased vulnerability to manipulation, [and] decreased creativity.” So even starting with an AI and promising yourself it’s just to get you started is detrimental.

None of the study’s 18 AI users was able to quote from their initial essays, whereas 16/18 brain-only users and 15/18 search engine users were able to.

On top of all this, using AI didn’t even make its users happier. The brain-only participants reported the highest satisfaction with the project.