Brain Scans of ChatGPT Users Reveal Troubling Results
An MIT study analyzing brain activity and recall while using ChatGPT shows a lack of overall brain connectivity while performing an essay writing task, as well as a deficiency in memory recall when compared with control groups.
MIT used EEG readings as well as interviews to score 54 subjects in a variety of brain experiments focused on the task of writing an essay. Subjects were divided into three groups based on the tools they were allowed to use: an LLM (large language model) group, a Search Engine group, and a Brain-only group. Participants in the LLM group were restricted to using OpenAI's GPT-4o (ChatGPT) as their sole resource of information for the essay writing task.
Subjects were then directed to write an essay as readings were taken of their brain. Afterward, interviews were given to each participant. This was then repeated three times for each subject. Researchers then reversed the tools of the LLM group and the Brain-only group for a fourth and final essay.
The results were startling. According to the researchers, “Brain connectivity systematically scaled down with the amount of external support: the Brain‑only group exhibited the strongest, widest‑ranging networks, Search Engine group showed intermediate engagement, and LLM assistance elicited the weakest overall coupling.”
In addition, memory recall was similarly poor for those who used LLM as 83.3% of ChatGPT users couldn’t quote from essays they wrote minutes earlier.
“Quoting accuracy was significantly different across experimental conditions. In the LLM‑assisted group, 83.3 % of participants failed to provide a correct quotation, whereas only 11.1 % in both the Search‑Engine and Brain‑Only groups encountered the same difficulty.” (Pg. 36)
83.3% of ChatGPT users couldn't quote from essays they wrote minutes earlier.
— Alex Vacca (@itsalexvacca) June 18, 2025
Let that sink in.
You write something, hit save, and your brain has already forgotten it because ChatGPT did the thinking. pic.twitter.com/14bKDCDLF5
One of the primary concerns which emerged from this study is the effect of what researchers term “cognitive debt”. This refers to when repeated reliance on external systems like LLMs replaces the effortful cognitive processes required for independent thinking.
“Cognitive debt defers mental effort in the short term but results in long-term costs, such as diminished critical inquiry, increased vulnerability to manipulation, decreased creativity.” (Pg. 141)
A shortened summary of the findings can be accessed at BrainOnLLM.com. The full 206-page preprint of the study can be found here.