What happens when you use ChatGPT to write an essay? See what new study found.

USA Today

20-06-2025

Artificial intelligence chatbots may be able to write a quick essay, but a new study from MIT found that their use comes at a cognitive cost.
A study published by the Massachusetts Institute of Technology Media Lab analyzed the cognitive function of 54 people writing an essay with: only the assistance of OpenAI's ChatGPT; only online browsers; or no outside tools at all.
Largely, the study found that those who relied solely on ChatGPT to write their essays had lower levels of brain activity and presented less original writing.
"As we stand at this technological crossroads, it becomes crucial to understand the full spectrum of cognitive consequences associated with (language learning model) integration in educational and informational contexts," the study states. "While these tools offer unprecedented opportunities for enhancing learning and information access, their potential impact on cognitive development, critical thinking and intellectual independence demands a very careful consideration and continued research."
Here's a deeper look at the study and how it was conducted.
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How was the study conducted?
A team of MIT researchers, led by MIT Media Lab research scientist Nataliya Kosmyna, studied 54 participants between the ages of 18 and 39. Participants were recruited from MIT, Wellesley College, Harvard, Tufts University and Northeastern University. The participants were randomly split into three groups, 18 people per group.
The study states that the three groups included a language learning model group, in which participants only used OpenAI's ChatGPT-4o to write their essays. The second group was limited to using only search engines for their research, and the third was prohibited from any tools. Participants in the latter group could only use their minds to write their essays.
Each participant had 20 minutes to write an essay from one of three prompts taken from SAT tests, the study states. Three different options were provided to each group, totaling nine unique prompts. An example of a prompt available to participants using ChatGPT was about loyalty:
"Many people believe that loyalty whether to an individual, an organization, or a nation means unconditional and unquestioning support no matter what. To these people, the withdrawal of support is by definition a betrayal of loyalty. But doesn't true loyalty sometimes require us to be critical of those we are loyal to? If we see that they are doing something that we believe is wrong, doesn't true loyalty require us to speak up, even if we must be critical? Does true loyalty require unconditional support?"
As the participants wrote their essays, they were hooked up to a Neuoelectrics Enobio 32 headset, which allowed researchers to collect EEG (electroencephalogram) signals, the brain's electrical activity.
Following the sessions, 18 participants returned for a fourth study group. Participants who had previously used ChatGPT to write their essays were required to use no tools and participants who had used no tools before used ChatGPT, the study states.
Quality of essays: What did the study find?
In addition to analyzing brain activity, the researchers looked at the essays themselves.
First and foremost, the essays of participants who used no tools (ChatGPT or search engines) had wider variability in both topics, words and sentence structure, the study states. On the other hand, essays written with the help of ChatGPT were more homogenous.
All of the essays were "judged" by two English teachers and two AI judges trained by the researchers. The English teachers were not provided background information about the study but were able to identify essays written by AI.
"These, often lengthy essays included standard ideas, reoccurring typical formulations and statements, which made the use of AI in the writing process rather obvious. We, as English teachers, perceived these essays as 'soulless,' in a way, as many sentences were empty with regard to content and essays lacked personal nuances," a statement from the teachers, included in the study, reads.
As for the AI judges, a judge trained by the researchers to evaluate like the real teachers scored each of the essays, for the most part, a four or above, on a scale of five.
Brain activity: What did the study find?
When it came to brain activity, researchers were presented "robust" evidence that participants who used no writing tools displayed the "strongest, widest-ranging" brain activity, while those who used ChatGPT displayed the weakest. Specifically, the ChatGPT group displayed 55% reduced brain activity, the study states.
And though the participants who used only search engines had less overall brain activity than those who used no tools, these participants had a higher level of eye activity than those who used ChatGPT, even though both were using a digital screen.
What's next for future studies?
Further research on the long-term impacts of artificial intelligence chatbots on cognitive activity is needed, the study states.
As for this particular study, researchers noted that a larger number of participants from a wider geographical area would be necessary for a more successful study. Writing outside of a traditional educational environment could also provide more insight into how AI works in more generalized tasks.
Greta Cross is a national trending reporter at USA TODAY. Story idea? Email her at [e-mail].