A new study from the Massachusetts Institute of Technology (MIT) suggests that regular use of AI writing tools, like ChatGPT, may reduce a person’s ability to think critically. The findings raise concerns about the long-term impact of depending on large language models for school or work, as researchers observed a clear link between ChatGPT use and a decline in critical thinking behavior.
The research, conducted by experts at MIT’s Media Lab, involved 54 adult volunteers who participated in multiple writing sessions.
Participants were divided into three groups: one used ChatGPT to help write a 20-minute essay on philanthropy, another relied on Google Search, and the third completed the task without any assistance, relying only on their thoughts. Each group remained in the same condition for three rounds of writing.
Brain monitoring reveals clear gaps in cognitive effort
Throughout the sessions, all participants wore EEG headsets that monitored brain activity in real-time.
The researchers measured mental effort and engagement while also analyzing the essays using both human scorers and AI language tools. They interviewed participants after each round to assess their experience and memory recall.
The results showed a clear pattern. Those who wrote without any external help demonstrated the highest levels of brain activity, suggesting stronger critical engagement.
MIT researchers found that heavy use of ChatGPT weakens memory, lowers brain activity, and may harm learning by replacing critical thinking… pic.twitter.com/nHvgN6cypO
— Jay Anderson (@TheProjectUnity) June 19, 2025
The Google group showed moderate levels, while the ChatGPT group recorded the lowest brain connectivity. According to the study, these differences were consistent across all three writing sessions.
Follow-up tests confirm lasting effects of earlier ChatGPT use
Months later, 18 of the original volunteers returned for a follow-up session. This time, those who had used ChatGPT in earlier sessions wrote without any support, and vice versa.
The results remained consistent: individuals who had previously relied on ChatGPT showed reduced mental engagement, even when writing independently. Meanwhile, those who had originally worked without help displayed stronger memory and mental focus.
Participant interviews added further context. Many individuals who used ChatGPT reported feeling less connected to the essays they had written. Some struggled to recall or quote from their writing shortly after completing the task.
In contrast, those in the “brain-only” group expressed a stronger sense of ownership and understanding of their work.
The study’s combined findings—from brain monitoring, essay quality, and self-reports—highlight a growing concern in education and the workplace. While tools like ChatGPT offer speed and convenience, researchers warn they may come at the cost of deep thinking and learning.
The MIT team says further research is needed, but the evidence so far suggests a need for caution. As use of AI tools continues to grow, the question of how they shape cognitive skills—especially critical thinking—has become more urgent.