A new study from the Massachusetts Institute of Technology (MIT) suggests that using large language models such as ChatGPT reduces mental effort during writing tasks and may impair future cognitive performance.
Researchers tested a small group of participants who were asked to write essays under three conditions: unaided, using Google Search, and using ChatGPT. Brain activity was monitored with electroencephalography (EEG) to measure cognitive load and engagement.
Results showed that participants working without technology had the highest levels of neural activity, followed by those using search engines, with ChatGPT users showing the least. The AI group also produced essays that were more uniform and less distinctive. When asked to summarize or recall their work afterward, participants who used ChatGPT struggled compared to those who wrote without assistance.
The study also tracked longer-term effects. When subjects switched groups, those moving from “brain-only” work to AI tools demonstrated stronger memory recall and cognitive re-engagement. In contrast, participants who shifted from AI-assisted writing to solo work showed weaker neural connectivity and reduced ability to complete cognitive tasks.
Over a four-month period, researchers concluded that participants who relied on AI performed worse overall at neural, linguistic, and scoring levels. The findings suggest that while AI can strengthen results when used after initial independent thinking, relying on it from the outset can diminish long-term learning skills.
The authors acknowledged the study’s limitations, noting its small sample size and lack of diversity. They emphasized the need for further research as AI use becomes more common in classrooms, workplaces, and everyday life.
“As we demonstrated over the course of four months, the LLM group’s participants performed worse than their counterparts in the brain-only group at all levels: neural, linguistic, [and] scoring,” the paper said.
Researchers warned that widespread reliance on AI could reduce people’s ability to think, summarize, and recall effectively. They also flagged potential risks as search engines increasingly integrate AI-generated results.
