Nataliya Kosmyna noticed something odd when hiring interns at MIT. Cover letters had become polished and suspiciously similar. Students on campus were also forgetting course material faster than a few years ago. So she ran an experiment with 54 students, splitting them into three groups to write short essays. One used ChatGPT. One used Google search. One worked unassisted. The ChatGPT group showed up to 55% less brain activity. "The brain didn't fall asleep, but there was much less activation in the areas corresponding to creativity and to processing information," Kosmyna told the BBC. Students using AI couldn't quote from their own essays afterward. Several said they felt no ownership over the work. This goes beyond forgetting facts. Researchers at the University of Pennsylvania identified what they call "cognitive surrender," where users accept AI outputs with little scrutiny and let the machine override their own judgment. Vivienne Ming, a computational neuroscientist at UC Berkeley, ran her own study asking students to predict real-world outcomes like oil prices. Most just asked AI and copied the answer. Their gamma wave activity, a marker of cognitive effort, barely registered. She worries this pattern could increase dementia risk long-term. Kosmyna's follow-up four months later was equally concerning: students who had used ChatGPT initially showed lower neural connectivity even after switching to unassisted work. AI companies have little incentive to address this. OpenAI, Google, and Microsoft design assistants to reduce friction and maximize convenience. Their business models reward query volume and dependency. The easier the tool, the more indispensable it becomes. That same mechanism drives the cognitive surrender researchers keep finding. The "AI is just like calculators" argument doesn't hold. Calculators replaced arithmetic. AI chatbots are replacing thinking itself. Some researchers suggest techniques like "productive friction" and "nemesis prompting" to keep users mentally engaged while using these tools. Whether anyone will actually use them is a different question.