Hamsa Bastani, O. Bastani, A. Sungu, et al. · 2025 · PNAS 122 Read the source About 1,000 high-school students: unrestricted GPT help raised practice scores by 48% but lowered later exam scores without AI by 17%. A tutor version that gave hints, not answers, avoided the loss. Questions it bears on Does cognitive debt last Who pays the cognitive debt Which safeguards work