OpenAI's o1 introduces visible chain-of-thought reasoning
A model trained to think longer before answering jumps from 13 percent to 83 percent on a math test
Quick facts
- Institution
- OpenAI
- Method
- Reinforcement learning on chain-of-thought reasoning
- Benchmark
- 83% on IMO qualifying exam vs 13% for GPT-4o
What happened
OpenAI released o1-preview and o1-mini, describing them as a new series of models trained with reinforcement learning to work through a chain of thought before producing a final answer, rather than generating a response immediately as prior GPT models did. Through this training process, the model learned to break difficult problems into smaller steps, try alternative approaches when one path stalled, and recognize and correct its own errors, spending more computation at answer time on harder problems. On a qualifying exam for the International Mathematical Olympiad, OpenAI reported that its existing GPT-4o model correctly solved only 13 percent of problems, while the new reasoning model scored 83 percent. OpenAI deliberately kept the model's internal chain of thought hidden from users, citing both safety monitoring and competitive concerns, and reset its model-naming scheme to '1' to mark what it described as a new level of capability distinct from the GPT series.
Why it matters
o1 established test-time compute, letting a model think longer on harder problems, as a second scaling dimension alongside the training-time scaling that had driven progress from GPT-2 through GPT-4, shifting where AI labs began directing their heaviest computational investment.
How we know
OpenAI's own announcement and companion technical post document the training method and the reported math-olympiad scores directly; Georgetown's Center for Security and Emerging Technology, an independent policy research institute, corroborates the same reasoning-based training approach and its significance for future scaling strategy.
Sources
- OpenAI. Introducing OpenAI o1-preview · Primary source (author-declared)openai.com · Cited as a "primary" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
- Center for Security and Emerging Technology, Georgetown University. OpenAI's New Reasoning Model and the Next Stage in AI Development · Reputable sourcecset.georgetown.edu · The domain "cset.georgetown.edu" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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