Peer reviewed
InstructGPT: Training LMs to Follow Instructions with Human Feedback
Labelers wrote demonstrations to supervise-fine-tune GPT-3, then ranked model outputs to train a reward model, and PPO optimized the policy against that reward. Outputs from the 1.3B InstructGPT model were preferred to the 175B GPT-3's despite being about 100x smaller, with gains in truthfulness and reductions in toxic generation. The three-stage SFT-then-reward-model-then-PPO recipe became the standard alignment pipeline behind instruction-following chat models.