The three-stage RLHF recipe turns a text-completion model into a system optimized for human-preferred answers. It separates response-format learning, preference modeling, and reinforcement-learning optimization. section 1.3 section 1.7
The pipeline proceeds in three connected stages:
- Instruction tuning: fine-tune the base model with next-token prediction on carefully crafted question-and-answer data, teaching it to follow prompts and produce an assistant-style response. section 1.3 section 1.7
- Reward-model training: fine-tune a language model on preference relations among completions so it produces a scalar signal representing which answers people prefer. section 1.3
- Reinforcement-learning optimization: use the instruction-tuned model to generate answers and optimize it against the reward model’s scores. section 1.3 section 1.7
From completion to assistant
A base model that merely completes text first sees high-quality question-and-answer examples. A reward model then learns from competing completions collected across prompts and labelers. Reinforcement learning uses its scalar judgments to improve the resulting answers. section 1.3
RLHF commonly changes response style, tone, and format while also improving benchmark performance. Over-optimization can produce excessive length or chattiness and harm capabilities in other domains. section 1.7
