Patterns
๐ŸŽฏ

Reinforcement Learning from Human Feedback(RLHF)

Training AI agents to align with human preferences through reinforcement learning on human feedback

Complexity: highLearning and Adaptation

๐ŸŽฏ 30-Second Overview

Pattern: Three-phase training: SFT โ†’ Reward Model โ†’ PPO optimization with human preference alignment

Why: Aligns AI behavior with human values, improves safety, helpfulness, and reduces harmful outputs

Key Insight: Human preferences > reward model > policy optimization creates scalable alignment mechanism

โšก Quick Implementation

1SFT:Supervised fine-tuning on demonstrations
2Collect:Human preference comparisons
3Train RM:Reward model on preferences
4PPO:Policy optimization with RM rewards
5Evaluate:Human preference win rates
Example: base_model โ†’ sft_model โ†’ preference_data โ†’ reward_model โ†’ aligned_model

๐Ÿ“‹ Do's & Don'ts

โœ…Use diverse, high-quality human preference data
โœ…Apply KL regularization to prevent policy drift
โœ…Monitor reward hacking and Goodhart's law effects
โœ…Use multiple evaluation metrics beyond reward scores
โœ…Implement careful hyperparameter tuning for PPO
โœ…Validate reward model correlation with human judgments
โŒSkip reward model validation on held-out data
โŒUse biased or low-quality preference annotations
โŒIgnore distribution shift in deployment
โŒOptimize purely for reward model scores
โŒUse unstable RL training without safety measures

๐Ÿšฆ When to Use

Use When

  • โ€ข Human preference alignment crucial
  • โ€ข Safety and helpfulness requirements
  • โ€ข Complex subjective quality judgments
  • โ€ข Large-scale deployment with user interaction
  • โ€ข Need for controllable AI behavior

Avoid When

  • โ€ข Simple objective tasks with clear metrics
  • โ€ข Limited human annotation budget
  • โ€ข Real-time inference requirements
  • โ€ข Tasks with well-defined ground truth
  • โ€ข Small-scale or research-only applications

๐Ÿ“Š Key Metrics

Human Preference Win Rate
% preferred over baseline
Reward Model Accuracy
Agreement with human labels
KL Divergence
Policy drift from reference model
Helpfulness Score
Task completion quality
Harmlessness Rate
% safe responses
PPO Training Stability
Reward curve convergence

๐Ÿ’ก Top Use Cases

Conversational AI: Align chatbots for helpful, harmless, honest responses
Content Generation: Optimize creative writing for human preferences
Code Assistants: Improve code quality and safety recommendations
Summarization: Generate summaries matching human quality judgments
Question Answering: Provide accurate, well-formatted answers
Creative Tools: Align AI art/music generation with aesthetic preferences

Reinforcement Learning from Human Feedback

Interactive RLHF training pipeline with human preferences

RLHF Pipeline

Generation
Feedback
Training
Evaluation
Model Version: v1 โ€ข Training Steps: 0

Current Example

Waiting for generation...

Policy Metrics

Average Reward0.250
KL Divergence0.0150
Human Alignment45.0%
Response Quality52.0%

Reward Signals

ppo
-0.200
reward_model
+0.700
human
+0.300
Human Reward Model PPO

Training History

No training examples yet

RLHF Algorithm Overview

Core Process: Generate multiple responses โ†’ Collect human preferences โ†’ Train reward model โ†’ Optimize policy with PPO while maintaining KL constraint.

Key Components: Supervised fine-tuning (SFT), reward modeling from preferences, proximal policy optimization (PPO) with KL penalty.

Human Feedback: Pairwise comparisons, rankings, or direct ratings that teach the model human values and preferences.

Benefits: Aligns model behavior with human values, improves helpfulness and safety, reduces harmful outputs.

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