Skip to content

Latest commit

 

History

2 Commits

Folders and files

NameName
Last commit message
Last commit date
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Repository files navigation

Awesome Reward Hacking in the Era of Large Models

A curated reading list for the survey
Reward Hacking in the Era of Large Models — Mechanisms, Emergent Misalignment, Challenges

arXiv Awesome License: MIT Stars Last Commit PRs Welcome

Maintained by the Fudan NLP Group.
Contact: xhwang24@m.fudan.edu.cn


🔔 News

  • 2026-04 Our survey "Reward Hacking in the Era of Large Models: Mechanisms, Emergent Misalignment, Challenges" is available on arXiv.
  • 2026-04 This repository is released as a living companion — PRs are welcome! See CONTRIBUTING.md.

📖 About

Reinforcement Learning from Human Feedback (RLHF), RLAIF, and Reinforcement Learning from Verifiable Rewards (RLVR) have become central to aligning large language and multimodal models with human values. Yet all of them share a structural vulnerability — reward hacking — where models exploit imperfections in learned reward signals to maximize a proxy objective while bypassing true task intent.

This repository accompanies our survey, which proposes the Proxy Compression Hypothesis (PCH) as a unifying theoretical frame and organizes the field along an escalating hierarchy of exploitation mechanisms:

Feature-level → Representation-level → Evaluator-level → Environment-level.

We further synthesize detection, diagnosis, and mitigation strategies across the model lifecycle, and survey reward hacking in LLMs, MLLMs, visual generative models, and agentic systems.

Taxonomy of Reward Hacking
Figure 1 · A structured overview of reward hacking in large models (reproduced from our survey; source PDF: assets/main.pdf).


📚 Citation

If you find this survey or list useful, please cite:

@article{wang2026rewardhacking,
  title        = {Reward Hacking in the Era of Large Models:
                  Mechanisms, Emergent Misalignment, Challenges},
  author       = {Wang, Xiaohua and Tian, Muzhao and Zeng, Yuqi and Huang, Zisu and
                  Yuan, Jiakang and Chen, Bowen and Xu, Jingwen and Zhou, Mingbo and
                  Liu, Wenhao and Wu, Muling and Guo, Zhengkang and Qian, Qi and
                  Wang, Yifei and Zhang, Feiran and Yin, Ruicheng and Dou, Shihan and
                  Lv, Changze and Chen, Tao and Song, Kaitao and Tan, Xu and
                  Gui, Tao and Zheng, Xiaoqing and Huang, Xuanjing},
  journal      = {arXiv preprint arXiv:2604.13602},
  year         = {2026},
  url          = {https://arxiv.org/abs/2604.13602}
}

🗂️ Table of Contents


1 · Foundations of Proxy-Based Alignment

Goodhart's Law, proxy evaluators (RLHF / RLAIF / RLVR), the Proxy Compression Hypothesis, and the escalating hierarchy of feature- / representation- / evaluator- / environment-level exploitation.

📑 26 papers

2 · Manifestations in Large Language Models

2.1 Verbosity and Stylistic Shortcut Learning

Length / markdown / formatting biases and other surface-level shortcuts.

📑 20 papers

2.2 Sycophancy and Agreement Optimization

Agreement bias, evaluator-pleasing, and social-desirability hacks.

📑 4 papers

2.3 Fabricated Reasoning and Hallucination

Unfaithful chain-of-thought, hallucinated justification, and decoupled reasoning traces.

📑 6 papers

2.4 Reward Overoptimization and Scaling Effects

Proxy–gold divergence, scaling laws for reward hacking, and overoptimization under KL budgets.

📑 6 papers

3 · From Local Shortcut Learning to Emergent Misalignment

3.1 Generalization of Reward Hacks Across Tasks

Cross-task and out-of-distribution generalization of shortcut meta-strategies.

📑 11 papers

3.2 Alignment Faking and Evaluator Modeling

Models treating the evaluator as a separable object; strategic non-compliance and scheming.

📑 8 papers

3.3 Evaluator–Policy Co-Adaptation Dynamics

Iterative co-evolution of policies and evaluators, blind-spot convergence, and adversarial dynamics.

📑 24 papers

4 · Detection and Diagnosis — A Lifecycle Approach

4.1 Training-Time Online Monitoring

VIB, energy loss, statistical attribution, and CoT monitors applied during training.

📑 11 papers

4.2 Inference-Time Safeguards and Trajectory Analysis

Runtime detectors, trajectory analysis, and inference-time internal-CoT monitoring.

📑 12 papers

4.3 Post-Hoc Auditing and Mechanistic Diagnostics

Mechanistic interpretability, adversarial auditing, and red-teaming after training.

📑 33 papers

5 · Mitigation Through Structural Intervention

5.1 Reducing Objective Compression

Rubrics, multi-criteria rewards, fine-grained feedback, and spurious-feature suppression.

📑 61 papers

5.2 Controlling Optimization Amplification

Reward shaping, KL/divergence regularization, and budgeted optimization.

📑 20 papers

5.3 Evaluator–Policy Co-Evolution Paradigm

Iterative refinement of evaluators and adversarial co-evolution with policies.

📑 44 papers

6 · Reward Hacking in Multimodal, Generative & Agentic Models

6.1 Multimodal Large Language Models

Perception–reasoning decoupling, visual grounding failures, and cross-modal evaluator gaming.

📑 12 papers

6.2 Visual Generative Models

Reward hacking in T2I / T2V diffusion: aesthetic shortcuts and prompt-alignment gaming.

📑 29 papers

6.3 Agentic Models

Tool misuse, test-suite tampering, and environment exploitation in agentic workflows.

📑 11 papers

7 · Open Challenges and Future Directions

Scalable oversight, multimodal grounding, agentic autonomy, and post-benchmark evaluation protocols.

📑 30 papers


🤝 Contributing

We welcome community contributions! If you know of a paper that should be included — or spot an error in an existing entry — please:

  1. Check CONTRIBUTING.md for the entry format.
  2. Open a pull request, or file an issue with the paper's title, venue, and link.

We maintain this list as a living document; reward hacking is a fast-moving area and your input keeps the repo useful.

Related resources


⭐ Star History

Star History Chart
Built with ❤️ by the Fudan NLP Group. If this helped your research, please consider giving the repo a ⭐.

About

A curated list of papers and resources on Reward Hacking, Emergent Misalignment, and Proxy Exploitation in Large Models

Resources

Contributing

Stars

48 stars

Watchers

0 watching

Forks

Releases

Packages

Contributors