Uncertainty-Penalized Reinforcement Learning from Human Feedback with Diverse Reward LoRA Ensembles
On the map: LLM alignment / RLHF / preference optimisation → Reward modeling and RLHF
Abstract (arXiv)
Reinforcement learning from human feedback (RLHF) emerges as a promising paradigm for aligning large language models (LLMs). However, a notable challenge in RLHF is overoptimization, where beyond a certain threshold, the pursuit of higher rewards leads to a decline in human preferences. In this paper, we observe the weakness of KL regularization which is commonly employed in existing RLHF methods to address overoptimization. To mitigate this limitation, we scrutinize the RLHF objective in the offline dataset and propose uncertainty-penalized RLHF (UP-RLHF), which incorporates uncertainty regularization during RL-finetuning. To enhance the uncertainty quantification abilities for reward models, we first propose a diverse low-rank adaptation (LoRA) ensemble by maximizing the nuclear norm of LoRA matrix concatenations. Then we optimize policy models utilizing penalized rewards, determined by both rewards and uncertainties provided by the diverse reward LoRA ensembles. Our experimental results, based on two real human preference datasets, showcase the effectiveness of diverse reward LoRA ensembles in quantifying reward uncertainty. Additionally, uncertainty regularization in UP-RLHF proves to be pivotal in mitigating overoptimization, thereby contributing to the overall performance.
Key facts. Cited by 55 papers in the map (data through 7 Oct 2026). Placed in Reward modeling and RLHF, one of 10 directions in LLM alignment / RLHF / preference optimisation. Builds on 43 of its 54 references that are in the map. First posted on arXiv 30 Dec 2023.
Builds on
43 of 54 references.
Closest ancestors · 14
Same direction, newest first
- 2023Policy Optimization in RLHF: The Impact of Out-of-preference Data17 Dec
- 2023Helping or Herding? Reward Model Ensembles Mitigate but do not Eliminate Reward Hacking14 Dec
- 2023Confronting Reward Model Overoptimization with Constrained RLHF6 Oct
- 2023Reward Model Ensembles Help Mitigate Overoptimization4 Oct
- 2023Pairwise Proximal Policy Optimization: Harnessing Relative Feedback for LLM Alignment30 Sep
- 2023Reinforced Self-Training (ReST) for Language Modeling17 Aug
- 2023DeepSpeed-Chat: Easy, Fast and Affordable RLHF Training of ChatGPT-like Models at All Scales2 Aug
- 2023Open Problems and Fundamental Limitations of Reinforcement Learning from Human Feedback27 Jul
- 2023Direct Preference Optimization: Your Language Model is Secretly a Reward Model29 May
- 2023RRHF: Rank Responses to Align Language Models with Human Feedback without tears11 Apr
- 2022Scaling Laws for Reward Model Overoptimization19 Oct
- 2022Training a Helpful and Harmless Assistant with Reinforcement Learning from Human Feedback12 Apr
2 more
Other references · 29
- 2020Language Models are Few-Shot Learnerscited by 32,199
- 2022Training language models to follow instructions with human feedbackcited by 15,712
- 2017Proximal Policy Optimization Algorithmscited by 14,441
- 2023Llama 2: Open Foundation and Fine-Tuned Chat Modelscited by 12,865
- 2015Dropout as a Bayesian Approximation: Representing Model Uncertainty in Deep Learningcited by 4,416
- 2022OPT: Open Pre-trained Transformer Language Modelscited by 3,464
- 2020Learning to summarize from human feedbackcited by 2,562
- 2015Trust Region Policy Optimizationcited by 2,503
- 2016Asynchronous Methods for Deep Reinforcement Learningcited by 2,218
- 2020Offline Reinforcement Learning: Tutorial, Review, and Perspectives on Open Problemscited by 1,873
- 2022Red Teaming Language Models with Language Modelscited by 983
- 2023A General Theoretical Paradigm to Understand Learning from Human Preferencescited by 906
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- 2019When to Trust Your Model: Model-Based Policy Optimizationcited by 753
- 2019Advantage-Weighted Regression: Simple and Scalable Off-Policy Reinforcement Learningcited by 750
- 2021A Survey of Uncertainty in Deep Neural Networkscited by 675
- 2023Baichuan 2: Open Large-scale Language Modelscited by 664
- 2020MOReL : Model-Based Offline Reinforcement Learningcited by 582
- 2021Understanding Dataset Difficulty with V-Usable Informationcited by 288
- 2023Preference Ranking Optimization for Human Alignmentcited by 283
- 2019Self-Supervised Exploration via Disagreementcited by 263
- 2022Is Reinforcement Learning (Not) for Natural Language Processing: Benchmarks, Baselines, and Building Blocks for Natural Language Policy Optimizationcited by 244
- 2022Offline RL for Natural Language Generation with Implicit Language Q Learningcited by 137
- 2022Pessimistic Bootstrapping for Uncertainty-Driven Offline Reinforcement Learningcited by 125
- 2023Aligning Language Models with Preferences through f-divergence Minimizationcited by 118
- 2022On Reinforcement Learning and Distribution Matching for Fine-Tuning Language Models with no Catastrophic Forgettingcited by 80
- 2023LoRA ensembles for large language model fine-tuningcited by 65
- 2021Revisiting Design Choices in Offline Model-Based Reinforcement Learningcited by 50
- 2023Fine-Tuning Language Models with Advantage-Induced Policy Alignmentcited by 48
- 2022A Review of Uncertainty for Deep Reinforcement Learningcited by 36
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Citing papers per year: 2024: 26; 2025: 14; 2026: 15.
55 papers.
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- 2025Towards Reliable, Uncertainty-Aware Alignment21 Jul 2025
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- 2025Policy Optimized Text-to-Image Pipeline Design27 May 2025
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- 2024Robust Preference Optimization through Reward Model Distillation29 May 2024
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- 2024Scaling Laws for Reward Model Overoptimization in Direct Alignment Algorithmscited by 139
- 2024InfoRM: Mitigating Reward Hacking in RLHF via Information-Theoretic Reward Modelingcited by 76
- 2024Robust Preference Optimization through Reward Model Distillationcited by 67
- 2024Bayesian Reward Models for LLM Alignmentcited by 35
- 2024Overcoming Reward Overoptimization via Adversarial Policy Optimization with Lightweight Uncertainty Estimationcited by 33
- 2024Reward-Robust RLHF in LLMscited by 32
- 2024Eliminating Biased Length Reliance of Direct Preference Optimization via Down-Sampled KL Divergencecited by 29
- 2024Post-hoc Reward Calibration: A Case Study on Length Biascited by 29
- 2024Transforming and Combining Rewards for Aligning Large Language Modelscited by 24
- 2025The Energy Loss Phenomenon in RLHF: A New Perspective on Mitigating Reward Hackingcited by 18
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- 2026A Unifying Lens on Reward Uncertainty in RLHF8 Jun 2026
- 2026Wasserstein Distributionally Robust Regret Optimization for Reinforcement Learning from Human Feedback30 Apr 2026
- 2026RewardUQ: A Unified Framework for Uncertainty-Aware Reward Models27 Feb 2026
- 2026Real-Time Aligned Reward Model beyond Semantics30 Jan 2026
- 2025Ask a Strong LLM Judge when Your Reward Model is Uncertain23 Oct 2025
- 2025Information-Theoretic Reward Modeling for Stable RLHF: Detecting and Mitigating Reward Hacking15 Oct 2025
- 2025Provably Mitigating Corruption, Overoptimization, and Verbosity Simultaneously in Offline and Online RLHF/DPO Alignment7 Oct 2025
- 2025Towards Reliable, Uncertainty-Aware Alignment21 Jul 2025
- 2025Proximalized Preference Optimization for Diverse Feedback Types: A Decomposed Perspective on DPO29 May 2025
- 2025Two Minds Better Than One: Collaborative Reward Modeling for LLM Alignment15 May 2025
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- 2026Reward Modeling for Reinforcement Learning-Based LLM Reasoning: Design, Challenges, and Evaluationcited by 5
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- 2026STAR-GRPO: Canonical Anchoring and Reliability-First Advantages against Representation-Dependent Reward Hackingcited by 0
- 2026STAR-GRPO: Canonical Anchoring and Reliability-First Advantages against Representation-Dependent Reward Hacking29 Sep 2026
- 2026From Curiosity to Caution: Mitigating Reward Hacking for Best-of-N with Pessimism6 Apr 2026
- 2026Reward Modeling for Reinforcement Learning-Based LLM Reasoning: Design, Challenges, and Evaluation10 Feb 2026
- 2025Bayesian Mixture of Experts For Large Language Modelscited by 4
- 2025Bayesian Mixture of Experts For Large Language Models12 Nov 2025
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- 2024Merge, Ensemble, and Cooperate! A Survey on Collaborative Strategies in the Era of Large Language Modelscited by 43
- 2024Uncertainty quantification in fine-tuned LLMs using LoRA ensemblescited by 35
- 2024Comprehensive Overview of Reward Engineering and Shaping in Advancing Reinforcement Learning Applicationscited by 34
- 2024Language Models in Dialogue: Conversational Maxims for Human-AI Interactionscited by 21
- 2024Hallucination Detection in LLMs: Fast and Memory-Efficient Fine-Tuned Modelscited by 15
- 2025Ensemble Learning for Large Language Models in Text and Code Generation: A Surveycited by 8
- 2024Improving Instruction Following in Language Models through Proxy-Based Uncertainty Estimationcited by 6
- 2024Functional-level Uncertainty Quantification for Calibrated Fine-tuning on LLMscited by 5
- 2024Beyond Adapter Retrieval: Latent Geometry-Preserving Composition via Sparse Task Projectioncited by 2
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- 2026TeacherGRPO: Closing the Capacity Gap in Reasoning Distillation via Teacher Alignment27 Sep 2026
- 2026Advantage Scale Calibration Imbalance in Group-Relative Optimization under Low-Variance Rewards: Diagnosis and Bounded Recovery27 Aug 2026
- 2026Reinforcement learning to improve large language model-based automated code compliance systems21 Jun 2026
- 2026Epistemic Uncertainty for Test-Time Discovery11 May 2026
- 2025Policy Optimized Text-to-Image Pipeline Design27 May 2025
- 2025Ensemble Learning for Large Language Models in Text and Code Generation: A Survey13 Mar 2025
- 2024Beyond Adapter Retrieval: Latent Geometry-Preserving Composition via Sparse Task Projection13 Oct 2024
- 2024Functional-level Uncertainty Quantification for Calibrated Fine-tuning on LLMs9 Oct 2024
- 2024Hallucination Detection in LLMs: Fast and Memory-Efficient Fine-Tuned Models4 Sep 2024
- 2024Comprehensive Overview of Reward Engineering and Shaping in Advancing Reinforcement Learning Applications22 Jul 2024
- 2024A Survey on LoRA of Large Language Models8 Jul 2024
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