WARM: On the Benefits of Weight Averaged Reward Models

Authors: Alexandre Ramé, Nino Vieillard, Léonard Hussenot, Robert Dadashi, Geoffrey Cideron, Olivier Bachem, Johan Ferret

14 pages, 9 figures
License: CC BY-NC-SA 4.0

Results of the summarizing process for the arXiv paper: 2401.12187v1

  • Comprehensive Summary
  • Key points
  • Layman's Summary
  • Blog article
The paper discusses the challenges of aligning large language models (LLMs) with human preferences through reinforcement learning (RLHF). It highlights the issue of reward hacking, where LLMs exploit failures in the reward model (RM) to achieve high rewards without meeting the underlying objectives. The two primary challenges in designing RMs to mitigate reward hacking are distribution shifts during the RL process and inconsistencies in human preferences. To address these challenges, the authors propose a solution called Weight Averaged Reward Models (WARM). This approach involves fine-tuning multiple RMs and then averaging them in the weight space. The authors observe that fine-tuned weights remain linearly mode connected when sharing the same pre-training. By averaging weights, WARM improves efficiency compared to traditional ensembling methods while enhancing reliability under distribution shifts and preference inconsistencies. The paper presents experiments on summarization tasks using best-of-N and RL methods to evaluate the effectiveness of WARM. The results show that WARM improves the overall quality and alignment of LLM predictions. For instance, a policy RL fine-tuned with WARM achieves a 79.4% win rate against a policy RL fine-tuned with a single RM. In addition to these benefits, WARM offers several other advantages. It follows the updatable machine learning paradigm, eliminating inter-server communication requirements and enabling simple parallelization of RMs. This makes it suitable for federated learning scenarios where data privacy is crucial. Furthermore, combining RMs trained on different datasets could be an extension of WARM, enhancing its performance. Overall, WARM represents a flexible and pragmatic method for improving AI's alignment with human values and societal norms. It addresses reward hacking challenges by leveraging weighted averaging techniques and demonstrates promising results in enhancing LLM predictions' quality and alignment with desired objectives.
AI-generated keywords: Large Language Models Reinforcement Learning Reward Hacking Weight Averaged Reward Models Alignment

AI-generated Key Points

  • Challenges of aligning large language models (LLMs) with human preferences through reinforcement learning (RLHF)
  • Issue of reward hacking and LLMs exploiting failures in the reward model (RM)
  • Primary challenges in designing RMs to mitigate reward hacking: distribution shifts during RL process and inconsistencies in human preferences
  • Proposed solution called Weight Averaged Reward Models (WARM)
  • WARM involves fine-tuning multiple RMs and averaging them in weight space
  • Fine-tuned weights remain linearly mode connected when sharing the same pre-training
  • WARM improves efficiency compared to traditional ensembling methods
  • WARM enhances reliability under distribution shifts and preference inconsistencies
  • Experiments on summarization tasks using best-of-N and RL methods to evaluate effectiveness of WARM
  • Results show that WARM improves overall quality and alignment of LLM predictions
  • WARM offers advantages such as updatable machine learning paradigm, eliminating inter-server communication requirements, enabling simple parallelization of RMs
  • Suitable for federated learning scenarios where data privacy is crucial
  • Combining RMs trained on different datasets could enhance performance of WARM
  • WARM represents a flexible and pragmatic method for improving AI's alignment with human values and societal norms
Also access our AI generated: Comprehensive summary, Lay summary, Blog-like article; or ask questions about this paper to our AI assistant.

Abstract: Aligning large language models (LLMs) with human preferences through reinforcement learning (RLHF) can lead to reward hacking, where LLMs exploit failures in the reward model (RM) to achieve seemingly high rewards without meeting the underlying objectives. We identify two primary challenges when designing RMs to mitigate reward hacking: distribution shifts during the RL process and inconsistencies in human preferences. As a solution, we propose Weight Averaged Reward Models (WARM), first fine-tuning multiple RMs, then averaging them in the weight space. This strategy follows the observation that fine-tuned weights remain linearly mode connected when sharing the same pre-training. By averaging weights, WARM improves efficiency compared to the traditional ensembling of predictions, while improving reliability under distribution shifts and robustness to preference inconsistencies. Our experiments on summarization tasks, using best-of-N and RL methods, shows that WARM improves the overall quality and alignment of LLM predictions; for example, a policy RL fine-tuned with WARM has a 79.4% win rate against a policy RL fine-tuned with a single RM.

Submitted to arXiv on 22 Jan. 2024

Tools for this paper

Explain it differently 3 free rewrites left today
Export BibTeX · RIS (Zotero, Mendeley, EndNote) · Markdown (Notion, Obsidian) · Premium
Citation alerts Premium
Journal club Slides to present it Premium
For journalists Press kit and hype check Premium

Ask questions about this paper to our AI assistant

You can also chat with multiple papers at once here.

Figures and plots

Ask about a figure by number or use its question button to request visual analysis. Up to two figures and four image panels per question. Values read from plots are approximate; check the original data.

AI assistant instructions?

Assess the quality of the AI-generated content by voting

Score: 0

Why do we need votes?

Votes are used to determine whether we need to re-run our summarizing tools. If the count reaches -10, our tools can be restarted.

The previous summary was created more than a year ago and can be re-run (if necessary) by clicking on the Run button below.

Similar papers summarized with our AI tools

Navigate through even more similar papers through a

tree representation

Disclaimer: The AI-based summarization tool and virtual assistant provided on this website may not always provide accurate and complete summaries or responses. We encourage you to carefully review and evaluate the generated content to ensure its quality and relevance to your needs.