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arXiv 2402.12366cs.LGcs.AIcs.CL
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对齐大型语言模型的AI反馈的批判性评估

A Critical Evaluation of AI Feedback for Aligning Large Language Models

Stanford University(斯坦福大学);Toyota Research Institute(丰田研究所)

Archit Sharma, Sedrick Keh, Eric Mitchell, Chelsea Finn, Kushal Arora, Thomas Kollar

AI总结:

本文批判性评估了RLAIF范式,发现RL步骤的提升主要源于SFT阶段使用较弱教师模型,而非RL本身;使用强模型(如GPT-4)进行简单SFT即可超越现有RLAIF流程,并提供了机制解释与改进建议。

摘要:

带有AI反馈的强化学习(RLAIF)是一种流行的范式,用于提升强大的预训练语言模型的指令遵循能力。RLAIF首先使用来自教师模型的演示进行监督微调(SFT),然后使用来自评论家模型的反馈,通过强化学习(RL)进一步微调模型。尽管最近流行的开源模型在RL步骤中展示了显著的性能提升,但在本文中,我们质疑这个RL步骤的复杂性对于AI反馈是否真正必要。我们表明,RL步骤的提升几乎完全归因于一种普遍做法,即在SFT数据收集时使用较弱的教师模型(例如GPT-3.5),而用于生成AI反馈的评论家模型(例如GPT-4)更强。具体而言,我们表明使用GPT-4作为教师进行简单的监督微调,其表现优于现有的RLAIF流程。更广泛地说,我们发现RLAIF的收益在不同的基础模型家族、测试时评估协议和评论家模型之间存在显著差异。最后,我们为SFT何时可能优于完整的两步RLAIF流程提供了机制性解释,并提出了使RLAIF在实践中发挥最大作用的建议。

英文摘要:

Reinforcement learning with AI feedback (RLAIF) is a popular paradigm for improving the instruction-following abilities of powerful pre-trained language models. RLAIF first performs supervised fine-tuning (SFT) using demonstrations from a teacher model and then further fine-tunes the model with reinforcement learning (RL), using feedback from a critic model. While recent popular open-source models have demonstrated substantial improvements in performance from the RL step, in this paper we question whether the complexity of this RL step is truly warranted for AI feedback. We show that the improvements of the RL step are virtually entirely due to the widespread practice of using a weaker teacher model (e.g. GPT-3.5) for SFT data collection than the critic (e.g., GPT-4) used for AI feedback generation. Specifically, we show that simple supervised fine-tuning with GPT-4 as the teacher outperforms existing RLAIF pipelines. More generally, we find that the gains from RLAIF vary substantially across base model families, test-time evaluation protocols, and critic models. Finally, we provide a mechanistic explanation for when SFT may outperform the full two-step RLAIF pipeline as well as suggestions for making RLAIF maximally useful in practice.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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