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arXiv 2407.00219cs.CLcs.AI

评估大语言模型理由的人类对齐性与模型忠实度

Evaluating Human Alignment and Model Faithfulness of LLM Rationale

University of California, Los Angeles(加州大学洛杉矶分校);Google(谷歌公司)

Mohsen Fayyaz, Fan Yin, Jiao Sun, Nanyun Peng

AI总结:

本文系统比较了基于提示和基于归因的LLM理由生成方法,发现提示式自我解释在人类对齐性和模型忠实度上均不如归因式解释,并指出微调对两类方法影响不同,早期忠实度结论不确定可能源于分类准确率较低。

摘要:

我们研究大语言模型(LLMs)在多大程度上通过理由(rationales)来解释其生成结果——理由是从输入文本中提取的一组token,反映LLMs的决策过程。具体而言,我们系统地研究通过两种方法得到的理由:(1)流行的基于提示(prompting)的方法,即使用提示来引导LLMs生成理由;(2)技术性的基于归因(attribution)的方法,利用注意力或梯度来识别重要token。我们的分析涵盖三个带有标注理由的分类数据集,涉及性能水平各异的任务。尽管基于提示的自我解释被广泛使用,但我们的研究表明,这些解释并不总是像基于归因的解释那样与人类理由“对齐”。更重要的是,微调LLMs以提高分类任务准确率并不会提升基于提示的理由的对齐性。然而,它确实显著改善了基于归因的方法(例如InputXGradient)的对齐性。更为关键的是,我们表明基于提示的自我解释在“忠实度”上也低于基于归因的解释,无法可靠地说明模型的决策过程。为了评估忠实度,与先前排除错误分类样本的研究不同,我们评估所有实例,并考察微调和准确率对对齐性与忠实度的影响。我们的发现表明,早期研究中报告的不确定的忠实度结果可能源于较低的分类准确率。这些发现强调了更严格、更全面地评估LLM理由的重要性。

英文摘要:

We study how well large language models (LLMs) explain their generations through rationales -- a set of tokens extracted from the input text that reflect the decision-making process of LLMs. Specifically, we systematically study rationales derived using two approaches: (1) popular prompting-based methods, where prompts are used to guide LLMs in generating rationales, and (2) technical attribution-based methods, which leverage attention or gradients to identify important tokens. Our analysis spans three classification datasets with annotated rationales, encompassing tasks with varying performance levels. While prompting-based self-explanations are widely used, our study reveals that these explanations are not always as "aligned" with the human rationale as attribution-based explanations. Even more so, fine-tuning LLMs to enhance classification task accuracy does not enhance the alignment of prompting-based rationales. Still, it does considerably improve the alignment of attribution-based methods (e.g., InputXGradient). More importantly, we show that prompting-based self-explanation is also less "faithful" than attribution-based explanations, failing to provide a reliable account of the model's decision-making process. To evaluate faithfulness, unlike prior studies that excluded misclassified examples, we evaluate all instances and also examine the impact of fine-tuning and accuracy on alignment and faithfulness. Our findings suggest that inconclusive faithfulness results reported in earlier studies may stem from low classification accuracy. These findings underscore the importance of more rigorous and comprehensive evaluations of LLM rationales.

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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