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arXiv 2402.17124cs.CL
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Fact-and-Reflection (FaR) 提升大型语言模型的置信度校准

Fact-and-Reflection (FaR) Improves Confidence Calibration of Large Language Models

Tencent AI Lab(腾讯AI实验室);Carnegie Mellon University(卡内基梅隆大学)

Xinran Zhao, Hongming Zhang, Xiaoman Pan, Wenlin Yao, Dong Yu, Tongshuang Wu, Jianshu Chen

AI总结:

本文研究提示策略对 LLM 置信度校准的影响,提出两阶段 Fact-and-Reflection (FaR) 提示,通过先引出事实再反思作答,显著降低校准误差并支持检索增强。

摘要:

对于 LLM 而言,要值得信赖,其置信度水平应当与其实际性能良好校准。尽管如今 LLM 的性能会受到提示词显著影响已是常识,但在通过提示引导 LLM 时的置信度校准仍未得到充分研究。本文探讨不同提示策略如何影响 LLM 的置信度校准,以及如何改进这种校准。我们在问答场景中对六种提示方法进行了大量实验,并观察到:尽管这些方法有助于改善预期的 LLM 校准,但它们也会导致 LLM 在回答某些样本时过度自信。受人类认知启发,我们提出 Fact-and-Reflection (FaR) 提示,通过两个步骤改善 LLM 校准。首先,FaR 从 LLM 中引出与输入提示相关的已知“事实”;随后,它要求模型对这些事实进行“反思”,以生成最终答案。实验表明,FaR 提示实现了显著更好的校准;在我们的多用途 QA 任务上,它将 Expected Calibration Error(期望校准误差)降低了 23.5%。值得注意的是,FaR 提示甚至激发了模型在置信度较低的场景中用语言表达担忧的能力,这有助于触发检索增强,以解决这些更困难的样本。

英文摘要:

For a LLM to be trustworthy, its confidence level should be well-calibrated with its actual performance. While it is now common sense that LLM performances are greatly impacted by prompts, the confidence calibration in prompting LLMs has yet to be thoroughly explored. In this paper, we explore how different prompting strategies influence LLM confidence calibration and how it could be improved. We conduct extensive experiments on six prompting methods in the question-answering context and we observe that, while these methods help improve the expected LLM calibration, they also trigger LLMs to be over-confident when responding to some instances. Inspired by human cognition, we propose Fact-and-Reflection (FaR) prompting, which improves the LLM calibration in two steps. First, FaR elicits the known "facts" that are relevant to the input prompt from the LLM. And then it asks the model to "reflect" over them to generate the final answer. Experiments show that FaR prompting achieves significantly better calibration; it lowers the Expected Calibration Error by 23.5% on our multi-purpose QA tasks. Notably, FaR prompting even elicits the capability of verbally expressing concerns in less confident scenarios, which helps trigger retrieval augmentation for solving these harder instances.

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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