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arXiv 2402.16797cs.CL
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设定时钟:预训练语言模型的时间对齐

Set the Clock: Temporal Alignment of Pretrained Language Models

University of Washington(华盛顿大学);Allen Institute for AI(艾伦人工智能研究所)

Bowen Zhao, Zander Brumbaugh, Yizhong Wang, Hannaneh Hajishirzi, Noah A. Smith

AI总结:

本文研究预训练语言模型的时间混乱问题,提出时间对齐方法,通过构建2000-2023年时间敏感问答数据集并采用提示与微调策略,使模型使用目标年份知识,实验显示对齐后性能最高提升62%,历史时间对齐可达2.8倍。

摘要:

语言模型(LMs)在来自多个时间点的网络文本上训练,通常没有任何明确的时间锚定。本研究调查了预训练语言模型的时间混乱问题,并探索了将其内部知识对齐到目标时间的各种方法,我们称之为“时间对齐”。为此,我们首先自动构建了一个数据集,其中包含2000年至2023年每年2万个时间敏感问题及其答案。基于该数据集,我们通过实验表明,预训练语言模型(例如LLaMa2)尽管具有较近的预训练截止时间(例如2022年),但在回答问题时大多使用较早的知识(例如2019年)。随后,我们开发了从提示到微调的多种方法,使语言模型在回答问题时使用其最新知识,并研究了这种对齐中的各种因素。我们的实验表明,将LLaMa2对齐到2022年可以使其性能根据该年的答案提升高达62%。即使没有明确提及时间信息,这种提升也会出现,这表明在预训练之后对齐模型内部时间感知的可能性。最后,我们发现对齐到历史时间也是可行的,如果将模型微调到2010年,其性能可达到未对齐语言模型的2.8倍。这些发现暗示了语言模型内部知识组织的复杂性以及对其进行适当调优的必要性。

英文摘要:

Language models (LMs) are trained on web text originating from many points in time and, in general, without any explicit temporal grounding. This work investigates the temporal chaos of pretrained LMs and explores various methods to align their internal knowledge to a target time, which we call "temporal alignment." To do this, we first automatically construct a dataset containing 20K time-sensitive questions and their answers for each year from 2000 to 2023. Based on this dataset, we empirically show that pretrained LMs (e.g., LLaMa2), despite having a recent pretraining cutoff (e.g., 2022), mostly answer questions using earlier knowledge (e.g., in 2019). We then develop several methods, from prompting to finetuning, to align LMs to use their most recent knowledge when answering questions, and investigate various factors in this alignment. Our experiments demonstrate that aligning LLaMa2 to the year 2022 can enhance its performance by up to 62% according to that year's answers. This improvement occurs even without explicitly mentioning time information, indicating the possibility of aligning models' internal sense of time after pretraining. Finally, we find that alignment to a historical time is also possible, with up to 2.8$\times$ the performance of the unaligned LM in 2010 if finetuning models to that year. These findings hint at the sophistication of LMs' internal knowledge organization and the necessity of tuning them properly.

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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