arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2204.08039cs.CL
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预训练语言模型在Few-Shot微调中的病态

Pathologies of Pre-trained Language Models in Few-shot Fine-tuning

University of Virginia(弗吉尼亚大学);Microsoft Research(微软研究院)

Hanjie Chen, Guoqing Zheng, Ahmed Hassan Awadallah, Yangfeng Ji

摘要:

虽然用很少的例子来适应预训练的语言模型在文本分类上表现出了很好的性能,但人们对性能提升的来源缺乏了解。在这项工作中,我们建议回答这个问题,通过解释适应行为使用事后解释模型预测。通过对解释的特征统计进行建模,我们发现(1)在没有微调的情况下,预先训练的模型(例如BERT和RoBERTa)显示出跨标签的强预测偏差;(2)尽管Few-Shot微调可以减轻预测偏差并展示有希望的预测性能,我们的分析表明,模型通过捕获非任务相关的特征(例如,停止词)或浅数据模式(例如,词汇重叠)来获得性能改进。这些观察结果提醒我们,用更少的例子追求模型性能可能会导致病态的预测行为,这需要对模型预测进行进一步的健全性检查,并在Few-Shot微调中仔细设计模型评估。

英文摘要:

Although adapting pre-trained language models with few examples has shown promising performance on text classification, there is a lack of understanding of where the performance gain comes from. In this work, we propose to answer this question by interpreting the adaptation behavior using post-hoc explanations from model predictions. By modeling feature statistics of explanations, we discover that (1) without fine-tuning, pre-trained models (e.g. BERT and RoBERTa) show strong prediction bias across labels; (2) although few-shot fine-tuning can mitigate the prediction bias and demonstrate promising prediction performance, our analysis shows models gain performance improvement by capturing non-task-related features (e.g. stop words) or shallow data patterns (e.g. lexical overlaps). These observations alert that pursuing model performance with fewer examples may incur pathological prediction behavior, which requires further sanity check on model predictions and careful design in model evaluations in few-shot fine-tuning.

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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