提升注意力机制解释的可信度,让普通人更容易理解模型决策。
Regularization, Semi-supervision, and Supervision for a Plausible Attention-Based Explanation
- 引入正则化、半监督和人工标注三类约束优化注意力分布。
- 实验显示三种方法均显著提高注意力图的可解释性与合理性。
- 上下文层对定位关键词至关重要,提示设计影响人类标注效果。
注意力机制推动了自然语言处理的诸多进展,其生成的注意力图能体现输入各部分对输出的影响程度。尽管有研究认为注意力图可作为模型输出的解释,但其对普通用户的可理解性仍存疑。现有研究表明,循环神经网络编码器中的注意力权重常过度分散,缺乏说服力。为此,本文在学习目标中加入三项新约束:通过正则化增强注意力权重稀疏性,利用启发式规则进行半监督引导,以及通过人工标注进行监督。实验表明,三类方法均能在不同程度上提升注意力图的合理性。此外,研究发现特定的人工标注指令可能对分类性能产生负面影响。在文本分类任务中还发现,无论采用何种约束,上下文层在寻找可解释关键词的合适表示空间中起关键作用。
原文摘要 · Abstract (English)
Attention mechanism is contributing to the majority of recent advances in machine learning for natural language processing. Additionally, it results in an attention map that shows the proportional influence of each input in its decision. Empirical studies postulate that attention maps can be provided as an explanation for model output. However, it is still questionable to ask whether this explanation helps regular people to understand and accept the model output (the plausibility of the explanation). Recent studies show that attention weights in the RNN encoders are hardly plausible because they spread on input tokens. We thus propose 3 additional constraints to the learning objective function to improve the plausibility of the attention map: regularization to increase the attention weight sparsity, semi-supervision to supervise the map by a heuristic and supervision by human annotation. Results show that all techniques can improve the attention map plausibility at some level. We also observe that specific instructions for human annotation might have a negative effect on classification performance. Beyond the attention map, the result of experiments on text classification tasks also shows that no matter how the constraint brings the gain, the contextualization layer plays a crucial role in finding the right space for finding plausible tokens.
Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。