通过动态遮盖图像关键区域,实现模型决策的因果可解释性。
Spatial Attention Noise Masking for Causally Sufficient Interpretability

- 用UNet生成稀疏平滑的遮罩,主动干预输入以揭示必要特征。
- 遮蔽后分类准确率接近原始水平,证明解释与原决策一致。
- 适合医疗影像、自动驾驶等需可信决策解释的高风险场景。
我们提出一种新型因果可解释性方法,通过在分类前动态遮蔽输入图像来分析视觉模型决策依据。现有方法多为被动分析,仅提供相关性解释;而主动方法常缺乏对输入特征责任的明确归因。本文构建空间注意力噪声遮罩框架,包含一个UNet风格的遮罩生成器和一个ResNet18编码器-线性分类器,同时处理遮蔽与未遮蔽图像。遮罩被正则化为稀疏且空间平滑,且遮蔽后图像嵌入需保持与原图一致。实验表明,该方法在五个分类任务中仍保持近基线分类性能,有效掩蔽大量图像信息时依然可靠,对背景替换与自然对抗样本具有鲁棒性。定性对比显示其遮罩行为优于当前最优特征归因方法,且能提供强因果解释。
原文摘要 · Abstract (English)
We present a novel causal approach to interpretability for computer vision models that dynamically masks the input image prior to classification. The interpretability of deep learning predictions is critical in high-stakes fields such as medical imaging, security, and autonomous driving. Most interpretability methods are applied passively to already trained models, which typically result in correlational rather than causal explanations. Existing causal interpretability methods are limited to post hoc analysis, weakening the causal claims. Additionally, existing active methods generally lack explanations that explicitly assign responsibility to input features. This work proposes a spatial attention noise masking framework that provides causal explanations about the features sufficient for the prediction. The proposed framework consists of: 1) a UNet-style mask generator, and 2) a Resnet18 encoder and linear classifier that classifies both masked and unmasked versions of an input image. The generated masks are regularized to be sparse and spatially smooth, while masked image embeddings are constrained to remain consistent with embeddings from the corresponding unmasked images. The resulting masks can be interpreted as feature attribution maps that are competitive with related interpretability methods while additionally providing strong causal explanations of model predictions. Quantitative evaluations demonstrate mask faithfulness, near-baseline classification performance across five classification tasks despite substantial masking of image information, and robustness to distribution shifts such as background swapping and natural adversarial examples. Qualitative comparisons further demonstrate mask behavior and competitive interpretability relative to state-of-the-art feature attribution methods.
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