On the Faithfulness of Vision Transformer Explanations

Fuente: arXiv
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Auteurs principaux: Wu, Junyi, Kang, Weitai, Tang, Hao, Hong, Yuan, Yan, Yan
Format: Preprint
Publié: 2024
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author Wu, Junyi
Kang, Weitai
Tang, Hao
Hong, Yuan
Yan, Yan
author_facet Wu, Junyi
Kang, Weitai
Tang, Hao
Hong, Yuan
Yan, Yan
contents To interpret Vision Transformers, post-hoc explanations assign salience scores to input pixels, providing human-understandable heatmaps. However, whether these interpretations reflect true rationales behind the model's output is still underexplored. To address this gap, we study the faithfulness criterion of explanations: the assigned salience scores should represent the influence of the corresponding input pixels on the model's predictions. To evaluate faithfulness, we introduce Salience-guided Faithfulness Coefficient (SaCo), a novel evaluation metric leveraging essential information of salience distribution. Specifically, we conduct pair-wise comparisons among distinct pixel groups and then aggregate the differences in their salience scores, resulting in a coefficient that indicates the explanation's degree of faithfulness. Our explorations reveal that current metrics struggle to differentiate between advanced explanation methods and Random Attribution, thereby failing to capture the faithfulness property. In contrast, our proposed SaCo offers a reliable faithfulness measurement, establishing a robust metric for interpretations. Furthermore, our SaCo demonstrates that the use of gradient and multi-layer aggregation can markedly enhance the faithfulness of attention-based explanation, shedding light on potential paths for advancing Vision Transformer explainability.
format Preprint
id arxiv_https___arxiv_org_abs_2404_01415
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the Faithfulness of Vision Transformer Explanations
Wu, Junyi
Kang, Weitai
Tang, Hao
Hong, Yuan
Yan, Yan
Computer Vision and Pattern Recognition
To interpret Vision Transformers, post-hoc explanations assign salience scores to input pixels, providing human-understandable heatmaps. However, whether these interpretations reflect true rationales behind the model's output is still underexplored. To address this gap, we study the faithfulness criterion of explanations: the assigned salience scores should represent the influence of the corresponding input pixels on the model's predictions. To evaluate faithfulness, we introduce Salience-guided Faithfulness Coefficient (SaCo), a novel evaluation metric leveraging essential information of salience distribution. Specifically, we conduct pair-wise comparisons among distinct pixel groups and then aggregate the differences in their salience scores, resulting in a coefficient that indicates the explanation's degree of faithfulness. Our explorations reveal that current metrics struggle to differentiate between advanced explanation methods and Random Attribution, thereby failing to capture the faithfulness property. In contrast, our proposed SaCo offers a reliable faithfulness measurement, establishing a robust metric for interpretations. Furthermore, our SaCo demonstrates that the use of gradient and multi-layer aggregation can markedly enhance the faithfulness of attention-based explanation, shedding light on potential paths for advancing Vision Transformer explainability.
title On the Faithfulness of Vision Transformer Explanations
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2404.01415