When Explanations Lie: Why Many Modified BP Attributions Fail

Fuente: arXiv
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Main Authors: Sixt, Leon, Granz, Maximilian, Landgraf, Tim
Format: Preprint
Published: 2019
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author Sixt, Leon
Granz, Maximilian
Landgraf, Tim
author_facet Sixt, Leon
Granz, Maximilian
Landgraf, Tim
contents Attribution methods aim to explain a neural network's prediction by highlighting the most relevant image areas. A popular approach is to backpropagate (BP) a custom relevance score using modified rules, rather than the gradient. We analyze an extensive set of modified BP methods: Deep Taylor Decomposition, Layer-wise Relevance Propagation (LRP), Excitation BP, PatternAttribution, DeepLIFT, Deconv, RectGrad, and Guided BP. We find empirically that the explanations of all mentioned methods, except for DeepLIFT, are independent of the parameters of later layers. We provide theoretical insights for this surprising behavior and also analyze why DeepLIFT does not suffer from this limitation. Empirically, we measure how information of later layers is ignored by using our new metric, cosine similarity convergence (CSC). The paper provides a framework to assess the faithfulness of new and existing modified BP methods theoretically and empirically. For code see: https://github.com/berleon/when-explanations-lie
format Preprint
id arxiv_https___arxiv_org_abs_1912_09818
institution arXiv
publishDate 2019
record_format arxiv
spellingShingle When Explanations Lie: Why Many Modified BP Attributions Fail
Sixt, Leon
Granz, Maximilian
Landgraf, Tim
Machine Learning
Attribution methods aim to explain a neural network's prediction by highlighting the most relevant image areas. A popular approach is to backpropagate (BP) a custom relevance score using modified rules, rather than the gradient. We analyze an extensive set of modified BP methods: Deep Taylor Decomposition, Layer-wise Relevance Propagation (LRP), Excitation BP, PatternAttribution, DeepLIFT, Deconv, RectGrad, and Guided BP. We find empirically that the explanations of all mentioned methods, except for DeepLIFT, are independent of the parameters of later layers. We provide theoretical insights for this surprising behavior and also analyze why DeepLIFT does not suffer from this limitation. Empirically, we measure how information of later layers is ignored by using our new metric, cosine similarity convergence (CSC). The paper provides a framework to assess the faithfulness of new and existing modified BP methods theoretically and empirically. For code see: https://github.com/berleon/when-explanations-lie
title When Explanations Lie: Why Many Modified BP Attributions Fail
topic Machine Learning
url https://arxiv.org/abs/1912.09818