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Main Authors: Liu, Yingnan, Qiao, Rui, Lee, Mong Li, Hsu, Wynne
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2510.11133
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author Liu, Yingnan
Qiao, Rui
Lee, Mong Li
Hsu, Wynne
author_facet Liu, Yingnan
Qiao, Rui
Lee, Mong Li
Hsu, Wynne
contents Test-time adaptation aims to improve model robustness under distribution shifts by adapting models with access to unlabeled target samples. A primary cause of performance degradation under such shifts is the model's reliance on features that lack a direct causal relationship with the prediction target. We introduce Test-time Adaptation by Causal Trimming (TACT), a method that identifies and removes non-causal components from representations for test distributions. TACT applies data augmentations that preserve causal features while varying non-causal ones. By analyzing the changes in the representations using Principal Component Analysis, TACT identifies the highest variance directions associated with non-causal features. It trims the representations by removing their projections on the identified directions, and uses the trimmed representations for the predictions. During adaptation, TACT continuously tracks and refines these directions to get a better estimate of non-causal features. We theoretically analyze the effectiveness of this approach and empirically validate TACT on real-world out-of-distribution benchmarks. TACT consistently outperforms state-of-the-art methods by a significant margin.
format Preprint
id arxiv_https___arxiv_org_abs_2510_11133
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Test-Time Adaptation by Causal Trimming
Liu, Yingnan
Qiao, Rui
Lee, Mong Li
Hsu, Wynne
Machine Learning
Test-time adaptation aims to improve model robustness under distribution shifts by adapting models with access to unlabeled target samples. A primary cause of performance degradation under such shifts is the model's reliance on features that lack a direct causal relationship with the prediction target. We introduce Test-time Adaptation by Causal Trimming (TACT), a method that identifies and removes non-causal components from representations for test distributions. TACT applies data augmentations that preserve causal features while varying non-causal ones. By analyzing the changes in the representations using Principal Component Analysis, TACT identifies the highest variance directions associated with non-causal features. It trims the representations by removing their projections on the identified directions, and uses the trimmed representations for the predictions. During adaptation, TACT continuously tracks and refines these directions to get a better estimate of non-causal features. We theoretically analyze the effectiveness of this approach and empirically validate TACT on real-world out-of-distribution benchmarks. TACT consistently outperforms state-of-the-art methods by a significant margin.
title Test-Time Adaptation by Causal Trimming
topic Machine Learning
url https://arxiv.org/abs/2510.11133