Erase or Hide? Suppressing Spurious Unlearning Neurons for Robust Unlearning

Fuente: arXiv
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Hauptverfasser: Yang, Nakyeong, Kim, Dong-Kyum, Kwon, Jea, Kim, Minsung, Jung, Kyomin, Cha, Meeyoung
Format: Preprint
Veröffentlicht: 2025
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author Yang, Nakyeong
Kim, Dong-Kyum
Kwon, Jea
Kim, Minsung
Jung, Kyomin
Cha, Meeyoung
author_facet Yang, Nakyeong
Kim, Dong-Kyum
Kwon, Jea
Kim, Minsung
Jung, Kyomin
Cha, Meeyoung
contents Large language models trained on web-scale data can memorize private or sensitive knowledge, raising significant privacy risks. Although some unlearning methods mitigate these risks, they remain vulnerable to "relearning" during subsequent training, allowing a substantial portion of forgotten knowledge to resurface. In this paper, we show that widely used unlearning methods cause shallow alignment: instead of faithfully erasing target knowledge, they generate spurious unlearning neurons that amplify negative influence to hide it. To overcome this limitation, we introduce Ssiuu, a new class of unlearning methods that employs attribution-guided regularization to prevent spurious negative influence and faithfully remove target knowledge. Experimental results confirm that our method reliably erases target knowledge and outperforms strong baselines across two practical retraining scenarios: (1) adversarial injection of private data, and (2) benign attack using an instruction-following benchmark. Our findings highlight the necessity of robust and faithful unlearning methods for safe deployment of language models.
format Preprint
id arxiv_https___arxiv_org_abs_2509_22263
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Erase or Hide? Suppressing Spurious Unlearning Neurons for Robust Unlearning
Yang, Nakyeong
Kim, Dong-Kyum
Kwon, Jea
Kim, Minsung
Jung, Kyomin
Cha, Meeyoung
Machine Learning
Large language models trained on web-scale data can memorize private or sensitive knowledge, raising significant privacy risks. Although some unlearning methods mitigate these risks, they remain vulnerable to "relearning" during subsequent training, allowing a substantial portion of forgotten knowledge to resurface. In this paper, we show that widely used unlearning methods cause shallow alignment: instead of faithfully erasing target knowledge, they generate spurious unlearning neurons that amplify negative influence to hide it. To overcome this limitation, we introduce Ssiuu, a new class of unlearning methods that employs attribution-guided regularization to prevent spurious negative influence and faithfully remove target knowledge. Experimental results confirm that our method reliably erases target knowledge and outperforms strong baselines across two practical retraining scenarios: (1) adversarial injection of private data, and (2) benign attack using an instruction-following benchmark. Our findings highlight the necessity of robust and faithful unlearning methods for safe deployment of language models.
title Erase or Hide? Suppressing Spurious Unlearning Neurons for Robust Unlearning
topic Machine Learning
url https://arxiv.org/abs/2509.22263