COSMIC: Generalized Refusal Direction Identification in LLM Activations

Vincent Siu, Nicholas Crispino, Zihao Yu, Sam Pan, Zhun Wang, Yang Liu, Dawn Song, Chenguang Wang


Abstract
Large Language Models encode behaviors like refusal within their activation space, but identifying these behaviors remains challenging. Existing methods depend on predefined refusal templates detectable in output tokens or manual review. We introduce **COSMIC** (Cosine Similarity Metrics for Inversion of Concepts), an automated framework for direction selection that optimally identifies steering directions and target layers using cosine similarity, entirely independent of output text. COSMIC achieves steering effectiveness comparable to prior work without any prior knowledge or assumptions of a model’s refusal behavior such as the use of certain refusal tokens. Additionally, COSMIC successfully identifies refusal directions in adversarial scenarios and models with weak safety alignment, demonstrating its robustness across diverse settings.
Anthology ID:
2025.findings-acl.1310
Volume:
Findings of the Association for Computational Linguistics: ACL 2025
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Wanxiang Che, Joyce Nabende, Ekaterina Shutova, Mohammad Taher Pilehvar
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
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Pages:
25534–25553
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URL:
https://preview.aclanthology.org/display_plenaries/2025.findings-acl.1310/
DOI:
Bibkey:
Cite (ACL):
Vincent Siu, Nicholas Crispino, Zihao Yu, Sam Pan, Zhun Wang, Yang Liu, Dawn Song, and Chenguang Wang. 2025. COSMIC: Generalized Refusal Direction Identification in LLM Activations. In Findings of the Association for Computational Linguistics: ACL 2025, pages 25534–25553, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
COSMIC: Generalized Refusal Direction Identification in LLM Activations (Siu et al., Findings 2025)
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PDF:
https://preview.aclanthology.org/display_plenaries/2025.findings-acl.1310.pdf