Mechanistic Interpretability for Understanding Language Abilities in Large Language Models: A Survey

Xufeng Duan, Zhaoqian Yao, Xinyu Zhou, Zihao Fu, Beijia Kan, Yibo Wang, Bei Xiao, Hengyuan Zhang, Xuemei Tang, Ercong Nie, Zhenguang Cai


Abstract
Large Language Models (LLMs) exhibit strong performance across language tasks, raising the question of whether this success reflects linguistic abstraction or reliance on surface-level statistical patterns. This survey reviews recent advances in mechanistic interpretability (MI) for analyzing candidate internal mechanisms underlying linguistic competence in LLMs. We trace the shift from model-agnostic analyses to transformer-specific methods and summarize core approaches including probing, neuron- and circuit-level analysis, and causal interventions. Synthesizing empirical findings, we argue that current evidence supports an intermediate view: LLMs appear to use reusable mechanisms for some grammatical behaviors, while these mechanisms remain frequency-conditioned, distributed, and only partially understood. We further review interpretability studies of multilingual models, highlighting evidence for both language-specific and shared representations. Finally, we outline open challenges in scalability, benchmarking, and ethics, and discuss directions toward a more cautious mechanistic account of language in LLMs.
Anthology ID:
2026.findings-emnlp.464
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
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SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
9735–9759
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URL:
https://aclanthology.org/2026.findings-emnlp.464/
DOI:
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Cite (ACL):
Xufeng Duan, Zhaoqian Yao, Xinyu Zhou, Zihao Fu, Beijia Kan, Yibo Wang, Bei Xiao, Hengyuan Zhang, Xuemei Tang, Ercong Nie, and Zhenguang Cai. 2026. Mechanistic Interpretability for Understanding Language Abilities in Large Language Models: A Survey. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 9735–9759, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Mechanistic Interpretability for Understanding Language Abilities in Large Language Models: A Survey (Duan et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.464.pdf