Are Linguistic and Arithmetic Circuits Dissociated in LLMs?

Riku Kisako, Tatsuki Kuribayashi, Ryohei Sasano


Abstract
Large language models (LLMs) exhibit both knowledge of language, rendered by, for example, grammatical judgment ability, and abilities to perform tasks through language, such as math-word problem solving. Motivated by neurolinguistic studies of their neural dissociation in human brains, in this study, we investigate the overlap of their circuits in large language models (LLMs). Specifically, we examine the overlap and causal effects between the circuits extracted for linguistic and arithmetic tasks, using controlled materials and circuit discovery methods from the mechanistic interpretability field. Our experiments with five LLMs show that circuit similarity is mostly explained by task domains (linguistic vs. arithmetic), rather than by their input and output vocabularies or by the syntactic similarities between natural-language sentences and arithmetic expressions. This finding suggests that LLMs may process linguistic and arithmetic information using largely separate neural circuits, highlighting an ability-based modular organization of circuits within these models.
Anthology ID:
2026.aacl-long.8
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
157–173
Language:
URL:
https://aclanthology.org/2026.aacl-long.8/
DOI:
Bibkey:
Cite (ACL):
Riku Kisako, Tatsuki Kuribayashi, and Ryohei Sasano. 2026. Are Linguistic and Arithmetic Circuits Dissociated in LLMs?. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 157–173, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Are Linguistic and Arithmetic Circuits Dissociated in LLMs? (Kisako et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-long.8.pdf