Disentangling Language Understanding and Reasoning Structures in Cross-lingual Chain-of-Thought Prompting

Khanh-Tung Tran, Nguyet-Hang Vu, Barry O’Sullivan, Hoang D. Nguyen


Abstract
Cross-lingual chain-of-thought prompting techniques have proven effective for investigating diverse reasoning paths in Large Language Models (LLMs), especially for low-resource languages. Despite these empirical gains, the mechanisms underlying cross-lingual improvements remain perplexing. This study, therefore, addresses whether the benefits of cross-lingual prompting arise from language-specific reasoning structures intrinsic to each language, or are simply a consequence of improved comprehension through cross-linguistic exposure. We employ neuron intervention and perturbation techniques to analyze and deactivate language-specific reasoning neurons during cross-lingual prompting, leading to performance disparities across languages, up to 27.4%. Our findings disentangle that these neurons are essential for reasoning in their respective languages, but have minimal effect on reasoning in other languages, providing evidence for the existence of language-specific local reasoning structures and guiding the development of more interpretable and effective multilingual AI systems.
Anthology ID:
2025.findings-emnlp.652
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2025
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
12200–12206
Language:
URL:
https://preview.aclanthology.org/author-page-yu-wang-polytechnic/2025.findings-emnlp.652/
DOI:
10.18653/v1/2025.findings-emnlp.652
Bibkey:
Cite (ACL):
Khanh-Tung Tran, Nguyet-Hang Vu, Barry O’Sullivan, and Hoang D. Nguyen. 2025. Disentangling Language Understanding and Reasoning Structures in Cross-lingual Chain-of-Thought Prompting. In Findings of the Association for Computational Linguistics: EMNLP 2025, pages 12200–12206, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
Disentangling Language Understanding and Reasoning Structures in Cross-lingual Chain-of-Thought Prompting (Tran et al., Findings 2025)
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PDF:
https://preview.aclanthology.org/author-page-yu-wang-polytechnic/2025.findings-emnlp.652.pdf
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