Typology-Guided Adaptation in Multilingual Models

Ndapa Nakashole


Abstract
Multilingual models often treat language diversity as a problem of data imbalance, overlooking structural variation. We introduce the *Morphological Index* (MoI), a typologically grounded metric that quantifies how strongly a language relies on surface morphology for noun classification. Building on MoI, we propose *MoI-MoE*, a Mixture of Experts model that routes inputs based on morphological structure. Evaluated on 10 Bantu languages—a large, morphologically rich and underrepresented family—MoI-MoE outperforms strong baselines, improving Swahili accuracy by 14 points on noun class recognition while maintaining performance on morphology-rich languages like Zulu. These findings highlight typological structure as a practical and interpretable signal for multilingual model adaptation.
Anthology ID:
2025.acl-long.1059
Volume:
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Wanxiang Che, Joyce Nabende, Ekaterina Shutova, Mohammad Taher Pilehvar
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
21819–21835
Language:
URL:
https://preview.aclanthology.org/ingestion-acl-25/2025.acl-long.1059/
DOI:
Bibkey:
Cite (ACL):
Ndapa Nakashole. 2025. Typology-Guided Adaptation in Multilingual Models. In Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 21819–21835, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
Typology-Guided Adaptation in Multilingual Models (Nakashole, ACL 2025)
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PDF:
https://preview.aclanthology.org/ingestion-acl-25/2025.acl-long.1059.pdf