Feeding BabyLMs Macaroni: Code-Switching Curricula Cause Cross-Lingual Convergence

Dries Rooryck, Alexander Dazhen Cai, Yonatan Belinkov, David Alvarez-Melis, Kianté Brantley


Abstract
Children in multilingual communities often code-switch, using multiple languages in a single utterance. Can we induce cross-lingual alignment in language models by training on code-switched text? We pretrain small decoder-only transformers on two 100M-word multilingual corpora: a base corpus formed by mixing the English, Dutch, and Chinese BabyBabelLM datasets, and a corpus generated from it by inserting word- and sentence-level code-switching using an LLM. We find that training on code-switched data aligns the representations of parallel text, particularly across different scripts, and that this alignment persists through training on monolingual documents. Under a learning curriculum that progresses from word-level code-switching, to sentence-level code-switching, to monolingual documents, models trained on code-switched data outperform baselines trained without it on the BabyLM evaluation suite. Our work characterizes code-switching curriculum learning as an effective data augmentation method for multilingual pretraining. We release our code, data, and models at https://github.com/drooryck/multilingual-macaroni.
Anthology ID:
2026.babylm-main.59
Volume:
Proceedings of the Second BabyLM Workshop
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Leshem Choshen, Ryan Cotterell, Mustafa Omer Gul, Jaap Jumelet, Tal Linzen, Aaron Mueller, Suchir Salhan, Raj Sanjay Shah, Alex Warstadt, Ethan Gotlieb Wilcox
Venues:
BabyLM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
750–766
Language:
URL:
https://aclanthology.org/2026.babylm-main.59/
DOI:
Bibkey:
Cite (ACL):
Dries Rooryck, Alexander Dazhen Cai, Yonatan Belinkov, David Alvarez-Melis, and Kianté Brantley. 2026. Feeding BabyLMs Macaroni: Code-Switching Curricula Cause Cross-Lingual Convergence. In Proceedings of the Second BabyLM Workshop, pages 750–766, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Feeding BabyLMs Macaroni: Code-Switching Curricula Cause Cross-Lingual Convergence (Rooryck et al., BabyLM 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.babylm-main.59.pdf