BLiSS: Evaluating Bilingual Learner Competence in Second Language Small Language Models

Yuan Gao, Suchir Salhan, Andrew Caines, Paula Buttery, Weiwei Sun


Abstract
Cross-lingual extensions of the BabyLM Shared Task beyond English incentivise the development of Small Language Models that simulate a much wider range of language acquisition scenarios, including code-switching, simultaneous and successive bilingualism and second language acquisition. However, to our knowledge, there is no benchmark of the formal competence of cognitively-inspired models of L2 acquisition, or L2LMs. To address this, we introduce a Benchmark of Learner Interlingual Syntactic Structure (BLiSS). BLiSS consists of 1.5M naturalistic minimal pairs dataset derived from errorful sentence–correction pairs in parallel learner corpora. These are systematic patterns –overlooked by standard benchmarks of the formal competence of Language Models – which we use to evaluate L2LMs trained in a variety of training regimes on specific properties of L2 learner language to provide a linguistically-motivated framework for controlled measure of the interlanguage competence of L2LMs.
Anthology ID:
2025.babylm-main.13
Volume:
Proceedings of the First BabyLM Workshop
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Lucas Charpentier, Leshem Choshen, Ryan Cotterell, Mustafa Omer Gul, Michael Y. Hu, Jing Liu, Jaap Jumelet, Tal Linzen, Aaron Mueller, Candace Ross, Raj Sanjay Shah, Alex Warstadt, Ethan Gotlieb Wilcox, Adina Williams
Venue:
BabyLM
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
160–174
Language:
URL:
https://preview.aclanthology.org/ingest-emnlp/2025.babylm-main.13/
DOI:
Bibkey:
Cite (ACL):
Yuan Gao, Suchir Salhan, Andrew Caines, Paula Buttery, and Weiwei Sun. 2025. BLiSS: Evaluating Bilingual Learner Competence in Second Language Small Language Models. In Proceedings of the First BabyLM Workshop, pages 160–174, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
BLiSS: Evaluating Bilingual Learner Competence in Second Language Small Language Models (Gao et al., BabyLM 2025)
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PDF:
https://preview.aclanthology.org/ingest-emnlp/2025.babylm-main.13.pdf