mOthello: When Do Cross-Lingual Representation Alignment and Cross-Lingual Transfer Emerge in Multilingual Models?

Tianze Hua, Tian Yun, Ellie Pavlick


Abstract
Many pretrained multilingual models exhibit cross-lingual transfer ability, which is often attributed to a learned language-neutral representation during pretraining. However, it remains unclear what factors contribute to the learning of a language-neutral representation, and whether the learned language-neutral representation suffices to facilitate cross-lingual transfer. We propose a synthetic task, Multilingual Othello (mOthello), as a testbed to delve into these two questions. We find that: (1) models trained with naive multilingual pretraining fail to learn a language-neutral representation across all input languages; (2) the introduction of “anchor tokens” (i.e., lexical items that are identical across languages) helps cross-lingual representation alignment; and (3) the learning of a language-neutral representation alone is not sufficient to facilitate cross-lingual transfer. Based on our findings, we propose a novel approach – multilingual pretraining with unified output space – that both induces the learning of language-neutral representation and facilitates cross-lingual transfer.
Anthology ID:
2024.findings-naacl.103
Volume:
Findings of the Association for Computational Linguistics: NAACL 2024
Month:
June
Year:
2024
Address:
Mexico City, Mexico
Editors:
Kevin Duh, Helena Gomez, Steven Bethard
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1585–1598
Language:
URL:
https://aclanthology.org/2024.findings-naacl.103
DOI:
10.18653/v1/2024.findings-naacl.103
Bibkey:
Cite (ACL):
Tianze Hua, Tian Yun, and Ellie Pavlick. 2024. mOthello: When Do Cross-Lingual Representation Alignment and Cross-Lingual Transfer Emerge in Multilingual Models?. In Findings of the Association for Computational Linguistics: NAACL 2024, pages 1585–1598, Mexico City, Mexico. Association for Computational Linguistics.
Cite (Informal):
mOthello: When Do Cross-Lingual Representation Alignment and Cross-Lingual Transfer Emerge in Multilingual Models? (Hua et al., Findings 2024)
Copy Citation:
PDF:
https://aclanthology.org/2024.findings-naacl.103.pdf