Pairing Original Text with Meaning-Preserving Rewrites for Sample-Efficient Small-Data Language Model Pretraining

Shaoxiang Wu, Alexander Fraser, Lukas Edman


Abstract
We investigate whether augmenting training data with LLM-generated rewrites can improve performance in small-data language model pretraining. We pair each training sentence with a meaning-preserving rewrite, so that masked tokens can be predicted using both the original and its paired version in the same training window. On FineWeb, we test three rewrite types: *simplification* (shorter and easier), *explanation* (longer and easier), and *paraphrasing* (similar length but harder to read). We also test simplification on OpenStax+BCCampus and Simple Wikipedia. We add a reverse masking curriculum: 7 epochs of whole-word masking (WWM), where entire words are masked instead of individual subword tokens, followed by 3 epochs of standard token-level masking (WWM7-to-Token3). The masking procedure is not rewrite-aware: it does not use alignments between the original sentence and its rewrite. All three FineWeb rewrite types improve EWoK and GLUE-style fine-tuning over source-matched baselines, and simplification improves Entity Tracking across all three sources. The EWoK and GLUE gains concentrate on concept-swap and sentence-pair tasks, suggesting that rewrite pairing especially helps models link meaning across different surface forms. Despite using only one-tenth as much training data, our best model surpasses the official BabyLM 100M GPT-2 baseline on EWoK, Entity Tracking, and GLUE, suggesting that paired rewrite augmentation can improve sample efficiency under a fixed small-data budget.
Anthology ID:
2026.babylm-main.48
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:
611–623
Language:
URL:
https://aclanthology.org/2026.babylm-main.48/
DOI:
Bibkey:
Cite (ACL):
Shaoxiang Wu, Alexander Fraser, and Lukas Edman. 2026. Pairing Original Text with Meaning-Preserving Rewrites for Sample-Efficient Small-Data Language Model Pretraining. In Proceedings of the Second BabyLM Workshop, pages 611–623, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Pairing Original Text with Meaning-Preserving Rewrites for Sample-Efficient Small-Data Language Model Pretraining (Wu et al., BabyLM 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.babylm-main.48.pdf