Exploring Auxiliary Objectives through Multi-Task Learning for Small-Data Language Model Pretraining: A BabyLM 2026 Submission

Alonso Palomino


Abstract
Pretraining optimizes a language model with self-supervised objectives over raw text, shaping the representations later measured by diagnostic evaluations. Masked language modeling (MLM) predicts hidden tokens from context, combining the distributional hypothesis with the cloze task. Less is known about alternative objectives under small data budgets. Using BabyLM 2026’s 10M-token Strict-Small setting, this paper asks whether auxiliary objectives jointly improve grammar, world-knowledge plausibility, entity tracking, and reading prediction, or instead benefit some areas at the expense of others. The experiments compare an MLM-only baseline with several multi-task objective mixtures while holding the corpus, architecture, tokenizer, training budget, and evaluation pipeline fixed. Results are selective: MLM-only is strongest on grammatical minimal-pair judgments, while auxiliary objectives improve entity-state tracking and reading prediction. Within the controlled fast evaluation, single-mask semantic cloze gives the clearest directional world-knowledge plausibility gain; grammar repair does not recover grammatical performance, and broad plausibility classification produces no positive EWoK delta. The central finding is objective-interface alignment: auxiliary objectives transfer most clearly when their loss format resembles the diagnostic interface used at evaluation time. Auxiliary objectives therefore act as targeted steering signals rather than uniform improvements over MLM.
Anthology ID:
2026.babylm-main.38
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:
493–503
Language:
URL:
https://aclanthology.org/2026.babylm-main.38/
DOI:
Bibkey:
Cite (ACL):
Alonso Palomino. 2026. Exploring Auxiliary Objectives through Multi-Task Learning for Small-Data Language Model Pretraining: A BabyLM 2026 Submission. In Proceedings of the Second BabyLM Workshop, pages 493–503, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Exploring Auxiliary Objectives through Multi-Task Learning for Small-Data Language Model Pretraining: A BabyLM 2026 Submission (Palomino, BabyLM 2026)
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PDF:
https://aclanthology.org/2026.babylm-main.38.pdf