What Survives the BabyLM Budget? A Controlled Study of Token Mixers and Generative Objectives

Filipe Laitenberger, Patrick Haller, Jonas Golde, Alan Akbik


Abstract
BabyLM is a pressure test for language-modeling assumptions: which ideas still work when the data budget is closer to a child’s linguistic input than to web-scale pretraining? We use the 2026 English tracks to ask this question in a controlled way, holding the corpus, tokenizer, backbone size family, training schedule, and public evaluation wrapper fixed while varying two token mixers and six objectives. Across 432 completed scale-grid runs on the 10M-word Strict-Small and 100M-word Strict tracks, the strongest result is also the most conservative one. Autoregressive Transformers are the best public-evaluation models at every tested scale, reaching peak fine-tuning macro scores of 64.88 and 66.94 and peak BLiMP scores of 64.70 and 75.13. Masked language modeling is the strongest non-autoregressive baseline. The negative results are informative: Gated DeltaNet improves Entity Tracking but loses grammar and broad transfer, while diffusion and flow objectives show local advantages in probes that rarely survive the official scoring interface. The lesson for BabyLM is not that newer objectives or recurrent mixers are unhelpful, but that small-data gains depend on matching the objective, architecture, sampler, and scorer.
Anthology ID:
2026.babylm-main.7
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:
75–92
Language:
URL:
https://aclanthology.org/2026.babylm-main.7/
DOI:
Bibkey:
Cite (ACL):
Filipe Laitenberger, Patrick Haller, Jonas Golde, and Alan Akbik. 2026. What Survives the BabyLM Budget? A Controlled Study of Token Mixers and Generative Objectives. In Proceedings of the Second BabyLM Workshop, pages 75–92, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
What Survives the BabyLM Budget? A Controlled Study of Token Mixers and Generative Objectives (Laitenberger et al., BabyLM 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.babylm-main.7.pdf