From Puzzle-Solver to Language Model: Recurrent Inductive Bias, Data Scale, and Benchmark Validity in BabyLM

Patrick Haller, Filipe Laitenberger, Jonas Golde, Alan Akbik


Abstract
In the small-data regime of the BabyLM Challenge, a model’s architecture still shapes what it learns. We ask how much an inductive bias toward recurrence helps, and whether current benchmarks can detect that help. Our model adapts the Hierarchical Reasoning Model, a small recurrent puzzle-solver that reuses one shared block many times per token instead of stacking more layers. We make three changes to turn it into a language model: a sequence-mixing layer that can carry order-dependent state, a gate on one of the two connections between its modules, and a tunable number of recurrent cycles. The result matches a parameter-matched GPT-2, and we use it to study three questions. Q1: recurrence buys depth without adding parameters. On a controlled state-tracking task, running more cycles of the same weights tracks longer sequences, even when the extra cycles are added only at inference. Q2: the advantage is largest where data is scarcest. leads GPT-2 on BLiMP at words, ties at , and, trained to convergence, still leads at tokens (out of budget, where data and tokenizer also change). Q3: the benchmark meant to reward state-tracking cannot see it. A null model that never reads the puzzle outscores every trained model on entity_tracking, because 28.5% of its items reveal the answer in the option list and every trained model is at chance on the rest. Gains on that task measure how well a model has learned the frequency of one answer. Because the suite misses a capability we can demonstrate directly, we recommend pairing benchmarks with controlled architectural probes.
Anthology ID:
2026.babylm-main.57
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:
722–734
Language:
URL:
https://aclanthology.org/2026.babylm-main.57/
DOI:
Bibkey:
Cite (ACL):
Patrick Haller, Filipe Laitenberger, Jonas Golde, and Alan Akbik. 2026. From Puzzle-Solver to Language Model: Recurrent Inductive Bias, Data Scale, and Benchmark Validity in BabyLM. In Proceedings of the Second BabyLM Workshop, pages 722–734, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
From Puzzle-Solver to Language Model: Recurrent Inductive Bias, Data Scale, and Benchmark Validity in BabyLM (Haller et al., BabyLM 2026)
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PDF:
https://aclanthology.org/2026.babylm-main.57.pdf