Child-Directed Language Does Not Consistently Boost Syntax Learning in Language Models
Summary
The paper tests whether child-directed language (CDL) is truly better material for training language models than text written for adults. This idea was supported by the work of Huebner et al. (2021) on BabyBERTa, but it had been tested only on English and in a single setting. Researchers from the University of Groningen carry out a broader test. They train RoBERTa-based (masked LM) and GPT-2-based (causal LM) models from scratch on CHILDES transcripts. For comparison, the same models are trained on Wikipedia samples of the same size. The languages are English, French and German. The models' syntactic knowledge is evaluated on minimal-pair datasets. The authors also propose FIT-CLAMS, a variant of the CLAMS benchmark in which subjects and verbs are selected with their frequency in both corpora taken into account. The results are complemented by a regression analysis. The main conclusion: CDL does not provide a consistent advantage, and in most cases the Wikipedia-trained models perform better. Without controlling for word frequency, corpus comparisons can be misleading. Therefore, the widespread notion that child-directed speech is especially beneficial for LM training should be reconsidered.
Key points
- Data: only adult utterances addressed to children were taken from CHILDES. For English, the AO-CHILDES split from Huebner et al. was used. Corpus sizes: ≈4.3M tokens (EN), 2.3M (FR) and 3.8M (DE). The Wikipedia corpora are of the same size. Sentences in CHILDES are shorter: about 5.6–6.5 words versus 22–39 in Wikipedia. The lower type/token ratio shows that child-directed speech is highly repetitive.
- Models: both architectures have the same configuration: 8 layers, 8 attention heads, embedding 512, FFN 2048. A separate BPE tokenizer with a vocabulary of 8,192 was trained for each corpus. Training runs for 100,000 steps with AdamW, a warm-up of 40,000 steps and a learning rate of 1e-4. Results are averaged over three random seeds.
- Evaluation: the models are tested on three existing minimal-pair benchmarks, including CLAMS. To these is added the new FIT-CLAMS, balanced for the frequency of subjects and verbs in the training data.
- Limitations acknowledged by the authors: CHILDES is spoken language, while Wikipedia is written, so corpus type is confounded with modality. CDL contains grammatical inconsistencies. The regression covers only simple subject–verb agreement. FIT-CLAMS has no more than 10 lexemes per category (only 7 for French verbs), and these lexemes were selected manually.
- Resource: the code and data are openly published at github.com/fpadovani/childes_vs_wiki.
Topics Language models & pretraining Syntax & grammar formalisms Psycholinguistics & language acquisition
Cite
Cite as Francesca Padovani, Jaap Jumelet, Yevgen Matusevych and Arianna Bisazza. 2025. Child-Directed Language Does Not Consistently Boost Syntax Learning in Language Models. Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing.
@inproceedings{padovani2025child,
title = {{Child-Directed Language Does Not Consistently Boost Syntax Learning in Language Models}},
author = {Francesca Padovani, Jaap Jumelet, Yevgen Matusevych and Arianna Bisazza},
booktitle = {Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing},
year = {2025},
doi = {10.18653/v1/2025.emnlp-main.999},
eprint = {2505.23689},
archivePrefix = {arXiv},
url = {https://doi.org/10.18653/v1/2025.emnlp-main.999}
}References
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