Unpacking Let Alone: Human-Scale Models Generalize to a Rare Construction in Form but not Meaning

Wesley Scivetti, Tatsuya Aoyama, Ethan Wilcox, Nathan Schneider


Abstract
Humans have a remarkable ability to acquire and understand grammatical phenomena that are seen rarely, if ever, during childhood. Recent evidence suggests that language models with human-scale pretraining data may possess a similar ability by generalizing from frequent to rare constructions. However, it remains an open question how widespread this generalization ability is, and to what extent this knowledge extends to meanings of rare constructions, as opposed to just their forms. We fill this gap by testing human-scale transformer language models on their knowledge of both the form and meaning of the (rare and quirky) English Let-Alone construction. To evaluate our LMs we construct a bespoke synthetic benchmark that targets syntactic and semantic properties of the construction. We find that human-scale LMs are sensitive to form, even when related constructions are filtered from the dataset. However, human-scale LMs do not make correct generalizations about Let-Alone’s meaning. These results point to an asymmetry in the current architectures’ sample efficiency between language form and meaning, something which is not present in human language learners.
Anthology ID:
2025.emnlp-main.1399
Volume:
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
EMNLP
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Publisher:
Association for Computational Linguistics
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Pages:
27491–27502
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URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.1399/
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Cite (ACL):
Wesley Scivetti, Tatsuya Aoyama, Ethan Wilcox, and Nathan Schneider. 2025. Unpacking Let Alone: Human-Scale Models Generalize to a Rare Construction in Form but not Meaning. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing, pages 27491–27502, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
Unpacking Let Alone: Human-Scale Models Generalize to a Rare Construction in Form but not Meaning (Scivetti et al., EMNLP 2025)
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https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.1399.pdf
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