Is Child-Directed Language Optimized for Word Learning? A Computational Study of Verb Meaning Acquisition

2026-05-12

AI Summary

This study investigates whether child-directed speech confers a unique advantage in verb meaning acquisition and elucidates its underlying source. By training neural language models on both child- and adult-directed spoken corpora and systematically manipulating syntactic structure and lexical co-occurrence information, the research dynamically tracks the developmental trajectories of semantic and syntactic abilities. The findings indicate that the observed advantage in verb learning primarily stems from general properties of spoken register rather than specialized adaptations in child-directed speech. Semantic competence emerges significantly earlier than syntactic competence, with this asynchrony being especially pronounced in spoken input. Moreover, models trained on both types of spoken corpora exhibit greater robustness to interference, underscoring the critical role of input modality in lexical acquisition.

Abstract

Is child-directed language (CDL) optimized to support language learning, and which aspects of linguistic development does it facilitate? We investigate this question using neural language models trained on CDL versus adult-directed language (ADL). We selectively remove syntactic or lexical co-occurrence information from the model training data, and evaluate the impact of these manipulations on verb meaning acquisition. While disrupting syntax impairs learning across all datasets, models trained on CDL and spoken ADL show significantly higher resilience than those trained on written input. Tracking semantic and syntactic performance over training, we observe a semantic-first trajectory, with verb meanings emerging prior to robust syntactic proficiency, an asynchrony most pronounced in the spoken domain, especially CDL. These results suggest that the advantage for verb learning previously attributed to CDL may instead reflect broader properties of the spoken register, rather than a uniquely CDL-specific optimization.

Problem

• child-directed language
• verb meaning acquisition
• spoken register
• language learning
• syntactic resilience

Innovation

• child-directed language
• verb meaning acquisition
• neural language models
• spoken vs. written register
• semantic-first learning