Systematic Reexamination of Early Verb Dominance: Verbal and Nonverbal Characteristics of Caregiver Input and Their Contribution to Long-Term Language Outcomes

초록

Early language input to infants varies in lexical composition across languages and contexts. For instance, American-English input emphasizes nouns more than verbs, while Mandarin Chinese and Korean inputs provide more verbs than nouns, the difference of which is considered an influential factor in the child's early vocabulary acquisition. Furthermore, a possibility was raised that nonverbal input accompanying child-directed language provides additional support for verb meanings in verb-dominant caregiver input. However, these early verb dominance and support patterns have been derived from a handful of studies that examined very small samples. Thus, we aimed to systematically reexamine the verb dominance pattern in Korean caregiver input, considering both verbal and nonverbal aspects and their relative contributions to long-term vocabulary outcomes using a larger longitudinal sample. From 70 caregiver inputs to their 14- to 20-month-olds (41,349 utterances; 2,186 min, 30 s total), we found that the Korean language supports verb learning through lexical distribution and nonverbal extralinguistic input quality. Both the noun representation ratio and verb proportion positively predicted 54-month vocabulary outcomes, indicating that overall frequency is crucial for long-term vocabulary growth. Differences in caregiver nonverbal input quality between nouns and verbs explained 36-month vocabulary outcomes but did not predict long-term growth. These findings suggest that verbal and nonverbal inputs play different roles in long-term language development and that these might explain why Korean infants demonstrate better comprehension for verbs than nouns early on. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

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