Revisiting the noun bias: How frequency explains cross-linguistic differences in noun and verb production across early childhood.

Frequency of occurrence is one of the main drivers of children's early vocabularies.However, multiple authors have concluded that it fails to account for one of the most important phenomena in word learningthe order in which children acquire nouns and verbs.Across many languages, there is an early noun bias despite nouns occurring far less frequently than verbs in caregiver speech.In this study we use large-scale caregiver-child corpora and a computational model to reexamine noun and verb learning in English, German, Spanish, and Mandarin.Our results show clear evidence for variations in the strength of the noun bias across languages that can be directly explained by a combination of the number of different nouns and verbs used by caregivers and their sufficient frequency: how often most nouns and verbs need to occur in caregiver speech to be learned.Our findings provide further evidence for frequency shaping early children's language development, in this case mapping onto the relative distributions of nouns and verbs in their mental lexicons. Public Significance StatementThis study suggests that children do not learn nouns before verbs because nouns are conceptually easier to learn.Instead, language analysis reveals children learn words once they hear them a sufficient number of times.Early vocabulary differences across cultures simply reflect how many unique nouns or verbs caregivers use in their everyday speech that exceed this sufficient frequency threshold.