Previous research on the effects of word-level factors on lexical acquisition has shown that frequency and concreteness are most important. Here, we investigate CDI data from 1,030 Dutch children, collected with the short form of the Dutch CDI, to address (i) how word-level factors predict lexical acquisition, once child-level factors are controlled, (ii) whether effects of these word-level factors vary with word class and age, and (iii) whether any interactions with age are due to differences in receptive vocabulary. Mixed-effects regressions yielded effects of frequency and concreteness, but not of word class and phonological factors (e.g., word length, neighborhood density). The effect of frequency was stronger for nouns than predicates. The effects of frequency and concreteness decreased with age, and were not explained by differences in vocabulary knowledge. These findings extend earlier results to Dutch, and indicate that effects of age are not due to increases in vocabulary knowledge.

Is noun dominance in early lexical acquisition a widespread or a language-specific phenomenon? Thirty Singaporean bilingual English–Mandarin learning toddlers and their mothers were observed in a mother-child play interaction. For both English and Mandarin, toddlers’ speech and reported vocabulary contained more nouns than verbs across book reading and toy playing. In contrast, their mothers’ speech contained more verbs than nouns in both English and Mandarin but differed depending on the context of the interaction. Although toddlers demonstrated a noun bias for both languages, the noun bias was more pronounced in English than in Mandarin. Together, these findings support early noun dominance as a widespread phenomenon in the lexical acquisition debate but also provide evidence that language specificity also plays a minor role in children's early lexical development.

This research brings new evidence on early lexical acquisition in Wichi, an under-studied indigenous language in which verbs occupy a privileged position in the input and in conjunction with nouns are characterized by a complex and rich morphology. Focusing on infants ranging from one- to three-year-olds, we analyzed the parental report of infants’ vocabulary (Study 1) and naturalistic speech samples of children and their caregivers (Study 2). Results reveal that: (1) although verbs predominate in the linguistic input, children's lexicons favor nouns over verbs; (2) children's early noun-advantage decreases, coming into closer alignment with the patterns in the linguistic input at a MLU of 1.5; and (3) this early transition is temporally related to children's increasing productive command over the grammatical categories that characterize the morphology of both nouns and verbs. These findings emphasize the early effects of language-specific properties of the input, broadening the vantage point from which to view the lexical acquisition process.