Post written by Dr. Lei Xuan and Dr. Christine Dollaghan based on an article in Journal of Child Language

Our research addressed questions about the kinds of words that appear in the early vocabularies of bilingual children.  Evidence from some languages, including English, has shown that young children acquire words for people and things before words that label actions and attributes or words that have grammatical functions. However, the hypothesis of a universal preference for nouns (i.e., a “noun bias”) in early lexical development has been challenged by studies suggesting that children acquiring languages such as Korean and Mandarin Chinese may show a weaker preference for nouns.

We used a unique research design to examine the extent of noun bias in 50 bilingual toddlers who were simultaneously acquiring English and Mandarin, two strikingly different languages that are believed to fall near the extremes of the noun bias continuum.  By studying noun bias within each child’s English and Mandarin vocabularies we hoped to minimize the threat of confounding due to individual differences in cognitive and sociodemographic factors that could affect the noun preference.  By focusing on children whose parent-reported vocabularies in both English and Mandarin fell between 50 and 300 words we hoped to control for variations in noun bias at different vocabulary sizes.  By recruiting 50 children, we ensured that statistical power was adequate for our analyses. Our objective was to provide the clearest test to date of the hypothesis that the degree of noun bias differs in these two languages.  Specifically, we hypothesized that the mean percentage of nouns in English would exceed the mean percentage of nouns in Mandarin by at least 15%, a value selected based on a synthesis of evidence from monolingual children in five languages.

Our results showed a mean difference in the percentage of English and Mandarin nouns of 16%, providing evidence that the preference for nouns was greater in these children’s English than in their Mandarin vocabularies.  Although nouns predominated the total number of words and the 50 most frequently produced words in both languages, the most frequent 50 words in these children’s English vocabularies included substantially more nouns and substantially fewer verbs than did the most frequent words in their Mandarin vocabularies.

The findings converge with previous findings from monolingual children and suggest that not only universal cognitive and perceptual factors but also cross-linguistic variations in language input should be considered in understanding the composition of early vocabularies. The within-subject bilingual design is likely to be a fruitful approach to understanding the influences on children’s lexical development.

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