Many children grow up hearing multiple languages, learning words in each. How does the number of languages being learned affect multilinguals’ vocabulary development? In a pre-registered study, we compared productive vocabularies of bilingual (n = 170) and trilingual (n = 20) toddlers aged 17–33 months growing up in a bilingual community where both French and English are spoken. We hypothesized that because trilinguals have reduced input in French and English due to time spent hearing their third language, they would have smaller French–English vocabulary sizes than bilinguals. Trilinguals produced on average 2/3 of the number of words in these languages that bilinguals did: however, this difference was not statistically robust due to large levels of variability. Follow-up analyses did, however, indicate a relationship between input quantity and vocabulary size. Our results indicate that similar factors contribute to vocabulary development across toddlers regardless of the number of languages being acquired.

中文翻译：

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多语言幼儿两种语言的词汇发展：双语者和三语者的比较


许多孩子在成长过程中都会听到多种语言，并学习每种语言的单词。学习的语言数量如何影响多语言者的词汇发展？在一项预先注册的研究中，我们比较了在法语和英语双语社区长大的 17-33 个月双语 (n = 170) 和三语 (n = 20) 幼儿的生产性词汇。我们假设，由于三语者由于花在听第三语言上的时间而减少了法语和英语的输入，因此他们的法语-英语词汇量会比双语者小。三语者平均产生的单词数量是双语者的 2/3：然而，由于存在较大的变异性，这种差异在统计上并不明显。然而，后续分析确实表明了输入数量和词汇量之间的关系。我们的结果表明，无论学习多少种语言，类似的因素都会促进幼儿的词汇发展。