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Early Vocabulary Acquisition: From Birth Order Effect to Child-to-Caregiver Ratio
Audun Rosslund1,2, Natalia Kartushina1, Nora Serres2,3
1Department of Linguistics and Scandinavian Studies, University of Oslo, Oslo, Norway.
Abstract:
Growing up with multiple siblings might negatively affect language development. This study examined the associations between birth order, sibling characteristics and parent-reported vocabulary size in 6163 Norwegian 8- to 36-month-old children (51.4% female). Results confirmed that birth order was negatively associated with vocabulary, yet exhibited a U-shaped pattern. A data-driven measure of "child-to-caregiver ratio" in the household was developed, in which old-enough siblings-females 1-3 years earlier than males-were considered caregivers for their younger siblings. This measure explained variance in vocabulary better than birth order, and indicates sex-differences in the age at which older siblings contribute to, rather than deplete, available resources. A child-to-caregiver ratio might better capture the interplay between language-learning resources and demands within households.
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