Analyzing the effect of sibling number on input and output in the first 18 months

Catherine Laing, Elika Bergelson

Research output: Contribution to journalArticlepeer-review


Prior research suggests that across a wide range of cognitive, educational, and health-based measures, first-born children outperform their later-born peers. Expanding on this literature using naturalistic home-recorded data and parental vocabulary reports, we find that early language outcomes vary by number of siblings in a sample of 43 English-learning U.S. children from mid-to-high socioeconomic status homes. More specifically, we find that children in our sample with two or more—but not one—older siblings had smaller productive vocabularies at 18 months, and heard less input from caregivers across several measures than their peers with less than two siblings. We discuss implications regarding what infants experience and learn across a range of family sizes in infancy
Original languageEnglish
Number of pages21
Early online date6 Jan 2024
Publication statusE-pub ahead of print - 6 Jan 2024

Bibliographical note

© 2024 The Authors

Cite this