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A Longitudinal Investigation of the Role of Quantity and Quality of Child-Directed Speech in Vocabulary Development


  • This research was supported by grants from the National Institute of Child Health and Human Development: K99/R00HD055522 to the author, and P01HD40605 to Susan Goldin-Meadow. I thank the participating families for sharing their child’s language development with us; Anthony Dick, Susan Goldin-Meadow, Janellen Huttenlocher, Daniel Kreisman, and Barbara Alexander Pan for comments on earlier versions of the article; Karyn Brasky, Laura Chang, Elaine Croft, Kristin Duboc, Jennifer Griffin, Sarah Gripshover, Kelsey Harden, Lauren King, Max Masich, Carrie Meanwell, Erica Mellum, Molly Nikolas, Jana Oberholtzer, Lilia Rissman, Becky Seibel, Meredith Simone, Calla Trofatter, Kevin Uttich, Julie Wallman, and Kristin Walters for help in collecting and transcribing the data; Christine Bascetta for coding; and Kristi Schonwald and Jason Voigt for administrative and technical assistance.

concerning this article should be addressed to Meredith Rowe, Department of Human Development, 3304T Benjamin Building, University of Maryland, College Park, MD 20742. Electronic mail may be sent to


Quantity and quality of caregiver input was examined longitudinally in a sample of 50 parent–child dyads to determine which aspects of input contribute most to children’s vocabulary skill across early development. Measures of input gleaned from parent–child interactions at child ages 18, 30, and 42 months were examined in relation to children’s vocabulary skill on a standardized measure 1 year later (e.g., 30, 42, and 54 months). Results show that controlling for socioeconomic status, input quantity, and children’s previous vocabulary skill; using a diverse and sophisticated vocabulary with toddlers; and using decontextualized language (e.g., narrative) with preschoolers explains additional variation in later vocabulary ability. The differential effects of various aspects of the communicative environment at several points in early vocabulary development are discussed.