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 42months were examined in relation to children's vocabulary skill on a standardized measure 1year later (e.g., 30, 42, and 54months). 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.
© 2012 The Authors. Child Development © 2012 Society for Research in Child Development, Inc.