Joint engagement and language development: Contributions of mother and infant

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Peter Mundy - Committee Chair


Theory and research support the facilitative effect of joint engagement, or time when a dyad is jointly focused on the same object or event, on language development. However, few studies have examined the trajectory of joint engagement over the course of the infant's development. Moreover, little is known about influences that contribute to individual differences in joint engagement, nor the degree to which dyadic patterns of behavior relate to language development beyond 24 months. The present study examined the development of joint engagement and its relationship to language in a sample of 91 mother-infant dyads observed longitudinally across the period of 9 to 24 months. At each age 7 minutes of caregiver free play were coded for joint engagement and caregiver scaffolding behaviors. Language was assessed at each time point with the MacArthur Communicative Development Inventory, and joint attention skills were assessed in an infant-tester paradigm at 9, 12, 15 and 18 months. Cognitive/language outcome was assessed at 36 months with the Reynell Developmental Language Scales. There were four major findings: (1) The developmental trajectory of joint engagement variables (i.e., total time in joint engagement and average duration of bouts) showed a stepwise pattern across the period of 9 to 24 months. (2) Maternal scaffolding during the second year was the most reliable predictor of average duration of bouts. (3) The MCDI and early measures of maternal scaffolding were the most reliable predictors of rate of change of joint engagement variables. (4) Both joint attention skills and the rate of change of time in joint engagement were uniquely related to 36-month cognitive/language outcome. Discussion focuses on the role both infant constraints and experiential factors play in optimal cognitive/language outcome.


Psychology, Social; Psychology, Developmental; Psychology, Cognitive

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