Speaking When Spoken To: Investigating the Impact of Parent-Child Conversations on Child Vocabulary Growth

What roles do caregivers play in children’s language development? Research studies initially addressed this question by examining the total amount of caregiver speech that children are exposed to. More recently, studies have focused on caregiver responses to children’s communication during their interactions, without considering caregiver initiations. Moreover, very little attention has been paid to the relation between caregivers’ communicative input initiating interactions with children and their input responding to children’s communication, particularly in relation to the roles the child plays––in other words, little attention has been paid to caregiver-child conversation.  In addition, studies of caregiver communicative input have primarily focused on caregivers’ verbal communication. This approach thus overlooks the role of caregiver gesture, which has been found to affect children’s later language outcome. My dissertation addresses the disconnect between the literatures on conversational function and caregiver gesture by investigating how these two dimensions jointly influence children’s language growth before kindergarten. Chapter 1 begins with a review of the literature on caregiver speech, responsiveness and gesture in relation to child language learning. Chapter 2 presents the study’s methods. Chapter 3 characterizes caregiver communicative input in terms of its conversational functions, focusing on speech and ignoring gesture. Chapter 4 characterizes the same data on caregiver communicative input taking gesture into account. Chapter 5 explores the impact of caregiver conversational input on child vocabulary development. The chapter is divided into four parts: (1) a description of the children’s vocabulary learning trajectory, the outcome variable to be predicted; (2) an analysis of the impact that caregiver conversational input has on child vocabulary growth when caregiver speech is analyzed without gesture; (3) an analysis of the impact that caregiver conversational input has on child vocabulary growth when caregiver speech is analyzed in relation to gesture; (4) a description of the characteristics of initiations that do and do not elicit responses. The study ultimately demonstrates that caregivers’ initiations and responses both play important roles in supporting child vocabulary development prior to school entry, as does parent gesture. Chapter 6 concludes with a discussion of the study’s findings, limitations, and implications for understanding how early caregiver-child interactions support language development.