15715
Vocal Coordination during Early Parent-Infant Interactions Predicts Language Outcome in High Risk Infants
Like adults, typically developing infants and their mothers adjust the timing of their vocal behavior to coordinate with their conversational partner. This type of coordination begins as early as 4 months of age and is related to developmental outcomes (Beebe et al., 1988; Jaffe et al., 2001).
Due to strong genetic etiology, infant siblings of individuals with autism spectrum disorder (ASD) are at high risk (HR) for being diagnosed not only with ASD, but also with significant language delays (Zwaigenbaum et al., 2005). Studies comparing HR infants to infants without an older sibling with ASD (low risk infants, LR), have revealed early differences in social communication, allocation of attention, and synchrony with an interactive partner (Paul et al., 2011; Droucker et al., 2013; Yirmiya et al., 2006), all of which have implications for vocal coordination.
Objectives:
The aim of this study is to examine the vocal characteristics of mother-infant interactions in a HR sample in order to better understand the development of infants at risk for autism as well as the common occurrence of language delays in this population.
Methods:
Participants include 35 nine-month-old infants (25 HR; 10 Low Risk: LR) videotaped at home during a 5-minute unstructured toy play interaction with their mothers. All mother and infant vocalizations and periods of silence were coded on a moment-by-moment basis, generating the following variables: frequency of vocalizations, average duration and variability of latency to respond (the time between when one person stops speaking and the partner’s response), average duration of intrapersonal pause (the time between two vocalizations of the same speaker), and frequency of interruptions (when one speaker speaks during a partner’s vocalization).
All HR infants were followed longitudinally to 36 months, and two standardized measures of language (Macarthur Bates Communication Development Inventory and Mullen Scales of Early Learning) were administered at 18, 24, and 36 months. We used these measures to classify infants as language delayed (LD) and to create a continuous measure of language ability in toddlerhood.
Results:
HR mothers had more variable latencies to respond than LR mothers (p=0.026). Mothers and infants in LD dyads were more likely to interrupt each other than mothers and infants in ND dyads (p’s<0.05). LD mothers and infants were also less correlated with one another (r = -.02,n.s.) in average duration of latency to respond than ND dyads (r =0.81,p<.001), and the degree of similarity between mothers and infants on this variable predicted a continuous measure of language development in toddlerhood (p<.001). A binary logistic regression predicting Outcome (LD vs. ND) with frequency of infant and mother interruptions and coordination of latency to respond correctly classified 85% of the infants as LD or ND (Χ2=14.63, p=0.002).
Conclusions:
Results indicate that differences in the ability to coordinate vocalizations with those of a partner in an interaction are predictive of later language outcome. Findings will be discussed in terms of early markers of language delay and the potential cascading effects of early delays on development.