The Relationship between Pitch Contours in Infant-Directed Speech and Infant Risk for Autism
Objectives: The aim of this study was to characterise the utterances and pitch contours used by mothers when interacting with their infants at high-risk for autism compared to mothers of infants at low-risk for autism.
Methods: 18 mothers and their 12-month-old infants (12 male, 6 female) were participants in studies of early child development from three cohorts. Mother-infant dyads participated in a 15-minute recorded interaction. Infant risk for autism was assessed using the observer-rated Autism Detection in Early Childhood assessment (ADEC; Young, 2007) and the parent-report First Year Inventory (FYI; Reznick, Baranek, Reavis & Crais, 2007). Eight infants were assessed as at-risk for autism. A total of 5429 maternal pitch contours were extracted from the interactions and classified into contour types (rising, bell-shaped, sinusoidal, u-shaped, slowly-falling, rapid, flat and complex). Pearson product-moment correlations were performed to determine correlations between maternal pitch contour use and infant risk for autism.
Results: Mothers of clinically high-risk infants spoke less overall, with an average of 260.9 utterances during the interaction, compared to 334.2 spoken by mothers of low-risk infants. As infant risk on the parent-report FYI increased, mothers spoke fewer utterances (r=-.576, N=18, p=.01) and used fewer rising (r=-.586, N=18, p=.01), sinusoidal (r=-.636, N=18, p=.005), more complex (r=.584, N=18, p=.01) and more rapid (r=.526, N=18, p=.03) contours. As infant risk on the observer-rated ADEC increased, mothers spoke fewer utterances (r=-.631, N=18, p=.02), and used fewer flat shaped contours (r=-.679, N=18, p=.01) but more u-shaped contours (r=.619, N=18, p=.02).
Conclusions: These preliminary data suggest that mothers of high risk infants use different patterns of IDS than mothers of low risk infants. Further assessment of maternal IDS patterns from early infancy through the end of the first year of life in high and low risk infants is warranted to identify at what stage IDS patterns deviate between groups.