Phrasing and fragmented time in “pathological” mother-infant vocal interaction

Abstract

This paper presents the results of an ecological perturbation study of mother-infant vocal interaction. We compared the temporal organisation of spontaneous interactions between 3–month-old infants and mothers who suffered from “borderline personality disorder” and control mothers and infants. Previous studies of vocal interaction have shown that they present a hierarchical temporal organisation. This study focused specifically on “phrasal” units in the flow of expressive sounds produced by mothers and infants that can be segmented according to rules similar to those used by music performers, composers and listeners. Phrases in interaction are perceived and shaped by features such as final lengthening, pausing or lowered pitch and intensity. Acoustic analyses of audio recordings of 34 mother-infant dyads were performed. Results showed that the interactions of mothers with “borderline personality disorder” contained fewer “phrases” with longer phrase final pauses than those of control dyads. These findings suggest that the temporal organisation and quality of vocalisation, rather than the degree of maternal involvement, has a fundamental effect on the infant's motivation to partake in lively interaction.