Babysibs Dyadic prosody Jean Quigley School of Psychology

Babysibs: Dyadic prosody Jean Quigley School of Psychology This work was financially supported by a grant from the Irish Research Council for the Humanities & Social Sciences (IRCHSS).

Prosody & ASD Prosodic atypicalities (e. g. , of rhythm, stress, intonation) one of most common & earliest clinical features of ASD Also found in prelinguistic vocalisations & cries of infants-at-risk-of. ASD Interaction partners’ prosody may also be affected

Prosody & Infant Directed Speech IDS: simplified speech register & acoustic modification Prosodic or pitch manipulation in IDS • relies on infant interest in & attention to speech signal • shapes infant vocalisations

Social feedback interactive loop • Mothers selectively respond to/imitate speech-related infant vocalisations; Infants use this contingent feedback to shape their babbling • Both quality & quantity of IDS decline in situations of reduced synchrony and as a function of infant responsiveness

Typical trajectory of prosodic modification in IDS • Pitch range of maternal IDS narrows & utterance intensity decreases with infant age • Similar patterns evident in infant vocalisations Maternal response to: • development of infant vocal & imitative ability? • infants’ waning interest in the characteristic acoustic features of IDS?

Research Questions: 1) Do at-risk dyads follow typical developmental patterns of prosodic expression in interaction over time? i. e. , do infants and mothers display decreased pitch range & corresponding decrease in utterance intensity? 2) Is the matching process intact in at-risk dyads? i. e. , are maternal & infant pitch range & utterance intensity changing in synchrony with each other?

Babysibs Pilot Study Prospective longitudinal video microanalysis design Dyads filmed every 4 weeks in naturalistic face-to-face interaction (3– 12 m; 18 m). 10 infants (7 m/3 f, no known developmental risk factors) 9 infants (4 m/5 f, at genetic risk, 1+ sibling(s) ASD) All non-vegetative vocalisations produced by mother & infant at age 12 & 18 months sampled. Acoustic measurements accomplished using PRAAT vocal analysis software

1) Trajectory of Prosodic Development: 12 -18 m Pitch Range 640 At-risk infant Pitch range (Hz) 620 Low-risk infant 600 At-risk mother 580 Low-risk mother 560 • ↓ for both low-risk & at-risk groups of mothers & infants • higher for at-risk infants & mothers at both 12 & 18 m 540 520 500 Infant age (months)

Intensity 72 Intensity (d. B) At-risk infant 70 • ↓ for low-risk group Low-risk infant 68 Low-risk mother 66 At-risk mother 64 62 • ↑ for at-risk group exaggerated intensity typical of IDS more evident over time in both mother & infant at-risk vocalisations 60 Infant age (months)

2) Prosodic matching within dyads • In low-risk dyads, pitch range & intensity associated for mother & infant at 12, but not at 18 months • fits with decreasing interest in & reliance on synchrony in TD after 1 st year – mother responds also with less synchrony. • In at-risk dyads, no matching at 12 months or at 18 months.

Disrupted reciprocal vocal imitation? Restricted infant ability • to imitate maternal prosody may mean narrowing of prosodic expression not initiated by mother • to perceive matching in maternal prosody may reduce its stimulatory effect & affect preference for IDS may partly account for different developmental trajectory pof at-risk dyads. Early patterns of interactional prosody can be predictive of later outcomes & could be used as a non-invasive marker for ASD (see Fusaroli 2016 meta-analysis).

Collaborators: Sarah Lawson, Sinéad Mc. Nally Thanks especially to the families and to all the students who have worked on the project. Also to the funding body, Irish Research Council.