Social Timing refers to temporal synchronising in social interactions, which plays a vital role in the developmental dynamics of parent-infant interactions. Autism Spectrum Disorder (ASD) is a neurodevelopmental condition marked by apparent difficulties in temporal synchrony, that extend across modalities and impact interactions, as well as postulated diminished joint and shared attention, affecting social engagement and coordination. The current thesis investigates shared attention and temporal synchrony in naturalistic interactions using a novel micro-coding methodology: the Synchrony of Communication in Autism: Evaluation by Micro-Analysis (SCAEMA). SCAEMA evaluates Matching Synchrony (through gaze synchrony), Sequential Synchrony (of vocal response latency), and Bidirectional Synchrony (a time series through cross-correlation analysis).
The first empirical chapter (Chapter 3) applies SCAEMA in typically developing (TD) infants, considering both age-related changes and the impact of Mutual Shared Attention (MSA). The second empirical chapter (Chapter 4) investigates MSA and temporal synchrony through SCAEMA in non-verbal ASD-diagnosed and non-ASD children, controlling for Developmental Delay/Learning Disability (DD/LD). The third empirical chapter (Chapter 5) introduces Musical Interaction Therapy (MIT), an early parent-mediated intervention that uses live music to scaffold the timing of the interaction, alongside redirecting parental synchrony. This chapter investigates the impact of MIT on MSA and temporal synchrony assessed through SCAEMA.
Overall, the results from the thesis revealed that Matching Synchrony of gaze in TD infants experienced an age-related decline at 10 months and was influenced by MSA, with higher percentages of gaze synchrony observed during shared attention episodes. Bidirectional Synchrony was present across all ages, emphasizing its early emergence in infant communication. ASD children exhibited significantly less Matching Synchrony of gaze, MSA and Bidirectional Synchrony compared to non-ASD children, irrespective DD/LD status. While statistically significant improvements in Matching Synchrony of gaze and MSA were observed after six months of MIT, challenges arose in attributing these changes solely to therapeutic interventions due to the absence of control groups and baselines. Sequential Synchrony, or vocal response latency did not correlate with chronological age nor MSA, possibly suggesting nuanced developmental trajectories. Additionally, non-verbal ASD children’s vocal response latencies showed no significant differences from those with no ASD diagnosis, irrelevant of their DD/LD statuses. Six months of MIT did not appear to impact vocal response latencies nor Bidirectional Synchrony. This thesis introduces valuable insights into interpersonal synchrony in TD and ASD making valuable contribution to the field of temporal synchrony.