# Comparison of gesture-vocal synchrony and gestures of two children aged 3 to 26 months with and without autism spectrum disorder

## TL;DR

This study compares how babies with and without autism use gestures and coordinate them with speech during interactions with their mothers from 3 to 26 months.

## Contribution

The study provides new insights into gesture-vocal synchrony differences in early language development between children with and without autism.

## Key findings

- Babies with autism showed less gesture-vocal synchrony and lower-quality interactions with their mothers.
- The child without autism demonstrated better coordination and more varied gestures, supporting later language development.
- Despite similar gesture types, the frequency and synchrony between the babies and their mothers differed significantly.

## Abstract

The objective was to compare gesture-vocal synchrony in language functioning between mothers and babies and the gestural typology of babies from 3 to 26 months of age, one of them with autism spectrum disorder (case R), diagnosed at age 3, and the other without diagnosis (case B). It was select moments in which there was greater mother-baby interaction, from a bank of mother-baby interactions footage, from 3 to 26 months. It was analyzed using the Eudico Linguistic Annotator software ( ELAN), considering multimodal categories of sign language and speech of mothers and babies for descriptive statistical analysis. The results showed differences in the frequencies and types of gestures between the babies and also in the synchrony between them and their mothers. In the case of B., the gesture-vocal synchrony and variety of gestures is inserted in a context of conjunction between him and his mother in the first year of life, which gave rise to the second enunciative mechanism in the second year of life. In case R, the conjunction relationships were not established, as the difficulties in reading discomfort and annoyance gestures, very present in the baby since its first months of life, hindered the engagement and shared attention of the mother and her baby, disfavoring the inscription of gesture as language. R. showed language acquisition delay at 26 months. Although the gestural typology of B and R are similar, the frequencies, the quality and, above all, the gesture-vocal synchrony differ between dyads.

O objetivo foi comparar a sincronia gesto-vocal no funcionamento de linguagem entre mães e bebês e a tipologia gestual de bebês dos 3 aos 26 meses, sendo um deles com transtorno do espectro do autismo (caso R), diagnosticado aos três anos, e outro sem diagnóstico (caso B). A partir de um banco de filmagens das interações da mãe e do bebê realizadas dos 3 aos 26 meses, foram selecionados momentos em que houve maior interação entre mãe e bebê. Foram analisados por meio do software Eudico Linguistic Annotator (ELAN), considerando categorias multimodais de linguagem gestual e de fala das mães e dos bebês para análise estatística descritiva. Os resultados evidenciaram diferenças nas frequências e tipos gestuais entre os bebês e também na sincronia entre eles e suas mães. No caso de B. a sincronia gesto-vocal e variedade de gestos está em um contexto de conjunção entre ele e sua mãe no primeiro ano de vida, o que fez emergir o segundo mecanismo enunciativo no segundo ano de vida. No caso R, as relações de conjunção não se estabeleceram, pois as dificuldades na leitura de gestos de desconforto e incômodo pela mãe, muito presentes no bebê desde seus primeiros meses de vida, dificultaram o engajamento e a atenção compartilhada da mãe e seu bebê, desfavorecendo a inscrição do gesto como linguagem. R. apresentou atraso na aquisição da linguagem aos 26 meses. Apesar da tipologia gestual de B e R serem similares, as frequências, a qualidade e, sobretudo, a sincronia gesto-vocal diferem entre as díades.