Developmental changes in audio-visual speech integration during the first year of life in infants at elevated and typical likelihood of autism.

Researchers studied how babies at higher and typical risk for autism learn to watch faces during speech in their first year. Most babies naturally shift from looking at eyes to looking at mouths as they develop. However, babies at higher autism risk showed delayed patterns in this shift. Those later showing autism signs had even flatter development patterns. These early differences in how babies process speech might be early signs that could affect communication development.

This longitudinal eye-tracking study examined audiovisual integration development in infants at elevated likelihood (EL) and typical likelihood (TL) of autism across 6, 9, and 12 months. Using the McGurk effect paradigm, researchers tracked infants' visual attention patterns to facial features during speech processing. Results showed typical developmental progression from eye-looking at 6 months to mouth-looking at 9-12 months across both groups. However, EL infants demonstrated delayed developmental shifts in attention patterns.

Infants showing autism signs at 24 months displayed flatter developmental trajectories in eye-to-mouth preference shifts. The study suggests early audiovisual processing differences may serve as subtle developmental markers with implications for later communication development.

Findings suggest audiovisual integration patterns may serve as early developmental markers. Delayed attention shifts to mouth region in elevated likelihood infants could inform early screening approaches and highlight importance of monitoring sensory processing development for communication outcomes.

Sample size not reported, limiting interpretation of statistical power. Study methodology details unclear from abstract. Exploratory nature of 24-month outcome analyses limits definitive conclusions about predictive validity.

Infants' ability to integrate auditory and visual information, i.e., audiovisual integration (AVI), emerges during the first year and is crucial for effective communication and early development. However, there is limited longitudinal research on how AVI develops across the first year of life, particularly in infants at elevated likelihood of autism (EL). This study aimed to investigate the developmental trajectories of AVI in response to congruent and incongruent speech stimuli in EL and typical likelihood (TL) infants at 6, 9, and 12 months. Using eye-tracking techniques and the McGurk effect paradigm, we explored infants' preferential looking behavior towards facial features (eyes vs. mouth) and their response to audiovisual congruence.

EL infants were then evaluated at 24 months to explore the associations between AVI and later autism-related traits. Across likelihood groups, infants showed a robust developmental shift from greater attention to the eyes at 6 months toward increased attention to the mouth at 9 and 12 months, consistent with expected developmental changes in audiovisual speech processing. Infants also displayed higher mouth preference in the non-fusible mismatch condition at 6 months, suggesting early sensitivity to audiovisual incongruence. Interestingly, EL infants showed a delayed developmental shift toward mouth-looking across the first year of life.

Exploratory outcome analyses revealed that infants showing clinical signs of autism at 24 months displayed a flatter developmental trajectory in eyes-to-mouth preference. The present study emphasizes the importance of examining sensory processing trajectories in EL infants, as delayed shifts in attention to the mouth could signal subtle developmental differences that may have long-term implications for subsequent communication skills.