Does Audiovisual Synchrony Predict Visual Fixation Patterns in 2-Year-Old Children with Autism?

Background: A recent study found that 2-year-olds with autism spectrum disorders (ASD) looked less at the eyes and more at the mouths of approaching adults, as compared with both typically-developing (TD) and with non-autistic, developmentally-delayed (DD) controls. A parallel study showed that toddlers with ASD failed to give preferential attention to point-light displays of human biological motion, again in contrast with both TD and DD controls. Instead, viewing by the ASD group was predicted by level of audiovisual synchrony (AVS): increased fixation was given to stimuli in which change in movement was accompanied by synchronous change in sound. In control children, viewing was unrelated to AVS. These results raised the hypothesis that, in toddlers with ASD, increased fixation on the mouth and decreased fixation on eyes may be due to increased attention to the synchrony of lip movements and speech sounds.

Objectives: The aim of this study is to determine whether the reduced visual fixation on eyes and increased fixation on mouths in toddlers with ASD is due to underlying preferential attention to physical rather than social contingencies.

Methods: Physical contingencies were identified by quantifying AVS in the eyes, mouth, body, and object regions of naturalistic, child-directed caregiver video stimuli, using techniques modified from the previous study. This approach was utilized to determine whether that for toddlers with ASD, but not for controls, visual fixation patterns to each region would be positively predicted by level of AVS, both spatially and temporally.

Results: Preliminary results suggest that, when viewing approaching caregivers, visual fixation in toddlers with ASD for a region appears to be correlated with the amount of AVS in that region. In concordance with previous reports, we found that the mouth was both the region with greatest AVS and the region attracting the greatest amount of visual fixation in the ASD group. We also observed that the timing of fixations is correlated with the change in baseline AVS for each region. In contrast, relative AVS does not appear to predict the visual fixation patterns of toddlers in either of the two control groups.

Conclusions: These results, along with the point light biological motion study, suggest that the preferential visual attention of toddlers with ASD is attracted by co-occurrences of change in motion and sound rather than by entreating social-communication signals. These findings, in turn, propose that children with autism may have atypical early experiences that would profoundly impact their development: seeing a face in terms of its physical contingencies but missing its critical social signals. These results may provide for new diagnostic tools and may also reveal an early stage in the development of compensatory and alternative strategies for interaction with others, particularly with respect to language and communication skills.