Sibling Concordance for Viewing Social Dynamic Scenes in Children with ASD and Typical Development

Background: Very recent findings in monozygotic and dizygotic twins toddlers show a concordance in the viewing of social scenes. This concordance is observed for levels of preferential attention and for time spent in the social stimuli (Constantino et al, 2017). Results of this study point to a high concordance in monozygotic twins, a lower concordance in dizygotic and non-concordance for non-siblings in the time spent looking at eyes or mouth, suggesting a strong genetic component influencing this type of behaviour.

Objectives: The objective of the present study was to measure such concordance in a non-twin but brotherhood sample using a paradigm of visual preference displaying at the same time biological and geometric motion.

Methods:

Twenty-eight siblings from 13 brotherhoods participated in the study: 4 brotherhoods of children with autism spectrum disorders (ASD) of which 1 brotherhood contain 3 siblings (so a total of 9 children with ASD) and 9 brotherhoods of typically developed (TD) children of which 1 brotherhood contain 3 siblings (so a total of 19 TD children) and thirty non-sibling children. Age characteristics are as follows: in the brotherhood group (mean=11.9, sd=5.7, range=2.7-25 years) and in the non- sibling group (mean= 9.9, sd = 3.2, range = 4.7- 17.4 years). ASD diagnosis was based on DSM IV-R and ADI-R criteria. Tobii T120 eye-tracker was used to measure looking behavior in a preferential viewing paradigm. Participants were presented with a movie consisting of dynamic geometric images (DGI) and dynamic social images (DSI) displayed simultaneously on the screen and percentage of time spent looking at DGI and DSI was measured for all participants.

Results: We found a significant positive correlation between the percentage of time spent looking at DSI in paired sibling (r =0.72; p=0.002), regardless of the diagnosis. This correlation was not observed among the singleton children, randomly paired.

Conclusions: These results highlight that visual engagement to biological motion could be viewed as a neurodevelopmental endophenotype of variation in social information gathering strategies, not only for autism but also for the typically developing population.