Study findings indicate that reduced orienting to synchronous sights and sounds within biological motion in infancy is an early sign of autism spectrum disorder.
"Currently, ASD cannot be reliably diagnosed before 2 to 3 years of age, and despite a lot of research we still know too little about the causes. Even if twin studies suggest that genetic factors play an important role, we still do not know enough about which specific genes are involved and how they affect the developing brain to cause ASD,” Terje Falck-Ytter, PhD, associate professor, department of psychology, Uppsala University, Sweden, said in a press release. “Our philosophy is that studying the early development of ASD will help clarify the picture.”
In a prospective, longitudinal study, researchers examined whether reduced visual attention to audiovisual synchrony in infancy could predict later ASD diagnosis among younger siblings of children with autism. The researchers used the same eye tracking task previously used in autistic children that examined how manipulations of audiovisual synchrony affected their viewing patterns while the infants watched point light displays of biological motion. In the eye tracking task, infants observed a computer screen where half displayed objects that moved in synchrony with a sound and the other half showed objects that moved without synchrony to sound. Then, researchers examined gaze data recorded at age 10 months and conducted diagnostic evaluation at age 3 years.
Forty-seven children participated in the current study. The results showed significant group differences (P = .013). Infants who later received ASD diagnosis did not pay attention to the audiovisual synchrony expressed within biological motion, demonstrated by their orienting equally long at both sides of the computer screen. However, both infants at low-risk (P = .022) and high-risk siblings without autism (P = .032) at age 3 years showed a strong preference for audiovisual synchrony.
“We expected an effect in this direction but were nevertheless surprised to see that the group differences were so large,” Falck-Ytter said in the release. “We believe the findings are important because they point to a rather basic function that has not been studied much earlier in this context."
The extent of difference in looking time remained significantly different between the three groups (P = .011). When comparing by sex, the researchers found that boys with later autism differentiated less between the conditions compared with boys in the high-risk group without autism (P = .025) and with low-risk boys (P = .004); although the direction of differences were the same for girls, they were not significant.
“Our findings suggest that infants with typical development, but not infants with later autism, orient to audiovisual synchrony within biological motion,” Falck-Ytter and colleagues wrote in Journal of Child Psychology and Psychiatry. “The findings, particularly if they generalize to multisensory processing more broadly, could have far-reaching consequences for our understanding of early developmental pathways in autism, and potential implications for early intervention.” – by Savannah Demko
Disclosures: Falck-Ytter reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.