Children with autism see simple movement twice as quickly as other children their age, and this hypersensitivity to motion may provide clues to a fundamental cause of the developmental disorder, according to a new study.
Such heightened sensory perception in autism may help explain why some people with the disorder are painfully sensitive to noise and bright lights. It also may be linked to some of the complex social and behavioral deficits associated with autism, says Duje Tadin, one of the lead authors on the study and an assistant professor of brain and cognitive sciences at the University of Rochester.
"We think of autism as a social disorder because children with this condition often struggle with social interactions, but what we sometimes neglect is that almost everything we know about the world comes from our senses. Abnormalities in how a person sees or hears can have a profound effect on social communication," says Tadin.
Although previous studies have found that people with autism possess enhanced visual abilities with static images, this is the first research to discover a keener awareness of motion, the authors write. The findings were reported in the Journal of Neuroscience on May 8 by Tadin, co-lead author Jennifer Foss-Feig, a postdoctoral fellow at the Child Study Center at Yale University, and colleagues at Vanderbilt University.
In the study, 20 children with autism and 26 typically developing children, ages 8 to 17, looked at brief video clips of moving black and white bars and simply indicated which direction the bars were heading, right or left.
Each time a participant made the correct direction choice, the next video clip became slightly shorter and thus a little more difficult. When they made a mistake, the next video became a bit longer and thus easier to see. In this way, the researchers were able to measure how quickly children with autism can perceive motion.
The researchers found that when the bars in the image were just barely visible, both groups of children performed identically. When the contrast or darkness of the bars was increased all participants in the study got better at perceiving the direction of movement. "But kids with autism, got much, much better-performing twice as well as their peers," says Foss-Feig. In fact, the worst performing participant with autism was roughly equal to the average of the participants without autism.
"This dramatically enhanced ability to perceive motion is a hint that the brains of individuals with autism keep responding more and more as intensity increases. Although this could be considered advantageous, in most circumstances if the neural response doesn't stop at the right level it could lead to sensory overload," explains Foss-Feig.