Vision, sound don’t sync for some kids with autism, study suggests

Watching a TV show where the words coming out of the actor’s mouth are not synched with his lips can be very distracting.

Researchers at Vanderbilt University, in a study published Tuesday in The Journal of Neuroscience, suggest this is something some children with autism experience all the time, because they cannot simultaneously process what their eyes are seeing and their ears are hearing.

People with an autism spectrum disorder can have significant communication difficulties and exhibit repetitive patterns of behavior and social challenges. The American Psychiatric Association, which publishes the bible of all diagnostic criteria of mental disorders, says people with autism spectrum disorder “have communication deficits, such as responding inappropriately in conversations” (among other symptoms). Their new DSM 5 criteria fold symptoms of the disorders into two broad categories: Impaired social communication and restricted or repetitive patterns and behaviors.

The study
Researchers wanted to know how well children with autism process what they hear and see. They studied 32 high-functioning children with autism and 32 typically developing children, who were similar in almost every way including IQ (with the exception of the autism). All were between the ages of 6 and 18.
The children sat in front of a video screen and were listening for and looking for simple stimuli like beeps and flashes and more complex stimuli, like a hammer hitting a nail or verbal cues. The study participants were asked to press buttons when the visual and audible stimuli were happening at the same time.

The results
Children with autism had a longer window of time within which they combined sights and sounds, says lead study author Mark Wallace, director of Vanderbilt’s University’s Brain Institute. It took about twice as long for them to connect the dots, compared to typically developing children.

“If you drop a pen in front of me, the visual and auditory signals are happening at the same approximate time,” explains Wallace. But in children with autism, it takes about twice as long for both of these signals to connect. “There’s a longer window of time within which they are binding sights and sounds.”

So one can imagine that if a typically developing child and a child with autism are listening to the same person speaking to them at the same time, they are not both getting the same message because the child with autism is taking longer to make the connections. That could contribute to language problems.

The study suggests that “impairments in low-level temporal sensory processing of audio and visual signals could play a role in speech perception in children with ASD.”

“If we think about language and social interactions, they are completely dependent on senses communicating,” says Wallace.

However, limited previous research has not been conclusive, says Marlene Behrmann, a professor of psychology at Carnegie Mellon University in Pittsburgh, who was not involved in the research. She says one earlier study suggests that visual and hearing signals sync up when children reach adolescence.


“This is a good article,” says Dr. Max Wiznitzer, a pediatric neurologist and autism expert at Rainbow Babies and Children’s Hospital in Cleveland, Ohio, who also was not involved in the research. But he suggests the study would reveal more if researchers had included a group of children with developmental language disorders, in addition to the typically developed children and those with autism. This would help researchers understand if the sensory problems are due to autism or a co-existing developmental language disorder.

Wiznitzer suggests that “a conservative interpretation of this study is, that the identified dysfunction can aggravate the core features of autism by having the potential to worsen communication ability.” He adds that a lot more research needs to be done to show if not being able to properly connect audio and visual cues just aggravates language problems in children with autism, or if this problem of processing multiple senses at the time is a “is a contributing factor to the core deficits of autism.”


Behrmann is excited about this research because she believes, if validated, it suggests the earlier in development children with autism receive therapy, the better they can sync up sights and sounds. That it might provide a “chance of off-setting some of the more complex behaviors later in life,” she says.

That’s one of the areas Wallace aims to explore. “Can we train these children to do better in binding sights and sounds? Can we (then) improve their language and social skills?” His ultimate goal is to improve the quality of life of children with autism.

What also needs to be studied, says Wiznitzer, is if interventions to retrain the brain to more quickly bridge the gap between what is heard and said will impact the autism in a positive way.

Dr. Michael Morrier, assistant director of the Emory Autism Center in Atlanta, suggests that contrary to popular belief that children with autism are “visual” learners, this study shows some children with autism are auditory learners, which in turn provides another clue as to how to help children with autism.

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