Autism - Image credit SCA Svenska - creative commonsImagine watching a video in which the speaker’s voice does not seem to match her mouth movements. How much harder is it to understand the speaker? For people with autism spectrum disorders (ASD), reconciling out-of-phase sound and visual stimuli, like in a lagging video, is an ongoing challenge. Research from Vanderbilt University’s Vanderbilt Brain Institute have found that children with ASD have trouble integrating simultaneous input from the eyes and the ears. These findings could help in developing more effective treatments for people with autism.

The researchers assessed 32 high-functioning children with autism ages six to 18 and 32 typically developing children demographically matched with the children with ASD. The children completed various tasks designed to evaluate their responses to stimuli. Most of the tasks were computer-generated and involved stimuli like flashes and beeps, a hammer hitting a nail, or speech. The children had to determine whether the audio and visual elements happened simultaneously.

According to the results, children with ASD have enlargement in the temporal binding window (TBW), which means that their brains have difficulties correctly matching the visual and auditory events that happen in a period of time. Furthermore, the children with ASD exhibited problems in how strongly they associated audiovisual speech stimuli.

These findings may offer an explanation as to why children with ASD so often put their hands over their ears—they could be trying to limit the types of incoming stimuli. It is possible that these findings may also have applications for disabilities like dyslexia and schizophrenia, since sensory functioning is often disrupted for people with those disorders.

“Children with autism have difficulty processing simultaneous input from audio and visual channels … It is like they are watching a foreign movie that was badly dubbed, the auditory and visual signals do not match in their brains,” explained Mark Wallace, Ph.D., director of Vanderbilt Brain Institute, who led the study.

This research is published in The Journal of Neuroscience.

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