Kids With Autism May Perceive Optical Illusions Differently From Most

What do you notice in the graphic above? Besides an eaten apple, chances are you can pick out two faces right away, too.

When analyzing an image or object, the brain combines it with personal experience and contextual information to “anticipate sensory inputs, address ambiguity, and fill in the missing information,” explains Emily Knight, assistant professor of Neuroscience and Pediatrics at the University of Rochester Medical Center. This reaction seems to differ for autistic children, however, as outlined in a study published in The Journal of Neuroscience.

Following up on previous research suggesting that the comprehension and feedback of visual stimuli are altered in children with autism spectrum disorder (ASD), Knight and her teammates showed Kanizsa illusions, otherwise known as illusory contours, to 60 children—including 29 diagnosed with the condition.

These optical illusions, named after Italian psychologist Gaetano Kanizsa, involve shapes with certain parts cut out. In their stead is negative space that prompts the brain to fill in the blanks and form a fuller image. The classic vase-and-face trick, similar to the apple drawing above, is one of them, though the category also includes geometric silhouettes, like the ones in the illustrations below.

While Pac-Man-like Kanizsa figures played in the background, the children, aged between seven and 17, were tasked to focus on a dot in the middle, as well as challenged to press a button when the speck turned from red to green.

The illusions were deliberately left in the peripherals, designed to be observed passively, so the participants wouldn’t actively “solve” them. Without having the children’s direct focus, the researchers were better able to assess the group’s response rates via their brainwave activity.

Electroencephalography (EEG) scans showed that participants diagnosed with ASD were slower at processing the illusory shapes. It’s worth reiterating that this test is about automatic responses, and that some children managed to figure out the implied objects—but their reactions were more delayed.

“This tells us that these children may not be able to do the same predicting and filling in of missing visual information as their peers,” details Knight. “We now need to understand how this may relate to the atypical visual sensory behaviors we see in some children on the autism spectrum.”

In a previous, similar study conducted last year, Knight and her colleagues observed how children with ASD dealt with body language. The participants were made to watch color-changing dots on a display, while images of a walking person were animated in the background. Neurodivergent children processed the body movements less frequently, indicating that they struggled more with social contexts.

Knight hopes to continue using optical illusions, and other mental stimuli, to better grasp “how people with autism see the world, so that we can find new ways to support children and adults on the autism spectrum.”

[via ScienceAlert and IFLScience, illustrations via Dreamstime]