Adults with autism spectrum disorder (ASD) may be less surprised by unexpected changes than others around them, according to new research.

In a small study, researchers from University College London (UCL) conducted a simple learning task involving adults with and without autism. The results revealed that those who were the least surprised by unexpected images in the task had the most severe symptoms of the condition.

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“We know from previous studies that people with autism often aren’t surprised by things that would surprise other people,” lead author Dr. Rebecca Lawson said in a statement. “Our results suggest that this may be because of differences in how people with autism build expectations. Our expectations bias our behaviour in subtle ways, so being less susceptible to these effects may result in strengths as well as difficulties.”

Schematic of a single task, showing example stimuli Credit: Lawson, Mathys & Rees

Insisting on sameness or being inflexible to change a ritualized pattern, such as eating the same food every day, are diagnostic criteria for autism, according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is the standard manual for ASD diagnosis in the United States. But, there’s very limited research on how those with ASD react to environmental change, the study authors wrote in their paper published in Nature Neuroscience.

For their experiment, Lawson and her colleagues had 24 adults with autism and 25 adults without the condition complete a learning task involving various pictures (as seen in the image above) displayed on a computer after hearing a high or low sound.

The findings revealed that the ASD group tended to misjudge how changeable the environment was, which lessened how much their original expectations guided their response.

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“When we’re uncertain about our own beliefs, such as under volatile conditions, we’re driven more by our senses than our prior expectations,” Dr. Lawson said. If those with ASD are more often than not expecting rapid and unpredictable changes, it may explain their natural tendency to be overstimulated by the environment and be insensitive to circumstances or events that help direct perception and therefore influence response, she explained.

ASD causes people to have trouble communicating. The study found that those who had the most difficulty communicating corresponded with how accurately they were able to form expectations about upcoming photos in the experiment.

“The idea that differences in how people with autism build visual expectations may link to social difficulties is an intriguing possibility, and one that we would like to pursue further in consultation with members of the autism community,” senior author Geraint Rees said in a statement.

Understanding the various ways ASD affects individuals is important because symptoms vary greatly from one person to the next. Some of the common signs a child or adult has ASD include poor eye contact or a lack of facial expression, inability to start or hold a conversation, problems with coordination or odd moving patterns, and an unusual sensitivity to light, sound, or touch, according to Mayo Clinic.

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