Understanding Why Autistic People May Reject Social Touch

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One of the hardest challenges for families facing autism is the problem of touch. Often, autistic children resist hugging and other types of physical contact, causing distress all around.

Now, a new study offers insight into why some people shrug off physical touches and how families affected by autism may learn to share hugs without overwhelming an autistic child’s senses.

Yale neuroscientists recruited 19 young adults and imaged their brain activity as a researcher lightly brushed them on the forearm with a soft watercolor paintbrush. In some cases, the brushing was quick, and in others slow: prior studies have shown that most people like slow brushing and perceive it as affectionate contact, while the faster version is felt as less pleasant and more tickle-like.

None of the participants in the current study had autism, but the researchers evaluated them for autistic traits — things like a preference for sameness, order and systems, rather than social interaction. They found that participants with the highest levels of autistic traits had a lower response in key social brain regions — the superior temporal sulcus (STS) and orbitofrontal cortex (OFC) — to the slow brushing.

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According to Martha Kaiser, senior author of the study and associate director of the Child Neuroscience Laboratory at the Yale Child Study Center, the STS is a critical hub of the social brain. “This region is important for perceiving the people around us, for visual social stimuli and for perceiving social versus nonsocial sounds,” she says.

The current findings suggest that the region is also involved in processing social touch and that its response is linked to the individual’s social ability, she says.

The OFC, in contrast, helps the brain evaluate experiences — whether something is likely to be good or bad and if it involves pleasure or pain. “The brains of people high in autistic traits aren’t coding touch as socially relevant, that’s one interpretation,” says Kaiser of her findings. “The OFC is very important for coding reward so maybe they’re feeling the touch but in these individuals, their brains don’t code that type of touch as being as rewarding as in individuals with fewer autistic traits.”

If that’s the case, finding ways to make social experience — including touch — more rewarding might be one way to help autistic people connect better with others.

Indeed, Temple Grandin, the well-known author and animal scientist with autism, and the subject of a 2010 HBO biopic, famously built herself a “hug machine” to self-apply deep pressure to her body. She craved the feeling of being securely held, but also needed to be able to control the sensation herself, often finding touch from others too intense.

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A better understanding how social touch is processed differently by autistic and nonautistic people may lead to the development of strategies for family members and loved ones to touch people with autism in a way that soothes and fosters feelings of connection, rather than overwhelms.

Kaiser and her colleagues are already studying people with autistic spectrum disorders to explore these questions, particularly in children. Making social touch more rewarding early in development might further help autistic children learn social skills, since learning is heavily dependent on pleasure. And because later development relies on early experience, such a strategy could improve their overall development. “I think there are a lot of potential treatment applications for this work,” Kaiser says.

The study was published in Social Cognitive and Affective Neuroscience.

Maia Szalavitz is a health writer for TIME.com. Find her on Twitter at @maiasz. You can also continue the discussion on TIME Healthland‘s Facebook page and on Twitter at @TIMEHealthland.