What New Research Revels about Autism, Stimming, and Touch

Monday, April 14, 2025

Tapping a pen, shaking a leg, twirling hair—we have all been in a classroom, meeting, or a public place where we find ourselves or someone else engaging in repetitive behavior—a type of self-stimulatory movement also known as stimming. For people with autism, stimming can include movements like flicking fingers or rocking back and forth. These actions are believed to be used to deal with overwhelming sensory environments, regulate emotions, or express joy, but stimming is not well understood. And while the behaviors are mostly harmless and, in some instances, beneficial, stimming can also escalate and cause serious injuries. However, it is a difficult behavior to study, especially when the behaviors involve self-harm.

“The more we learn about how benign active tactile sensations like stimming are processed, the closer we will be to understanding self-injurious behavior,” said Emily Isenstein, PhD (’24), Medical Scientist Training Program trainee at the University of Rochester School of Medicine and Dentistry, and first author of the study in NeuroImage that provides new clues into how people with autism process touch. “By better understanding how the brain processes different types of touch, we hope to someday work toward more healthy outlets of expression to avoid self-injury.”

Researchers used several technological methods to create a more realistic sensory experience for active touch—reaching and touching—and passive touch—being touched. A virtual reality headset simulated visual movement, while a vibrating finger clip—or vibrotactile disc—replicated touch. Using EEG, researchers measured the brain responses of 30 neurotypical adults and 29 adults with autism as they participated in active and passive touch tasks. To measure active touch, participants reached out to touch a virtual hand, giving them control over when they would feel the vibrations. To measure passive touch, a virtual hand reached out to touch them. The participant felt vibrations when the two hands “touched," simulating physical contact. As expected, the researchers found that the neurotypical group had a smaller response in a brain signal to active touch when compared to passive touch, evidence that the brain does not use as many resources when it controls touch and knows what to expect.

However, the group with autism showed little variation in brain response to the two types of touch. Both were more in line with the neurotypical group's brain response to passive touch, suggesting that in autism, the brain may have trouble distinguishing between active and passive inputs. “This could be a clue that people with autism may have difficulty predicting the consequences of their actions, which could be what leads to repetitive behavior or stimming,” said Isenstein.

It was a surprising finding, particularly in adults. John Foxe, PhD, director of the Golisano Intellectual and Developmental Disabilities Institute at the University of Rochester and co-senior author of the study, remarked that this may indicate the difference in children with autism could be greater than their neurotypical counterparts. “Many adults with autism have learned how to interact effectively with their environment, so the fact that we’re still finding differences in brain processing for active touch leads me to think this response may be more severe in kids, and that’s what we also need to understand.”