Summary: Researchers report that people with autism spectrum disorder (ASD) may have difficulty distinguishing which tactile sensations belong to their own actions and which belong to others.
Source: Ghent University.
The sense of touch may play a more crucial role in autism spectrum disorder (ASD) than previously assumed
The doctoral research of Eliane Deschrijver, published with colleagues, indicates that adults with ASD may struggle to determine whether a tactile sensation originates from their own action or from someone else’s. These findings point to a potentially important connection between sensory processing of touch and everyday social difficulties experienced by people on the autism spectrum.
ASD: social challenges and sensory sensitivities
Sensory processing differences are common in ASD. Some people become overwhelmed in busy or noisy environments, others are less sensitive to pain, and many report discomfort or dislike when being touched. Large-scale studies have previously shown that touch sensitivity correlates more closely with the severity of daily social difficulties in ASD than do visual or auditory sensitivities.
To explore why touch in particular is so closely linked to social challenges, Deschrijver and colleagues examined how the brain uses an individual’s own sense of touch to interpret observed touch in others. The working idea is that the brain constantly compares expected sensations from one’s own actions with actual incoming sensory signals. If a tactile sensation matches what one expects from one’s own movement, the brain attributes it to oneself. If it does not match expectations, the brain can attribute the sensation to another person’s action, supporting the distinction between self and other.
“We think that the human brain uses the sense of touch to help distinguish self from others,” explains Dr. Marcel Brass. “When I make a movement that should produce a touch, I expect a corresponding sensation. If the incoming touch does not align with that expectation, the brain can treat the touch as coming from someone else. This mechanism helps in understanding other people’s actions.”
Neuroscientific research using EEG
Deschrijver’s team used electroencephalography (EEG) to compare brain responses to touch in adults with and without ASD. Participants observed a human or a wooden hand touch a surface while receiving a brief tap-like tactile stimulus to their own finger. The tactile stimulus either matched or mismatched the expected consequence of the observed action. This “action-based somatosensory congruency” paradigm reveals how the brain signals when observed touch does not correspond to one’s own touch.
In adults without ASD, the brain rapidly signaled when a tactile sensation did not match the expected self-generated touch. This quick neural detection supports the brain’s ability to label observed touch as belonging to another agent rather than to oneself.
By contrast, adults with ASD showed a reduced neural response when the external touch did not correspond to their own expected touch. In other words, their brains were less likely to signal that observed touch belonged to someone else. Importantly, participants who reported stronger sensory difficulties also exhibited larger disruptions in this neural signaling. Those same individuals tended to report more severe social problems in daily life.
Eliane Deschrijver notes that this is the first evidence linking the neural processing of tactile information to everyday social difficulties in adults with ASD. The results suggest a novel theoretical bridge between sensory and social impairments in the autism spectrum.
Professor Jan R. Wiersema adds that while these findings improve understanding of ASD and related sensory and social challenges, it is too soon to draw firm conclusions about clinical applications. If future studies replicate these results in other groups, including younger children, this mechanism could become a target for interventions aimed at improving social functioning.
The study was carried out at the EXPLORA research centre at Ghent University, led by Dr. Roeljan Wiersema and Dr. Marcel Brass, who also supervised the PhD work. The research used EEG measures and an action-based somatosensory congruency paradigm to probe how observed and felt touch are distinguished in the brain.
Source: Ghent University
Image source: Illustrative image provided by NeuroscienceNews.com.
Original research: “Action-based touch observation in adults with high functioning autism: Can compromised self-other distinction abilities link social and sensory everyday problems?” by Eliane Deschrijver, Jan R. Wiersema and Marcel Brass. Published in Social Cognitive & Affective Neuroscience, online September 9, 2016. doi:10.1093/scan/nsw126
Abstract (summary of the study)
The study examined whether adults with high-functioning autism show altered neural signaling when a tactile consequence of an observed action does not match their own touch expectations. Using an action-based somatosensory congruency paradigm, participants observed a human or wooden hand touching a surface while receiving a tactile tap that either matched or mismatched the observed movement. The ASD group displayed a diminished congruency effect for human hands in the P3-complex, indicating a reduced ability to signal observed action-based touch that does not match their own touch experience. This neural reduction correlated with self-reported social and sensory everyday difficulties in the ASD group. The findings propose a theoretical link between sensory processing differences and social impairments in autism.
Feel free to share this summary of the research while preserving citation of the original study and its authors.