A new study published in the journal Autism research has provided fascinating insights into how people with autism spectrum disorder (ASD) experience touch. Researchers have found that people with ASD have lower physiological responses to touch than typically developing individuals, but they report higher ratings of pleasant and unpleasant tactile sensations. This discrepancy highlights a complex relationship between subjective experience and physiological response in individuals with ASD.
Touch plays a crucial role in human communication and social interactions, helping to establish and maintain relationships even before the development of verbal skills. This form of communication is particularly important because it can convey emotional and social meanings, promoting attachment, social affiliation, and bonding. The pleasurable effects of certain types of touch, called affective touch, are usually associated with gentle caresses that activate a specialized sensory system in the skin.
However, for people with ASD, sensory experiences can be significantly different. Individuals with ASD often exhibit atypical sensory processing, which can significantly impact their social interactions and quality of life. Previous research has shown that these people may find certain types of touch unpleasant or overwhelming, contributing to their social challenges. The new study aimed to deepen our understanding of how affectionate touch is perceived and processed in adults with ASD, given the limited amount of research available on this topic.
“The interest of our laboratory lies in the neurobiology of complex social behaviors. The ultimate goal of our research is to provide new fundamental neuroscientific insights to better illuminate the mechanisms underlying social dysfunctions,” said study author Olga Dal Monte, associate professor of psychology at the University of Turin. .
“Affective touch plays an essential role in the maintenance of interpersonal relationships, conveying emotional and social meanings that can shape neurodevelopmental trajectories. Therefore, difficulties processing tactile input or the experience of abnormal tactile sensitivity may hinder social behaviors, having a significant impact on individuals’ relational lives.
“This challenge is particularly pronounced in ASD, characterized by both sensory disturbances and social impairments. Despite the central role of this phenomenon among the symptoms of ASD, there are few studies exploring the effects of this specific form of social exchange on behavior and the autonomic nervous system.
The study involved 48 participants: 24 people with ASD and 24 typically developing controls. Participants with ASD were recruited from the Piedmont Adult Autism Center in Turin, Italy, and were diagnosed according to established criteria. The control group consisted of typically developing individuals with an identical age and gender distribution.
Participants sat comfortably with their left arm resting on a table, hidden from view by a wooden panel. Each participant received a series of tactile stimuli on the dorsal side of their left forearm. These stimuli included emotional touchwhich involved slow, gentle movements, and a touch control, characterized by a tapping sound. The experimenter delivered the tactile stimuli and recorded the participants’ physiological responses using a device measuring skin conductance, a common indicator of autonomic nervous system activity.
After each touch, participants rated the touch based on its affective (pleasant) and unpleasant components using a numerical scale. The experience was designed to be flexible, allowing participants to take a break if they felt tired or overwhelmed.
Researchers found that people with ASD had lower overall skin conductance levels than typically developing participants, indicating a weaker autonomic response.
Although typically developing participants showed a higher physiological response to affectionate touch than to control touch, this differentiation was not observed in the ASD group. In other words, people with ASD did not show a distinct autonomic response to affective touch compared to controlling touch.
Despite the lack of physiological differentiation, individuals with ASD rated the affective and unpleasant aspects of touch higher than typically developing participants. This suggests that they subjectively perceive touch more intensely on both positive and negative scales.
“Analyzing the complexity of the affective tactile experience of ASD using both subjective and physiological measures allowed us to highlight possible divergences compared to the neurotypical population but also, and much more interestingly, , to observe and highlight the gaps between the conscious experience of the subjects and the more conscious experience of the subjects. implicit that resides in bodily responses,” Dal Monte told PsyPost.
“A deeper understanding of the aspects that characterize autistic people in emotional situations is crucial for a better understanding of the distinctive challenges associated with this syndrome and may have implications for diagnosis and therapeutic approaches.”
Limitations of the study include an exclusive focus on adults with ASD who meet specific support criteria, limiting generalizability to those with varying levels of functioning; an unbalanced distribution between the sexes, in favor of men; and a focus on young adults, who may not represent the experiences of older people.
Future research could include a more diverse range of individuals on the autism spectrum, encompassing different levels of functioning and balanced gender representation. Studies should also explore sensory processing in older adults with ASD to understand age-related changes. Incorporating additional physiological measures such as heart rate and pupil dilation could provide a more complete understanding of autonomic responses.
The study, “Autonomic and hedonic response to affective touch in autism spectrum disorder,” was authored by Francesca Capiotto, Giulia Romano Cappi, Ilaria Mirlisenna, Alessandro Mazza, Giovanni Cicinelli, Chiara Lauritano, Roberto Keller and Olga Dal Monte.