Reduced preference for smooth over rough surfaces in autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social communication deficits, repetitive behaviors and restricted interests. Studies have reported atypical sensory responses in individuals with ASD. While atypical affective responses to being touched by others have been documented, preferences for the physical properties of objects in ASD remain poorly understood. Here, we conducted psychophysical experiments to examine whether individuals with ASD show atypical affective responses to object surfaces varying in smoothness. Forty adults with ASD and 40 typically developed (TD) adults provided magnitude estimates of pleasantness or perceived smoothness while their right fingers or forearm were stimulated with raised-dot surfaces of varying interdot spacing. Magnitude estimates of both perceived pleasantness and perceived smoothness decreased with increasing interdot spacing. The decrease in pleasantness was consistently less steep in the ASD group than in the TD group for both forearm and fingers. In contrast, evidence for group differences in smoothness was limited and insufficient to support a reliable group difference. These findings indicate that, compared with TD adults, adults with ASD may show a reduced preference for smoother over rougher surfaces, highlighting an atypical response to textured surfaces, especially with respect to pleasantness.