Masataka Sawayama^1,2 (), Takashi Itahashi³, Yoshinori Dobashi^1,2, Haruhisa Ohta³; ¹Graduate School of Information Science and Technology, Hokkaido University, Japan, ²Prometech CG Research, Japan, ³Medical Institute of Developmental Disabilities Research, Showa Medical University, Japan

Individuals with autism spectrum disorder (ASD) differ from typically developing (TD) individuals not only in social interaction and communication but also in atypical sensory responses, such as hypo-responsiveness to pain or hypersensitivity to sensory signals. These sensory characteristics suggest that the visual appearance in daily environments may differ substantially between ASD and TD individuals. However, previous studies on sensory and perceptual processing have focused mainly on early visual processing, such as contrast sensitivity or color discrimination. To clarify the characteristics of perceptual experience in ASD under more natural environments, the present study focused on material perception and compared optical material discrimination between ASD and TD individuals. Using physically based computer graphics rendering, we generated object images in which six optical material dimensions were systematically manipulated: gloss contrast, gloss distinctness-of-image, translucency, metallicity, transmittance, and highlight inconsistency (cf. Sawayama et al., 2022). Discrimination sensitivity for each dimension was measured in ASD and TD groups using an odd-one-out task. Results showed that at the group level, no significant differences were observed between ASD and TD participants for any of the material dimensions. We further analyzed representational dissimilarity matrices (RDMs) across the six tasks within each group. In the TD group, the gloss contrast dimension showed relatively high similarity with the metallicity task but low similarity with the translucency-related task. In contrast, the ASD group showed weaker similarity between the gloss contrast and metallicity tasks, but stronger similarity between the gloss and translucency tasks compared to the TD group. These findings suggest that although the overall ability to discriminate material properties does not differ substantially between ASD and TD individuals, the underlying material representations that support discrimination vary considerably between the groups. This indicates that ASD individuals may structure and relate material attributes in a perceptual space distinct from that of TD individuals.