Atypical Tactile Expressions Using Japanese Ideophones in Adults With Autism Spectrum Disorders

Japanese ideophones (onomatopoeia) constitute a unique lexical system that conveys complex sensations and emotions through embodied sound symbolism. Because adults with autism spectrum disorder (ASD) show weak sensitivity to sound-symbolism, their engagement with ideophones may diverge from that of typically developing (TD) adults. We addressed this possibility in two experiments involving adults with ASD who have normal language abilities and no sensory-processing abnormalities.

In Study 1, thirty-one tactile ideophones were rated on five physical and two emotional dimensions using a semantic-differential questionnaire. In Study 2, participants palpated 15 fabrics and selected all ideophones that captured each sensation.

In Study 1, mean ratings, representational-similarity matrices, and response variabilities did not differ between groups, indicating that ASD adults share a semantic understanding of ideophones with TD adults. In Study 2, group-level choice distributions and the fabric representational-similarity structure based on those choices again aligned across ASD and TD groups. However, multidimensional scaling of individual choice profiles revealed pronounced dispersion in ASD. Two factors accounted for this variability: ASD participants selected fewer ideophones per fabric, and their ideophone combinations were highly idiosyncratic, whereas ideophone combinations were widely shared among TD individuals.

Taken together, the results show that adults with ASD possess intact semantic representations of tactile ideophones yet adopt a more restricted and individualized strategy when translating concrete sensory experiences into linguistic expressions. This localized, less convergent usage may contribute to the qualitative communication difficulties often observed in ASD, despite intact lexical-semantic knowledge and representational similarity structures.