Effects of sounds on tactile roughness depend on the congruency between modalities

Recent studies have demonstrated that the tactile roughness perception of surface texture was modified when touch-produced sounds or non-touch-produced sounds were presented while exploring a surface. Our previous research demonstrated that white noise modified tactile roughness perception of an abrasive paper with a certain particle size. In the present study, we investigated whether the dependence of the effects of sound on the particle size of surfaces indicates the correspondences of perceived roughness between tactile and auditory information. The results revealed that the congruency of roughness information between the modalities is necessary to modify the effects of sounds on tactile roughness perception with regard to not only the intensity of the crossmodal effects but also whether the direction of the auditory effects on tactile roughness perception is smoother or rougher.