EFFECTS OF TASK-IRRELEVANT SOUNDS ON THE TACTILE PERCEPTION OF ROUGHNESS
Previous studies demonstrated that tactile sensations of surface roughness were affected by touch-produced sounds. We investigated whether task-irrelevant sounds differentially modified the tactile estimation of roughness and length. The results revealed that only white noise had a significant effect on the roughness estimations. Further, we investigated whether the same tendencies can be observed in the tactile roughness perception of smoother surfaces near the threshold level. The analyses of discrimination errors verified that the tactile roughness perception was modified by the auditory stimuli only in the coarser pair. In particular, white noise and pure tones affected the roughness in opposite ways: the white noise led to rougher sensations and the pure tones led to smoother sensations. The results suggest that task-irrelevant sounds modify the tactile roughness perception. However, it is indicated that the effects likely occur in a limited range of tactile surfaces or in the appropriate combinations between surface roughness and sounds.