Integrating multimodal information about surface texture via a probe: relative contributions of haptic and touch-produced sound sources

We experimentally assessed the relative contributions of tactile and auditory information to multisensory (i.e., bimodal) judgments of surface roughness using a rigid probe. Participants judged the magnitude of surface roughness and their corresponding confidence in three modality conditions: touch-only, audition-only (i.e., touch-produced sounds only) and touch+audition. The results indicated that touch cues were weighted 62% and auditory cues 38% in the bimodal judgments. Participants also proved to be more confident of their judgments in the bimodal condition. Implications for the creation of virtual roughness presented through uni- vs. multimodal interfaces is also addressed.