Influence of Roughness on Contact Force Estimation During Active Touch

Haptic sensations consist of cutaneous information elicited on the skin and kinesthetic information collected by the musculoskeletal system; there is a bidirectional relationship between haptic sensations and exploratory movements. Previous researches have investigated exploratory movement strategies for active haptic perception and the influence of exploratory movements on haptic sensations. This paper investigates the influence of roughness on the estimation of contact force during the active touch of samples with different textures. Two stimuli with different roughness were prepared and the contact force was measured when the participants rubbed pairs of samples with identical and different stimuli under the instruction of keeping the contact force constant. Eleven healthy adults participated in the experiment. The results showed that the accuracy of controlling the contact force for identical samples was not significantly different between coarse and smooth textures, whereas the contact forces between the coarse and the smooth sample when rubbing pairs of them were significantly different for six of eleven participants. These participants overestimated the contact force exerted for the coarse stimulus in comparison with the smooth stimulus. Thus, the results imply that textures during rubbing can yield perceptual bias for the contact force exerted; however, there are individual differences for this effect. There might be a complex perception mechanism for kinesthetic information involving cutaneous information.