Kinaesthetic and cutaneous contributions to the perception of compressibility

Abstract

Compressibility or hardness of objects is an important aspect in haptic perception. Both cutaneous and kinaesthetic information are used for the perception of compressibility. In this paper, the relative role of these contributions is investigated. This is done with psychophysical experiments using a purpose-made silicon rubber stimulus set. The fabrication and characterisation of the stimuli are described, as well as discrimination experiments with and without surface deformation of the stimuli. With the cutaneous cues of surface deformation present, the Weber fraction for hardness discrimination was 0.12. When surface deformation was removed and only kinaesthetic cues were available, the Weber fraction doubled, suggesting that the cutaneous sense contributes almost three quarters to hardness perception, and the kinaesthetic just over one quarter, if the information is integrated in a statistically optimal fashion.