Two-finger Stiffness Discrimination with the Stochastic Resonance Effect

We investigated the ability of two fingers to discriminate stiffness with stochastic resonance. It is known that the haptic perception at the fingertip improves when vibrotactile noise propagates to the fingertip, which is a phenomenon called the stochastic resonance. The improvement in the haptic sensation of a fingertip depends on the intensity of the noise propagating to the fingertip. An improvement in the haptic sensation of multiple fingertips does not require multiple noise sources, such as vibrators, to be attached to multiple fingertips; i.e., even a single vibrator can propagate noise to multiple fingers. In this study, we focus on stiffness discrimination as a task using multiple fingers, in which the thumb and index finger are used to touch an object and perceive its stiffness. Subsequently, we demonstrate that the stiffness perception is improved by propagating sufficiently intense noise to the thumb and index finger using only a single vibrator. The findings indicate the possibility of improving the haptic sensation at multiple fingertips using one vibrator.