Vibrotactile Stimuli Applied to Finger Pads as Biases for Perceived Inertial and Viscous Loads

The perception of the mass and viscosity of an object is based on the dynamic forces applied to our hands when we jiggle or lift the object [1], [2], [3]. This force is commonly assumed to be sensed by kinetic receptors [4] in our muscles or tendons. When jiggling objects, we also experience the cutaneous deformation of our finger pads. In this study, we show that the dynamic vibration on the finger pad influences our perception of mass and viscosity. We experimentally confirm that the vibration on the finger pad, that synchronizes with the hand´s accelerations or velocities, enhances the perceived changes in the mass or viscosity when the vibrotactile stimuli and the changes in the mass and viscosity are in the same perceptual direction. For example, when the increased mass and an acceleration-synchronized tactile stimulus-which is a positive bias for the mass-are simultaneously presented to the experiment participants, they respond that the perceived increase in the mass is enhanced. In contrast, when the tactile and proprioceptive stimuli are in perceptually opposite directions, the vibrotactile stimuli cancel the perceived changes in the mass and viscosity. In particular, the effect of the velocity-synchronized vibration on perception is stronger than the effect of the actual viscosity.