Enhancing effect of tangential vibration on human vibrotactile sensitivity

Vibrotactile sensitivity is usually defined by the minimum amplitude when subjects perceive the vibration with a frequency which generates to the perpendicular direction on the skin surface. In this paper, we are interested in how the vibrotactile sensitivity with a frequency is changed under the condition adding the tangential vibration with the other frequency which generates to the tangential direction on the skin surface. Through all of experiments, we found that the vibrotactile sensitivity at the frequency of 8, 10, and 25 Hz is enhanced approximately 30 % with the p-value of below 0.1 %.