Effect of touching manner and motion direction of human finger on human tactile recognition

The purpose of this paper is to investigate the effects of the touching manners and the motion directions of human finger in recognizing fine surface texture. The authors developed a measurement system to present a step-height of 10 to 1000 mum to the finger of the human subject to measure the human tactile sensation capability. The presentation device can control four parameters of the presentation, which are the step-height, the presentation velocity, the presentation angle, and the presentation temperature. Human subjects actively and passively touched and distinguished the step-heights to determine the different thresholds for step-heights. Also they passively touched and distinguished the step-heights with different motion directions of their fingers to determine the difference thresholds. As the results of the psychophysical experiments, it was found that the distinctive sensitivities of human tactile sensation in active-touch and passive-touch manners are different in discriminating between fine step-heights and that the directions of finger motion have little effect on the human tactile recognition of fine step-heights.