Tactile Information Processing Mechanisms to Discriminate Foil Thickness

The purpose of this study was to measure tactile discrimination ability of foil thickness and propose sensory information processing mechanisms for such discrimination processes. In Experiment 1, difference thresholds for the thickness were measured using stainless foils. The difference thresholds were 5.9, 6.1, 6.4, 7.5, 9.0, and 10 μm for a foil thickness of 8, 10, 20, 30, 40, and 50 μm, respectively. In Experiment 2, subjective thickness between stainless and copper foils was compared. From the results of the experiments, it is concluded that the subjects discriminate foil thickness using material distortion information. Humans possess the ability to discriminate between the thickness of thin materials. John, Goodwin, and Darian-Smith (1989) measured tactile discrimination ability of thin metal plates (thickness of standard plates were 0.2 mm) and found that a difference in thickness of approximately 0.075 mm could be discriminated. They presented several hypotheses of strategies used by the subjects, and all strategies required for the subjects to sense the angles of finger joints to a precision of about 0.1 °. However humans can discriminate between thinner materials than the plates used in their study. The purpose of this study was to measure thickness discrimination ability for very thin materials and propose a hypothesis of information processing mechanisms for such discrimination.