Haptic Exploration and the Perception of Texture Orientations

The perceptual sensitivity of touch to orientation differences in adjacent segments of textures with different configurations was measured in two experiments. We found that sensitivity to the orientation difference was not only a function of the magnitude of that difference but of the reference orientation. In Experiment 1, we examined the exploratory patterns that were used to make these judgments and found that distinct exploratory patterns were used early but tended to converge on one dominant pattern. In Experiment 2, constraining exploration trajectories to previously unobserved patterns and halving exploration time only slightly lowered perceptual accuracy but did not alter the pattern of effects. That the configuration of the texture elements influenced accuracy more than did the exploratory procedure used has implications for how texture is encoded through the skin and the procedural knowledge underlying haptic texture exploration.