A Multidimensional Scaling Analysis of Texture Gradient Perception via Haptic Exploration

More than one line of research has established roughness as the primary subjective attribute of textured surfaces explored by touch and to be a robust attribute largely unaffected by exploratory velocities or whether exploration is active or passive in nature. Roughness perception appears to be based on sensitivity to spatial distributions of texture elements. We investigated sensitivity to these spatial properties by using texture gradients of known form, explored by one or two fingers, and subjected to multidimensional scaling analysis. Our data suggest that irrespective finger use, perceivers are sensitive to direction and magnitudes of gradients, but not in strict conformance with these physical dimensions, and that a third (but unknown) dimension may also be involved