HAPTIC IDENTIFICATION OF CURVED SURFACES

In two experiments, the active haptic identification of three-dimensio nal mathematically well-defined objects is investigated. The objects, quadric surfaces, are defined in terms of the shape index, a quantity describing the shape, and curvedness, a quantity describing overall cu rvature. Both shape index and curvedness are found to have a significa nt influence on haptic shape identification. Concave surfaces lead to a larger spread in responses than convex ones. Hyperbolic surfaces sho w a slight tendency to be identified with more difficulty than ellipti c ones. Surfaces with a high curvedness are identified more easily tha n those with a low curvedness. Results from experiments with constant and with random curvedness are indistinguishable. It is concluded that shape index and curvedness are psychophysically not confounded.