9309371 TURVEY This research will address how perception of the properties of objects and surfaces can be achieved on the basis of touch and without benefit of vision. The focus will be on the dynamic touch system, in which perception is tied to circumstances that affect the muscle and tendon states (as when effort is expended in order to heft an object or strike surrounding surfaces with a cane). In these experiments, people will wield an unseen object to perceive its length, weight, shape, or orientation, use a cane to explore occluded objects, apertures, and surfaces at a distance, or oscillate a taut strand anchored at both ends to perceive objects attached to the strand. They will adjust movable surfaces or visible pointers to quantify the perceived properties. Distance, length, orientation, and so on, will be manipulated. The experiments will be directed, first, at identifying the capabilities of the dynamic touch system, i.e., what properties can be perceived reliably, and, second, at the basis of that perception. The latter will highlight the physical constants that relate the lawfully varying forces and motions; these constants are assumed to govern perception of object and surface properties by dynamic touch. Identifying hand-related capabilities and the physical properties that underwrite them will have implications for the design of robotic limbs and prostheses, as well as for the general theory of special purpose cognitive mechanisms. ***
