ABSTRACT
Issues of blindness, plasticity, and spatial function have a long history in philosophy, physiology, and psychology. It is not clear where to begin in trying to introduce the topic. Rather arbitrarily, I begin with the renaissance philosophers. A major idea, pointing out similarities between touch and vision, can be traced at least as far back as Descartes’ Dioptrics in 1635. He argued that distance was perceptible by means of a natural geometry based on angles of the wrists holding two rods. The angles of the wrists and the distances between the two hands gave a basis for estimating the distance of intersection of the rods. Similarly, binocular vision can support distance perception of a fixated object by registering the angles of convergence of the two eyes along with the interocular distance.
