Observations on active touch.

TLDR: Preliminary results indicate that the cross-modal matching of these novel preceptions is possible even for a naive observer, and that practice can bring about errorless judgments in all observers so far tested.

Abstract: ed by solid geometry (slant, curvature, edge, corner) did not seem any more complex to introspection than the solely visible features of things abstracted by plane geometry (triangle, square, circle). A new set of shapes has now been devised for the study of object-perception by active touch. They consist of ten solid sculptures, or free-forms, made of plastic, the surfaces being curved, with no planes, edges, or corners. They are intended to be felt with two hands (and are called "feelies"). Approximately one-half of each surface (the "rear") is convex; the other half (the "front") consists of six convexities with intermediate saddles or concavities. In general, there are five protuberances around a central protuberance, but no object is symmetrical, either radially or bilaterally. They cannot, therefore, be distinguished from one another by counting. Each is readily discriminated from every other by vision of the "front" surface. They are also mutually distinguishable by feeling, although with some error and hesitation for an unpracticed observer. Replicas of the ten objects are available, made from the same molds. It is therefore possible to present one object to the hands and the same or a different object to the eyes simultaneously. Preliminary results indicate that the cross-modal matching of these novel preceptions is possible even for a naive observer, and that practice can bring about errorless judgments in all observers so far tested. Passivity and activity in touch and vision. In passive touch the individual makes no voluntary movements. Similarly, in passive vision he makes no eye movements, which means that he must voluntarily fixate his eyes on a point specified by the experimenter. Neither state is natural to an individual. In a tactual situation, the observer will explore with his fingers unless prevented and, in a visual situation, he will explore the focussable light, fixating, accommodating, converging and pursuing. Both senses are normally active. The passive stimulation of the skin or the retina is necessary for the study of the receptorcells in the skin or the retina, but the experiences resulting are atypical. In active touching and looking the observer reports experiences of a quite different order. They correspond to