Toward Optimizing Man's Tactile Communication

Abstract

Man is tactually literate! This has been known for some time-for at least as long as the blind have been known to read with their finger tips scanning Braille symbols. Helen Adams Keller not only reads with her fingers and writes wich them through a typewriter, but also she listens with the skin of her hands and speaks with her fingers in a semiprivate system of encoding and decoding the kinds of informarion ordinarily called or literate, Man's integument can be substituted in linguistic matters for his ears, his eyes, or for both. Geldard (1957) has referred to rhe work of both Gaulc (1936) and Katz (1930, pp. 90-104) who thirty years ago investigated the feasibility of circurnventing deafness by applying sounds directly to the surface of the skin through stimulus-producing electromechanical transducers. Their results, and those of more recent investigations (Wiener, et al., 1949-195 1 ) , suggest that this is not feasible. In spite of the many similarities between hearing and skin sensations-and there are many as Bekesy (1959) has shown-such attempts appear futile in the light of our present knowledge. It does not appear possible to make any simple direct transcriptions of speech-patterned sound energy that when applied to the skin result in meaningful percepts of patterns. The limiting features of the skin seem to be the slowness wich which its nerves react relative to the auditory nerves, and the nonindependence of stimulus frequency and intensity in the cutaneous sense (Anderson & Munson, 1951; Bekesy, 1959; Geldard, 1957). A caution is necessary, however, that this conclusion not be overgeneralized. There is at least one datum to indicate that sounds may be directly perceived through the skin, albeit the sensory transcriptions may nor be simple and direct. Whether complex or simple, cutaneous transcriptions of such speechpatterned sound energies apparently are perceived and interpreted directly as speech in at least one instance! Specifically, Helen Keller is able to interpret that she hears through whatever stimuli act on three fingers--one placed on the throat just over che larynx, one placed just in front of the lips, and the third placed just beside the nose of the speaker. The resulting cutaneous sensations are ap'This paper is based on a presentation made by the author during an invitational research symposium on cutaneous sensitivity held at the US Army Medical Research Laboratory, Fort Knox, Ky., February, 1960. 'The author expresses his appreciation to the Emory University Research Committee for providing funds in support of this publication.