Similarities And Differences Among The Senses

Abstract

Each sense department appears specialized to process certain types of information. Yet the senses display similarities of function as well. Some of these similarities are superficial but others are deeper; they appear at four levels: (1) phenomenology; (2) information processing; (3) psychophysics; (4) neurophysiology. Similarities (and differences) at these levels may bear on sensory substitution in neural prosthetic devices (for instance, on tactile systems that could provide speech and spatial lay-out information to the deaf and blind). Examples of similarities appear in: (1) synesthetic resemblances between the attributes of pitch (hearing) and brightness (vision); (2) the identification of shapes by sight and by touch; (3) the skin as a model for the retina and for the cochlea. However, these similarities provide limited direct application to sensory aids. Several tactile systems (e.g., Braille, Optacon, Tadoma) do not rely on modes of functioning simply translated from one modality to another. It may be better to focus on the differences rather than on the similarities among the senses, and to gear sensory aids to the substitution modality's particular strengths.