The Hidden Dimension

On the forty-second page of “The Hidden Dimension” anthropologist Edward T. Hall wrote (emphasis added):

This classification can be broken down even further. The skin, for example, is the chief organ of touch and is also sensitive to heat gain and loss; both radiant and conducted heat are detected by the skin. Hence, strictly speaking, the skin is both an immediate and a distance receptor.

There is a general relationship between the evolutionary age of the receptor system and the amount and quality of information it conveys to the central nervous system. The tactile, or touch, systems are as old as life itself; indeed, the ability to respond to stimuli is one of the basic criteria of life. Sight was the last and most specialized sense to be developed in man. Vision became more important and olfaction less essential when man's ancestors left the ground and took to the trees, as I mentioned in the last chapter. Stereoscopic vision is essential in arboreal life. Without it, jumping from branch to branch becomes very precarious.

Visual and Auditory Space

The amount of information gathered by the eyes as contrasted with the ears has not been precisely calculated. Such a calculation not only involves a translation process, but scientists have been handicapped by lack of knowledge of what to count. A general notion, however, of the relative complexities of the two systems can be obtained by comparing the size of the nerves connecting the eyes and the ears to the centers of the brain. Since the optic nerve contains roughly eighteen times as many neurons as the cochlear nerve, we assume it transmits at least that much more information. Actually, in normally alert subjects, it is probable that the eyes may be as much as a thousand times as effective as the ears in sweeping up information.

The area that the unaided ear can effectively cover in the course of daily living is quite limited. Up to twenty feet the ear is very efficient. At about one hundred feet, one-way vocal communication is possible, at somewhat slower rate than at conversational distances, while two-way conversation is very considerably altered. Beyond this distance, the auditory cues with which man works begin to break down rapidly.

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(Anchor Books, May 1975. Paperback, 240 pages. ISBN: 0385084765; EAN: 9780385084765.)