"Thomas A. Easton - Let There Be Light" - читать интересную книгу автора (Easton Thomas A)

 Even the Russians, though they approach the problem a little differently, think in terms of using the
skin. At last report, they had a woman who could read with her naked fingertips, even through a sheet of
glass. How she did it, they didn't know, but they were studying her and her odd talent with an eye toward
training others to do the same. So far as I know, they have met with no great success.
The system I wish to discuss here is the one being developed and investigated by Professor Paul
Bachy-Rita and his colleagues at the Smith-Kettlewell Institute of Visual Science in San Francisco.*
(*Dr. Bach-y-Rita's recent book, "Brain Mechanisms in Sensory Substitution," Academic Press, New
York, 1972, is the source of much material in this article and I acknowledge his work gratefully.)
Their tactile vision substitution system (TVSS) uses an ordinary television camera to drive, through
appropriate circuitry, an array of either vibrators or electrical stimulators which, because of the small size
of the electric pulses they deliver and their high frequency (60 pulses per second), feel like vibrators. The
circuitry reduces the TV image to a dot picture, rather like a black and white mosaic, in which each dot
controls one stimulator in the array (e.g., light-on, dark-off). The array, applied to an area of skin,
actually permits a blind person to "see." Not color, and not yet very well, but well enough to read large
letters on a wall, to locate a telephone or coffee cup, and to discover that a wife or husband doesn't
really look as nice as the blind subject had thought.



Figure 1. The first tactile vision substitution system consisted of (from right to left) a modified
dentist's chair with an array of mechanical stimulators (vibrators) mounted in the back, a
television camera which reduced its picture to a square array of points, each point of which
corresponded to one vibrator, and a slanted display board It weighed 400 pounds and was thus
not portable, but it did show that such a sensory substitution system is feasible.

The original version of the TVSS, built in the late 1960's, used a standard television camera and had
an array of mechanical stimulators mounted in the back of a modified dentist's chair, as shown in Figure
1. Thus, when the subject sat down in the chair and leaned back, the vibrators were in position to
impress their "image" upon his skin. The system was not portable; it weighed 400 pounds and was quite
bulky; but the movements of the camera could be controlled by the subject.
Later models, however, were made portable, the first such consisting of a stimulator array on the
belly and a, one-pound camera slung over one shoulder like a handbag, and connected by fiber optics to
a "look-out" station be side the eye. The latest differs from this principally in that the TV camera weighs
only six grams and is mounted on a glasses frame, thus permitting a blind person to attain, in some
respects, nearly normal vision. The stimulus array delivers small electrical pulses to the skin and, since the
electrodes are much smaller than the vibrators, it is much lighter than the earliest mechanical arrays.
The exact nature of the apparatus involved, though, is not as important as the nature of the
phenomena observed and the "visual" results obtained. The first TVSS, heavy, bulky, and with only an 8
x 8 array of stimulators, proved that the approach was workable, that blind persons could use senses
other than their ears and hands to obtain intelligible information about the world around them. Later
models showed just how much like vision the tactile substitution can be.
Most of the subjects who have cooperated in the development and study of the TVSS have been the
so-called early blind, that is, people who have been blind from or nearly from birth. (Visually-guided
behavior does not develop in man until about two months after birth, so it is not possible to diagnose
blindness before then.) These persons have had no prior experience of vision, but with some training on
the TVSS, all became "visually" sophisticated enough to be susceptible to the visual illusions.
In fact, one such person was using the set-up of Figure 1 (the slanted board is used to allow the
demonstration and use of certain distance cues, such as the height of an object on the board) when the
board unexpectedly fell forward onto the camera. Several days later, the experimenter recreated the
incident by operating the camera's zoom lever without warning the subject. The subject threw up his arms