Over and over again it has been shown that neither the congenitally blind nor those whose vision has become defective have any better sense of touch than the average person. With an esthesiometer, their power to recognize the distance between the points of a calipers is shown to be no better than that of an ordinarily sensitive individual. This is illustrated in other ways. Certain blind persons, even those born blind, are known to be able to distinguish colors more or less accurately, that is, at least the three primary colors. Their power to do this is consequent upon a faculty of recognizing differences in heat absorption. The ordinary seeing person going into a room in the dark recognizes at once the difference between a pencil and a piece of metal of the same shape and size by its weight and the greater tendency of the metal to feel colder. When we are not sure whether a pillar in a structure is of stone or an imitation, we determine this by touch, and the fact that stone absorbs heat rapidly while wood and other imitations of stone do not. It is the same faculty for distinguishing specific heat that enables certain blind people to recognize colors. If pieces of cloth of different colors are put over snow when the sun is shining on them, it will be found that black absorbs much more heat than the colored cloths, or white, and consequently that the snow melts faster beneath the black. After black comes red, then green, then blue. It is this difference in the power to absorb heat that the blind recognize and thus distinguish colors after long patient training of themselves.
Obstacle Sense.—An example of the value of training is the so-called obstacle sense which has been rather carefully studied in recent years. By means of it blind people are able to avoid larger obstacles and to know when they are passing an open door or window on a corridor or a building alongside a street. Blind children have been known to play in a garden where there were trees and other obstacles and carefully avoid them even while moving rather rapidly. This sense is disturbed whenever there is loud noise in the vicinity. It is not very active and yet it is of considerable value to the blind. Its disturbance by noise would seem to indicate that it is due to some sense faculty in the tympanum, or ear drum. It exists in everybody, but remains quite undeveloped except in those who need it and therefore learn to make use of it.
Touch and Sight.—The triumph of training is to be seen in the cases of those who are born blind and deaf and who yet are taught to understand through lip and throat reading by the tips of the fingers and taught to talk by being shown patiently the method by which others accomplish it, though the only avenue to their brain is the dull sense of touch which means so little for the ordinary individual. The cases of Laura Bridgeman and of Helen Keller illustrate how a sense that is usually quite neglected can be made to supply the place of both the eyes and the ears by patient, persistent training. Lip reading by sight is, of course, a very interesting example of the same principle that can be learned by anyone who has good sight in a comparatively short time. There are compensations of this kind and powers of development latent in every sense and function of the body that can be [{215}] employed to make life interesting and to restore usefulness after nearly every form of lesion or defect. Practically all of this compensatory power is mental, hence its place in psychotherapy. We do not increase the power of the sense but by concentration of attention the mind is rendered capable of obtaining definite information from sensory stimuli that are present in every person but that are ordinarily neglected.
Hearing.—One of the most surprising instances of the value of training for cases in which favorable results seemed quite out of the question, is Urbantschitsch's method of training the deaf to hear. After investigating it personally I reported it in the International Clinics. [Footnote 24] Patients who could hear but very little, indeed, only the loudest noises, were trained by means of loud shouting and the hearing of loud notes gradually to catch sounds more and more easily until not infrequently they could hear rather well. Sometimes even those who were thought to be absolutely deaf to sound were found to be able to hear very loud sounds and then it was invariably discovered that by practice they could be made to hear much more. The secret of the success consisted not in any increase in the power to hear, but entirely in training the attention to recognize and differentiate sounds so that what seemed at first a confused murmur gradually became intelligible. It is exactly the same process as that by which a man learns to read with his fingers. He is not able to differentiate the letters but after a time it is possible to do so without difficulty.
[Footnote 24: Lippincott & Co., Phila., Vol. IV, 8th series, 1899.]
Equilibrium.—There are typical examples of almost as striking increase of muscle sensation, or rather of ability to distinguish minute differences in muscular sensation, noted in those who train this faculty carefully. Acrobats succeed in developing wonderful control over muscles and marvelous response to slight disturbance of equilibrium. The ordinary individual has comparatively small balancing powers, but the slack-rope performer seems almost to defy the laws of gravity, because he has learned so to coordinate all muscular action as to enable him to maintain his balance. He has trained himself to distinguish every variety of message from his semicircular canals. Of itself neither of these senses gives us very much information, indeed, only as much as we ask for from it, but when we pay careful attention to the minute details of the information that it imparts, we are able to use it to great advantage.
Muscle Training.—It is this power of training to enable us to appreciate minute sensations that forms the basis of the Frenkel treatment of tabes. For the proper guidance of the muscles the muscular sense is all-important, though ordinarily we are quite unconscious of the information it conveys. This is seriously disturbed by the degeneration in tabes. The patient can, however, be taught to use even the slight amount of it that remains to great advantage or else to avail himself of some other compensatory sensations which will enable him to guide his muscles in various motions much better than before.
This same faculty can probably be employed in many other conditions. Frenkel has shown that it is applicable in paralysis agitans and markedly relieves the rigidity that is so annoying a symptom. It gives these patients something to occupy their minds, too, which means a great deal for their [{216}] general condition, for occupation of attention saves them from neurotic disturbance of themselves.
Sufferers from infantile paralysis can be taught to do many things with their weakened muscles that seem to be quite impossible to them. It requires patience to get results, but they mean so much that the efforts are well worth while. After cerebral incidents, sometimes actual apoplexies, sometimes injuries, occasionally serious effusions due to kidney diseases, there may be disturbance of motor functions. It is surprising how often training will enable the sufferer to use his muscles much better in these cases than at first seemed possible. I have seen a man who had lost most of his power for writing after a cerebral incident regain it as a consequence of being taught to write from his shoulder, instead of from the forearm as had been his custom.
Heart Training.—In recent years we have learned that training is not only good for the external muscles and enables them to do more work without discomfort, but that it is particularly beneficial to the heart muscle whenever that organ can respond to it favorably. At all of the heart cures in recent years, exercise of some kind or another is one of the important features and the failure of physicians generally to secure as good results while pursuing all the other methods followed at these cures, seems to show that exercise was probably the most important factor. Nauheim is the typical heart cure and there, besides the resisted movements in the bath, there is the graduated exercise of the walks around the town, all of which, owing to the situation, lead up hill. Walking up hill, even though it be a gradual ascent, might seem to be the worst possible exercise for heart patients, yet it proves eminently beneficial.