The sense of Touch is the simplest and primal sense. Long before the lower forms of life had developed the higher senses, they had evidenced the sense of Touch or Feeling. Without this sense they would have been unable to have found their food, or to receive and respond to outside impressions. In the early forms of life it was exercised equally by all parts of the body, although in the higher forms this sense has become somewhat localized, as certain parts of the body are far more sensitive than are others. The skin is the seat of the sense of Touch, and its nerves are distributed over the entire area of the skin. The hand, and particularly the fingers, and their tips, are the principal organs of this sense.
The acuteness of Touch varies materially in different parts of the body. Experiments have shown that a pair of compasses would register impressions as a very slight distance apart when applied to the tip of the tongue. The distance at which the two points could be distinguished from one point, on the tip of the tongue, was called “one line.” Using this “line” as a standard, it was found that the palmar surface of the third finger registered 2 lines; the surface of the lips 4 lines, and the skin of the back, and on the middle of the arm or thigh, as high as 60 lines The degree of sensitiveness to Touch varies greatly with different individuals, some having a very fine sense of touch in their fingers, while others manifested a very much lower degree.
In the same way, there is a great difference in the response of the fingers to weight–a great difference in the ability to distinguish the difference of the weight of objects. It has been found that some people can distinguish differences in weight down to very small fractions of an ounce. Fine distinctions in the differences in temperature have also been noticed.
The sense of touch, and its development has meant much for Man. It is the one sense in which Man surpasses the animals in the matter of degree and acuteness. The animal may have a keener smell, taste, hearing and sight, but its sense of Touch is far beneath that of Man. Anaxagoras is quoted as saying that “if the animals had hands and fingers, they would be like men.”
In developing the sense of Touch, the student must remember that Attention is the key to success. The greater the amount of Attention the greater the degree of development possible in the case of any sense. When the Attention is concentrated upon any particular sense, the latter becomes quickened and more acute, and repeated exercise, under the stimulus of Attention, will work wonders in the case of any particular sense. And on the other hand, the sense of touch may be almost, or completely inhibited, by firmly fixing the Attention upon something else.
As an extreme proof of this latter fact, the student is asked to remember the fact that men have been known to suffer excruciating torture, apparently without feeling, owing to the mind being intently riveted upon some idea or thought. As Wyld has said, “The martyr borne above sensuous impressions, is not only able to endure tortures, but is able to endure and quench them. The pinching and cutting of the flesh only added energy to the death song of the American Indian, and even the slave under the lash is sustained by the indignant sense of his wrongs.”
In the cases of persons engaged in occupations requiring a fine degree of Touch, the development is marvelous. The engraver passes his hand over the plate, and is able to distinguish the slightest imperfection. And the handler of cloth and fabrics is able to distinguish the finest differences, simply by the sense of touch. Wool sorters also exercise a wonderfully high degree of fineness of touch. And the blind are able to make up for the loss of sight by their greatly increased sense of Touch, cases being recorded where the blind have been able to distinguish color by the different “feel” of the material.