The Science of Human Nature: A Psychology for Beginners

by William Henry Pyle

As the different colors are due to different vibration frequencies of the ether, so different pitches of sound are due to differences in the rates of the air vibrations. The low bass notes are produced by the low vibration frequencies. The high notes are produced by the high vibration frequencies. The lowest notes that we can hear are produced by about twenty vibrations a second, and the highest by about forty thousand vibrations a second.

Other Sense Organs. We need not give a detailed statement of the facts concerning the other senses. In each case the sense organ is some special adaptation of the nerve-endings with appropriate apparatus in connection to enable it to be affected by some special thing or force in the environment.

In the case of taste, we find in the mouth, chiefly on the back and edges of the tongue, organs sensitive to sweet, sour, salt, and bitter. In the nose we have an organ that is sensitive to the tiny particles of substances that float in the air which we breathe in through the nose.

In the skin we find several kinds of sense organs that give us the sensations of cold and warmth, of pressure and pain. These are all special and definite sensations produced by different kinds of organs. The sense of warmth is produced by different organs from those which produce the sense of cold. These organs can be detected and localized on the skin. So, also, pain and touch or pressure have each its particular organ.

Within the body itself we have sense organs also, particularly in the joints and tendons and in the muscles. These give us the sensations which are the basis of our perception of motion, and of the position of the body and its members. In the semicircular canals of the inner ear are organs that give us the sense of dizziness, and enable us to maintain our equilibrium and to know up from down.

The general nature of the sense organs and of sensation should now be apparent. The nervous system reaches out its myriad fingers to every portion of the surface of the body, and within the body as well. These nerve-endings are specially adapted to receive each its particular form of stimulation. This stimulation of our sense organs is the basis or cause of our sensations. And our sensations are the elementary stuff of all our experience. Whatever thoughts we have, whatever ideas or images we have, they come originally from our sensations. They are built up out of our sensations or from these sensations as they exist in memory.

Defects of Sense Organs. The organs of sight and hearing are now by far the most important of our sense organs. They enable us to sense things that are at a distance. We shall therefore discuss defects of these two organs only. Since sensations are the primary stuff out of which mind is made, and since sight and hearing are the most important sense organs, it is evident that our lives are very much dependent on these organs. If they cannot do their work well, then we are handicapped. And this is often the case.

The making of the human eye is one of the most remarkable achievements of nature. But the making of a perfect eye is too big a task for nature. She never makes a perfect eye. There is always some defect, large or small. To take plastic material and make lenses and shutters and curtains is a great task. The curvature of the front of the eye and of the front and back of the crystalline lens is never quite perfect, but in the majority of cases it is nearly enough perfect to give us good vision. However, in about one third of school children the defect is great enough to need to be corrected by glasses.

The principle of the correction of sight by means of glasses is merely this:[1] When the focusing apparatus of the eye is not perfect, it can be made so by putting in front of the eye the proper kind of lens. There is nothing strange or mysterious about it. In some cases, the eye focuses the light before it reaches the retina. Such cases are known as nearsightedness and are corrected by having placed in front of the eyes concave lenses of the proper strength. These lenses diverge the rays and make them focus on the retina. In other cases, the eye is not able to focus the rays by the time they reach the retina. In these cases, the eyes need the help of convex lenses of the proper strength to make the focus fall exactly on the retina.

[1] The teacher should explain these principles and illustrate by drawings. Consult a good text in physiology. Noyes’ University of Missouri Extension Bulletin on eye and ear defects will be found most useful.