Psychology by Robert S. Woodworth (top rated ebook readers .TXT) 📕

and Experimental Study of Homing, published by the Carnegie Institution of Washington, 1915.

Interesting examples of changed organic states affecting the behavior of unicellular animals are given by Jennings in his Behavior of the Lower Organisms, 1906, and by Margaret F. Washburn in The Animal Mind, 2nd edition, 1917, pp. 246-257.

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CHAPTER V

NATIVE AND ACQUIRED TRAITS

SOME RESPONSES ARE PROVIDED BY NATURE, WHILE OTHERS HAVE TO BE LEARNED BY EXPERIENCE

John Doe is a strongly built man, over six feet high, with big bones and muscles, erect, vigorous, with plenty of color in his face, dark-haired, blue-eyed, clean-shaven, with a scar on his cheek, broad face and large ears. He is easy-going, even-tempered, fond of children and also of women, rather slangy and even profane in his talk, has a deep, sonorous voice and can carry the bass in a chorus. He is handy with tools, can drive or repair an automobile, is a fairly good carpet salesman, but much prefers out-of-door work. Rather free in spending his money, he has never run into debt except on one occasion, which turned out badly for him. Which of these traits of John Doe are native and which are acquired? How far are his physical, mental and moral characteristics the result of his "original nature" and how far have they been ingrained in him or imposed upon him by his training and environment?

The distinction between native and acquired is clearest in the field of anatomy. Hair color and eye color are evidently native, and so, in the main, is the size of the body, though undoubtedly growth may be stunted by poor nutrition, and the individual fail to reach his "natural" height and weight. On the other hand, scars, tan, and the after-effects of disease or injury, are evidently acquired. Of movements, the native character of the reflexes has already been noted, and it is clear that skill in handling tools or {90} managing the voice is learned, though the individual may have a natural aptitude for these performances. Temperament and emotional traits we usually think of as belonging to a man's "nature", though we have to admit that a naturally cheerful disposition may be soured by ill treatment. On the other hand, while we reckon habits, such as profanity, or free spending, or an erect carriage, as belonging with the acquired traits, we know that some natures are prone to certain habits, and other natures to other habits. Thus the effects of "nature" and "experience" are almost inextricably interwoven in the behavior of an adult person.

Difficult as it certainly is to separate the native from the acquired in human action, the attempt must be made. We cannot dodge so fundamental a problem. Scientifically it is important as the starting-point of a genetic study; we must know where the individual starts in order to understand the course of his development. Practically it is important because there is reason to believe that native traits are deeply seated and not easily eradicated, even though they can be modified and specialized in different ways. If a habit is not simply a habit, but at the same time a means of gratifying some natural tendency, then it is almost imperative to find a substitute gratification in order to eliminate the habit. The individual's nature also sets limits beyond which he cannot be brought by no matter how much training and effort; and this is true of mental development as well as of physical.

The Source of Native Traits

"Native" means a little more than "congenital." A child may be born blind, having been infected by disease germs shortly before birth; he may be congenitally an idiot because of head injury during a difficult birth; or his mentality may have been impaired, during his uterine life, by {91} alcohol reaching his brain from a drunken mother. Such traits are congenital, but acquired. Native traits date back to the original constitution of the child, which was fully determined at the time when his individual life began, nine months before birth. The "fertilized ovum", formed by the combination of two cells, one from each of the parents, though microscopic in size and a simple sphere in shape, somehow contains the determiners for all the native or inherited traits of the new individual.

It is very mysterious, certainly. This microscopic, featureless creature is already a human individual, with certain of its future traits--those that we call "native"--already settled. It is a human being as distinguished from any other species, it is a white or colored individual, male or female, blonde or brunette, short or tall, stocky or slender, mentally gifted or deficient, perhaps a "born" musician or adventurer or leader of men. These and all other native traits are already determined and latent within it; and the only question, regarding such traits, is whether the environment is going to be such as to enable this young individual to live and mature and unfold what is latent within it.

Reactions Appearing at Birth Must Be Native

For the first few months of the individual's existence, sheltered as it is within the mother's body, there is no chance for any acquisition, except of certain abnormalities such as were alluded to above. What occurs during this prenatal period is natural development, not learning or any effect of experience. The traits displayed by the new-born child are, accordingly, native traits. His breathing, crying, starting at a noise, squirming, stretching, grasping, sucking and swallowing, and other movements made from birth on, are to be counted as native reactions, that is to say, as {92} reactions executed by sensory, muscular and nervous machinery that have become ready for use by the mere process of natural growth. This is the first and clearest sign of a native trait, that it shall appear at birth.

Reactions That Cannot Be Learned Must Be Native

But native traits continue to make their appearance as the child's development proceeds after birth. Inherited anatomical traits, like stature and build, hair color, beard, and shape of nose, though certainly determined by native constitution, do not fully make their appearance till maturity. In fact, what does maturity mean, except that the natural characteristics have finally reached their complete development? And it is as true of internal structure as of external, that natural development, far from being complete at birth, keeps on till maturity. The neurones continue to grow, and their synapses in the nerve centers to become closer knit, just by virtue of natural growth; and thus reflex arcs, and other reaction machinery, one by one reach the ready-to-use stage during the individual's growing-up, especially during the first few years. With the growth to a functional condition of their sensori-neuro-muscular mechanisms, mental and motor reactions that are native, though not present at birth, make their appearance. The native intelligence of the child gradually unfolds, likewise his special native "gifts" and his inherited emotional and impulsive traits.

Of course it is more difficult to make sure that a trait is native when it does not appear till some time after birth, for the chance of acquiring it by a process of learning has to be taken into account. If you can so control the conditions under which the young individual grows as to eliminate the possibility of learning a certain act, then you can {93} make sure whether the act is acquired or provided by the native constitution.

Experimental Detection of Native Reactions

Take the question whether birds learn to fly or simply come to fly when their natural development has gone far enough. The newly hatched bird cannot fly; its muscles are not strong enough, its wings are not feathered, and its nerve mechanism for coördinating the wing movements has still some growth to make before being ready for use. But, under ordinary conditions, the young bird has some chance to learn flying, by watching the old birds fly and by trying and gradually getting the motion. The old birds, after a time, push the young ones from the nest and seem, to our eyes, to be teaching them to fly. Experiment enables us to decide the question. One of the earliest experiments in animal psychology was made by Spalding in 1873. He took newly hatched birds from the nest and shut each one separately in a little box that gave it no chance to stretch its wings or to see other birds fly. Here he fed and cared for them till the age at which flying usually begins, and then released them. Off they flew, skilfully managing wings and tail, swooping around the trees and soon disappearing from sight. A very successful experiment!--and conclusive. The little birds had had no chance to learn to fly, yet they flew. Flying must have come to them in the natural course of growth.

Compare with this experiment another one no less successful, though it turned out differently. To discover whether the song of the oriole is fixed by nature or learned by imitation, Scott took some little ones, just hatched, and brought them up away from older birds. After a time, when growth had advanced to a certain stage, the birds began {94} to sing. The elementary notes and rattles characteristic of the oriole made their appearance, but were combined in unusual ways, so that the characteristic song of the oriole did not appear, but a new song. When these birds had grown up in the laboratory, other new-hatched orioles were brought up with them, and adopted this new song; so that the laboratory became the center for a new school of oriole music. The experiment showed that the elements of the oriole's song were provided by nature, while the combination of these elements was acquired by imitation.

Probably this last is about the result one would get in the analogous case of human speech, if a similar experiment should be tried on children. Without an experiment, we have certain facts that point to a conclusion. The child uses his vocal organs from birth on; and before he reaches the age when he imitates the speech of others, he produces various vowels and consonants, and even puts them together into simple compounds, as "da-da" and "goo-goo." So far, deaf children do about the same as others, affording additional evidence that so much of speech is native. To get real speech, however, further combinations of the speech movements must be made, and the combinations (words) must have meaning attached to them. These higher achievements are evidently the result of learning, since the child uses the words that it hears spoken, and attaches the same meanings to them as people do about it. The child comes to speak the language of those about it, without regard to the speech of its ancestors. His "native language" is therefore acquired, though the elements of vocal utterance are truly native, and apparently are alike all over the world without regard to the various languages spoken.

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Is Walking Native or Acquired?

As another example of this same general problem of distinguishing native from acquired reactions, and of the kind of evidence that throws light on the problem in the absence of direct experiment, let us consider the child's walking. Does the child learn to walk, or does it simply come to walk when its natural development has gone far enough? We think the child learns to walk because it begins very imperfectly and usually takes several weeks before it can be described as really walking of itself. We even think we teach it to walk, though when we examine our teaching we soon convince ourselves that we do not know how we walk, and that what we are doing with the baby is to stimulate and encourage him to walk, protect him from hurting himself, etc., rather than teaching him as we later teach the child to write. An experiment to settle the matter might be conducted along the lines of Spalding's experiment on the young birds. We might prevent the baby from making any