The experiment was as follows: Chickens were taken at the time of hatching, and some allowed to peck from the first, while others were kept in a dark room and not allowed to peck. When the chickens were taken out of the dark room at the end of one, two, three, and four days, it was found that in a few hours they were pecking as well as those that had been pecking from birth. It seems probable, if we may judge from our limited knowledge, that in the human child, activities are for the most part dependent upon the age of the child, and upon the state of development of the nervous system and of the organs of the body.

Significance of Inherited Tendencies. Although human nature is very complex, although human action nearly always has some element of habit in it, nevertheless, inborn tendencies are throughout life powerful factors in determining action. This will at once be apparent if we consider how greatly we are influenced by anger, jealousy, love, fear, and competition. Now we do not have to learn to be jealous, to hate, to love, to be envious, to fight, or to fear. These are emotions common to all members of the human race, and their expression is an inborn tendency. Throughout life no other influences are so powerful in determining our action as are these. So, although most of our detailed actions in life are habits which we learn or acquire, the fundamental influences which decide the course of our action are inherited tendencies.

Classification of Instincts. For convenience in treatment the instincts are grouped in classes. Those instincts most closely related to individual survival are called individualistic instincts. Those more closely related to the survival of the group are called socialistic. Those individualistic tendencies growing out of periodic changes of the environment may be called environmental instincts. Those closely related to human infancy, adapting and adjusting the child to the world in which he lives, may be called adaptive. There is still another group of inherited tendencies connected with sex and reproduction, which are not discussed in this book.

We shall give a brief discussion of the instincts falling under these various classes. It must be remembered, however, that the psychology of the instincts is indefinite and obscure. It is difficult to bring the instincts into the laboratory for accurate study. For our knowledge of the instincts we are dependent, for the most part, on general observation. We have had a few careful studies of the very earliest years of childhood. However, although from the theoretical point of view our knowledge of the instincts is incomplete, it is sufficient to be of considerable practical value.

The Individualistic Instincts. Man’s civilized life has covered but a short period of time, only a few hundred or a few thousand years. His pre-civilized life doubtless covered a period of millions of years. The inborn tendencies in us are such as were developed in the long period of savage life. During all of man’s life in the time before civilization, he was always in danger. He had many enemies, and most of these enemies had the advantage of him in strength and natural means of defense. Unaided by weapons, he could hardly hold his own against any of the beasts of prey. So there were developed in man by the process of natural selection many inherited responses which we group under the head of fear responses.

Just what the various situations are that bring forth these responses has never been carefully worked out. But any situation that suddenly puts an individual in danger of losing his life brings about characteristic reactions. The most characteristic of the responses are shown in connection with circulation and respiration. Both of these processes are much interfered with. Sometimes the action is accelerated, at other times it is retarded, and in some cases the respiratory and circulatory organs are almost paralyzed. Also the small muscles of the skin are made to contract, producing the sensation of the hair standing on end. Just what the original use of all these responses was it is difficult now to work out, but doubtless each served some useful purpose.

Whether any particular situations now call forth inherited fear responses in us is not definitely established. But among lower animals there are certain definite and particular situations which do call forth fear responses. On the whole, the evidence rather favors the idea of definite fear situations among children. It seems that certain situations do invariably arouse fear responses. To be alone in the dark, to be in a strange place, to hear loud and sudden noises, to see large, strange animals coming in threatening manner, seem universally to call forth fear responses in children.

However, the whole situation must always be considered. A situation in which the father or mother is present is quite different from one in which they are both absent. But it is certain that these and other fears are closely related to the age and development of the child. In the earlier years of infancy, certain fears are not present that are present later. And it can be demonstrated that the fears that do arise as infancy passes on are natural and inherited and not the result of experience.

Few of the original causes of fear now exist. The original danger was from wild animals chiefly. Seldom are we now in such danger. But of course this has been the case for only a short time. Our bodies are the same sort of bodies that our ancestors had, therefore we are full of needless fears. During the early years of a child’s life, wise treatment causes most of the fear tendencies to disappear because of disuse. On the other hand, unwise treatment may accentuate and perpetuate them, causing much misery and unhappiness. Neither the home nor the school should play upon these ancestral fears. We should not try to get a child to be good by frightening him; nor should we often use fear of pain as an incentive to get a child to do his work.

Man has always been afraid, but he has also always been a fighter. He has always had to fight for his life against the lower animals, and he has also fought his fellow man. The fighting response is connected with the emotions of anger, envy, and jealousy. A man is angered by anything that interferes with his life, with his purposes, with whatever he calls his own. We become angry if some one strikes our bodies, or attacks our beliefs, or the beliefs of our dear friends, particularly of our families. The typical responses connected with anger are such as faster heart-beat, irregular breathing, congestion of the blood in the face and head, tightening of the voluntary muscles, particularly a setting of the teeth and a clinching of the fists. These responses are preparatory to actual combat.