The mating instinct, in unsophisticated members of the human species, is another perfect example. So is the hunting instinct in a dog; when this instinct is aroused, the animal makes a lot of movements of various sorts, responses to various particular stimuli, but evidently these movements are not sufficient to quiet the tendency, for they continue till the prey is captured. The behavior of a gregarious animal when separated from his fellows shows the same sort of thing.

Take a young chick out of the brood and fence it away from the rest.

It "peeps" and runs about, attacking the fence at different points; but such reactions evidently do not bring satisfaction, for it varies them until, if a way out of the inclosure has been left, it reaches the other chicks, when this series of acts terminates, and gives way to something quite different, such as pecking for food.

The persisting tendency does not produce the series of movements all by itself, but, as was explained in speaking of tendencies in general, cooperates with sensory stimuli in producing them. Clearly enough, the nest-building bird, {111} picking up a twig, is reacting to that twig.

He does not peck at random, as if driven by a mere blind impulsion to peck. He reacts to twigs, to the crotch in the tree, to the half-built nest. Only, he would not react to these stimuli unless the nesting fit were on him. The nest-building tendency favors response to certain stimuli, and not to others; it facilitates certain reactions and inhibits others. It facilitates reactions that are _preparatory_ to the end-result, and inhibits others.

Fully and Partially Organized Instincts

Insects afford the best examples of very highly organized instincts.

Their behavior is extremely regular and predictable, their progress towards the end-result of an instinct remarkably straightforward and sure. They make few mistakes, and do not have to potter around. By contrast, the instincts of mammals are rather loosely organized.

Mammals are more plastic, more adaptable, and at the same time less sure; and this is notably true of man. It would be a mistake to suppose that man has few instinctive tendencies; perhaps he has more than any other creature. But his instinctive behavior has not the hard-and-fast, ready-made character that we see in the insects. Man is by all odds the most pottering, hem-and-hawing of animals. Instinct does not lead him straight to his goal, but makes him seek this way and that till he finds it. His powers of observation, memory and thought are drawn into the game, and thus instinct in man is complicated and partly concealed by learning and reasoning.

For example, when an insect needs a nest, it proceeds in orderly fashion to construct a nest of the pattern instinctive to that species of insect; but when a man needs a home, he goes about it in a variable, try-and-try-again {112} manner, scheming, experimenting, getting suggestions from other people, and finally producing--a dugout, a tree house; a wigwam, a cliff dwelling--something that differs altogether from many other human habitations, except in the fact that it is a habitation and thus satisfies a need which is undoubtedly as instinctive in man as in the insect.

A fully organized instinct is one where the necessary preparatory reactions are linked up closely with the main reaction-tendency, so that, once the main tendency is aroused to activity, the preparatory reactions follow with great sureness. The main team of neurones is closely connected with the subordinate teams that give the preparatory reactions; and these connections do not have to be acquired by experience and training, but are well formed by native growth. Just the right preparatory reactions are linked to the main tendency, so that the whole series of acts is run off with great regularity.

In a loosely organized instinct, the main tendency is not firmly linked with any specific preparatory reactions, but is loosely linked with a great many preparatory reactions, and so gives quite variable behavior, which, however, leads on the whole towards the main goal.

While a creature under the spell of a fully organized instinct is busy, one driven by a loosely organized instinct may be better described as restless. He tries this thing and that, and goes through the kind of behavior that is called "trial and error". A closely knit instinct, then, gives a perfectly definite series of preparatory reactions, while a loosely organized instinct gives trial and error behavior. We shall see later how trial and error furnishes a starting point for learning, and how, in an animal that can learn, those among the trial-and-error reactions that are actually preparatory to the end-result become firmly attached to the main tendency, so that what was by native const.i.tution a loosely {113} organized instinct may become, through the individual's experience, a closely organized habit. If a man has occasion to build himself many homes, he comes, after a while, to build almost as uniformly and surely as an insect.

Instincts Are Not Ancestral Habits

The theory of inheritance of acquired traits has gone by the board; biologists no longer accept it. Such traits as an individual's tanned skin acquired by living in the tropics, h.o.r.n.y hands acquired by hard labor, immunity to measles acquired by having measles, big muscular development acquired by gymnastics, are not transmitted by heredity to the children of the individual who acquired these traits.

Nor are acquired behavior traits transmitted by heredity. Learned reactions are not so transmitted, knowledge is not, acquired skill is not. Learn to cook, to typewrite, or pilot an airplane as perfectly as possible, and your child will still have to learn all over again. You may make your experience valuable to him by _teaching_ him, but not in the way of heredity.

Language affords a good test of this matter. A child's parents, and all his ancestors for many generations, may have spoken the same language, but that does not relieve the child of the necessity of _learning_ that language. He does not inherit the language habits of his ancestors. He has no native tendency to say "dog", or "chien", or "hund", on sight of this animal. Here in America we have children born of stocks that have spoken foreign languages for many generations; but English becomes their "native tongue" after a generation or two here, that is to say, as soon as the child hears English from infancy.

In short, there is no likelihood whatever that any instinct {114} ever originated out of a habit or learned reaction. If we could believe it had so originated, that would furnish an easy explanation of the origin of an instinct; but it is contrary to all the known facts.

Instincts Not Necessarily Useful in the Struggle for Existence

Some of the best-known instincts, such as feeding or mating--or hunting, or flight from danger, or the hibernation of frogs--are so essential for the survival of the individual or the propagation of the next generation that we tend to a.s.sume that all instinctive behavior has "survival value", value, that is, towards the survival of the individual or of the race. But this is an a.s.sumption, and it seems not to be borne out by actual observations of instinctive behavior, since, along with the definitely useful reactions, others occur that would seem to have no survival value. Perhaps the crowing of the rooster at dawn would be a case in point; or the elaborate bowing that is observed in some kinds of birds. And there are the less definite, rather random movements of squirming, kicking, running about, wrinkling up the face, etc., that appear in young animals. We may well hesitate before definitely a.s.serting that these movements are of no use for survival, but at least their use is not obvious, and there is no reason for a.s.suming that all instinctive behavior must necessarily be useful.

To be sure, the "struggle for existence" would eliminate individuals who behaved in ways that seriously handicapped them in procuring food or escaping from enemies; and therefore we should not expect to find really harmful instincts preserved in the race. But a mode of behavior might be neutral in this respect, or even slightly disadvantageous, and yet not be weeded out unless the struggle for existence were very keen.

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The main point is that the psychologist should take instinctive behavior as he finds it, and not allow himself to be prejudiced by the a.s.sumption that instinct must necessarily be useful. That has to be shown in each case, not a.s.sumed at the outset.

The So-called Instincts of Self-preservation and of Reproduction

You will hear it stated, by some, that there are just two instincts, and that all instinctive behavior belongs under the head of one or the other of these two. The one is the instinct to preserve one's individual life, and the other is the instinct to propagate the species. Mating, nesting and care of the young come under the reproductive instinct, while feeding, flight from danger, and shunning extreme heat or cold are modes of self-preservation. This seems logical enough, but it is very bad psychology. It amounts to a cla.s.sification of native reactions from an external point of view, without any consideration of the way the individual is organized.

Perhaps the most obvious objection to these two supposedly all-inclusive instincts is found in what has just been said, to the effect that some instinctive behavior has no known survival value.

This amounts to saying that some instincts do not serve either the preservation of the individual or the propagation of the species; and such a statement is probably true, especially of human instincts.

But even if this objection should not hold, there is another, more radical one. Neither of these two big "instincts" is a behavior unit in any sense. Take the "instinct of self-preservation", for example.

It would certainly have to include both feeding and escape from danger. But feeding and flight from danger do not belong in a single series {116} of acts; they are two distinct series, and represent two distinct tendencies. So distinct are they that, as we shall see in the next chapter, they are antagonistic. If the danger-avoiding tendency is aroused, the whole feeding and digestive activity is checked for the time being. The two instincts are antagonistic, in their actual operation; throw one into action, and you throw the other out. It is only from an external point of view that the two can be cla.s.sed together; in the organization of the individual they are entirely separate.

Not much different is the "instinct of reproduction". In birds, to be sure, there is a fairly continuous series of reactions, that begins with mating, continues with nesting, laying eggs and incubating them, and ends in the care of the young birds. But in mammals there is no such continuous series of reproductive acts, but mating comes to a close and an interval elapses in which there is no behavior going on that has anything to do with reproduction.

Before giving a detailed list of the various human instincts, we shall do well to consider emotion, which is closely bound up with instinct.

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EXERCISES

1. Outline the chapter.

2. Explain the differences between these three;

Action governed by instinct.

Action governed by habit.

Action governed by deliberation.

3. What is the objection to each of the following expressions?

(a) "The ex-soldier instinctively saluted when he met an officer in the street."

(b) "The bee knows by instinct how to construct the honeycomb."

4. Why is it so difficult to find a valid distinction between instinct and reflex action?

5. Why are instincts more universal and uniform than habits?

6. How is instinct an important matter to consider in a study of human motives?

7. Show how the behavior of a hungry child of six or eight years fits the picture of a "loosely organized instinct".

REFERENCES

William James in his _Principles of Psychology_, 1890, has a very stimulating chapter on instinct, in Vol. II, pp. 383-441.

John B. Watson, in Chapters IV and V of his _Behavior_, 1914, gives a good account of the instincts of animals.

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CHAPTER VII