(i) Sweet-toned voice.

(j) Nasal tw.a.n.g.

(k) Fluency in speaking.

4. In each of the following reactions, decide whether the connection of stimulus and response is probably native or acquired:

Stimulus Response

(a) a sudden noise starting

(b) a bright light blinking

(c) a bright light shading your eyes

(d) cold putting on coat

(e) cold shivering

(f) sight of a ball reaching for it

(g) ball in the hand throwing it

(h) slipping righting yourself

(i) row of objects counting them

(j) insulting language anger

REFERENCES

Edward L. Thorndike, in Chapter I of his _Educational Psychology, Briefer Course_, 1914, gives a general survey of the native factors in mental life and behavior.

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Hollingworth and Poffenberger, in their _Applied Psychology_, 1917, devote Chapters II and III to the matter of mental heredity.

Norsworthy and Whitley, in their _Psychology of Childhood_, devote Chapters I and II to "original nature".

C. B. Davenport, in his _Heredity and Eugenics_, presents evidence of the importance of heredity in determining mental and moral traits.

Yerkes and Bloomfleld, in a short article in the _Psychological Bulletin_ for 1910, Vol. 7, pp. 253-263, under the t.i.tle, "_Do Kittens Instinctively Kill Mice?_", furnish a good ill.u.s.tration of the method employed in distinguishing native from acquired reactions.

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CHAPTER VI

INSTINCT

CONDUCT AS DETERMINED BY NATIVE REACTION-TENDENCIES

Instinct is native behavior. It is contrasted with habit, knowledge, or anything in the way of learned reactions. When the mother wasp gathers a store of food suitable for young wasps, lays eggs beside the food and covers the whole with a wall of mud, we know that her behavior is instinctive because she has had no possible chance to learn from older wasps. She has never seen a wasp's nest made, for when the last preceding crop of nests was being made she was herself an unhatched egg. Therefore, she cannot possibly know the use of the nest with its eggs and store of food. She has no "reason" for building the nest, no ulterior purpose, but is impelled to build the nest, simply and solely for the sake of doing just that thing. Thus instinct is contrasted with calculated or reasoned action as well as with learned action. Calculated action is based on knowledge of cause and effect, and this knowledge is acquired by the individual in the course of his experience; but instinct is not based on the individual's experience, but only on his native const.i.tution.

The case of the baby eating is exactly the same as that of the wasp.

The baby has not learned to eat, he knows nothing of the use of food and therefore has no ulterior purpose in eating, he does not reason about the matter, but eats simply because hunger is a native impulse to eat. {106} Eating is an end in itself to a hungry baby, and not a means to some further end; and that is what eating continues to be even to the hungry adult, however much he may learn about the use of food in maintaining life. From a broad philosophical point of view, instinct may be seen to work towards some great end, such as the preservation of the individual or the propagation of the race, but from the individual's own point of view, it is directed simply towards the performance of some particular act, or the accomplishment of some particular result.

If instinct, as a collective term, means native behavior, "an instinct" is a unit of such behavior. Or, it is some unit of native organization that equips the individual to behave in a certain way.

Different species of animals have different instincts, i.e., they are differently organized by nature. The differences of organization lie partly in the equipment of sense organs, partly in the equipment of motor organs, and partly in the nerves and nerve centers that, being themselves aroused by way of the sense organs, in turn arouse the motor organs.

The dependence of instinct on sensory equipment becomes clear when we think of animals possessing senses that human beings lack. The instinct of dogs to follow the scent depends on their keen sense of smell. Bees have something akin to a sense of taste in their feet, and follow their own trails by tasting them. Fishes have special sense organs along their sides that are stimulated by water currents, and it is in response to this stimulus that the fish instinctively keeps his head turned upstream.

The dependence of instinct on motor equipment is still more obvious.

The flying instinct of birds depends on the possession of wings, and the swimming instinct of the seal depends on the fact that his limbs have the peculiar form of flippers. The firefly instinctively makes flashes of light, {107} and the electric eel instinctively discharges his electric organ and gives his enemy a shock.

But the core of an instinct is to be sought in the nerve centers, since it is there that the coordination of the muscles is accomplished. A wing or flipper would be of no use unless its muscles were excited to action by the nerve centers, and it would be of very little use unless the nerve centers were so organized as to arouse the muscles in a certain combination, and with a certain force and rhythm.

In terms of the nervous system, an instinct is the activity of a team of neurones so organized, and so connected with muscles and sense organs, as to arouse certain motor reactions in response to certain sensory stimuli.

The Difference Between an Instinct and a Reflex

What we have said regarding instinct thus far could equally well be said of reflex action. A reflex is a native reaction, and it is taken care of by a team of neurones in the way just stated. We might speak of a reflex as "instinctive", using this adjective as equivalent to "native"; but we should shrink for some reason from speaking of the pupillary reflex to light as an instinct, or of the "knee jerk instinct", or the "swallowing instinct", or the "flexion instinct".

There is some difference between the typical reflex and the typical instinct, though it is not very obvious what the difference is.

The typical reflex is a much simpler act than the typical instinct, but it is impossible to separate the two cla.s.ses on this basis. At the best, this would be a difference of degree and not of kind. Among reflexes, some are simpler than others, but even the simplest is compound in the sense of being a coordinated movement. The knee jerk is simpler than the flexion reflex, and this is simpler than the scratch {108} reflex, which consists of a rapid alternation of flexion and extension by one leg, while the other is stiffly extended and supports the trunk. Coughing, which would be called a reflex rather than an instinct, consists of a similar alternation of inspiration and forced expiration, and swallowing consists of a series of tongue, throat and gullet movements. These compound reflexes show that we cannot accept the simple definition that is sometimes given for an instinct, that it is a compound of reflexes. Such a definition would place coughing and swallowing among the instincts, and so do violence to the ordinary use of the word. In point of complexity, we find a graded series ranging from the pupillary reflex at one extreme to the nesting or mating instinct at the other, and no sharp line can be drawn on this score between the reflexes and the instincts.

Another distinction has been attempted on the basis of consciousness.

Typically, it may be said, a reflex works automatically and unconsciously, while an instinct is consciously impulsive. The reflex, accordingly, would be an unconscious reaction, the instinct a conscious reaction. But this distinction also breaks down on examination of cases. The pupillary reflex, to be sure, is entirely unconscious. But the flexion reflex is a little different. When unimpeded, it occurs so promptly that we are scarcely aware of the painful stimulus before the reaction has occurred. But let the reaction be hindered--either voluntarily or, for instance, by the foot being seized and held--and a strong conscious impulse is felt to pull the leg away; so that here the flexion reflex would belong among the instincts, according to the proposed distinction.

Similar remarks would apply equally well to coughing, since a strong impulse to cough is felt if the coughing movement is checked.

Sneezing, a protective reflex, is usually a slow reaction, giving time for a conscious impulse to {109} sneeze before the reaction takes place. The same is true of scratching and of swallowing, and of a number of other reflexes. In short, it is impossible to draw a satisfactory line between reflexes and instincts on the basis of conscious impulse.

These cases point the way, however, to what is probably the best distinction. It was when the flexion reflex was _delayed_ that it began to look like an instinct, and it was because sneezing was a _slow_ response that it had something of the character of an instinct.

Typically, a reflex is a prompt reaction. It occurs at once, on the occurrence of its stimulus, and is done with. What is characteristic of the instinct, on the contrary, is the persisting "tendency", set up by a given stimulus, and directed towards a result which cannot be instantly accomplished.

An Instinct Is a Native Reaction-Tendency

We would propose, then, to consider an instinct as an inner adjustment, or tendency to reaction. It is this, rather than just a reaction. When a stimulus promptly arouses a reaction, and that ends the matter, we speak of reflex action--provided, of course, the connection between stimulus and response is native. But when a stimulus sets up a tendency to a reaction that cannot be immediately executed, or towards an end-result which cannot immediately be reached, and when the tendency so aroused persists for a time in activity, and gives rise to preparatory reactions, then we speak of instinct.

The "broody" hen makes a good picture of instinct. When in this condition she responds to a nestful of eggs, as she does not at other times, by sitting persistently on them and keeping them covered. She is in a certain "organic state" that facilitates this response. In the absence {110} of any nestful of eggs, she shows a peculiar restless behavior that indicates to one who knows hens that this one "wants to set." The tendency that has been awakened in her cannot be satisfied by any momentary act, but persists and governs her actions for a considerable period.

The nesting instinct of birds affords a still more complete example.

The end-result here, the finished nest, cannot be instantly had, and the pair of birds keep on gathering materials and putting them together until this end-result is present before their eyes. It is not necessary to suppose that the birds have any plan or mental image of what the nest is to be like; probably not. But their state, in the nest-building season, is such that they are impelled to build, and the tendency is not quieted till the completed nest is there.