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1. Complete the following outline of the chapter, by filling in main headings to fit the subordinate headings that are given below:
A. _________
(1) It keeps close to the facts.(2) It has room for introspective as well as behavior study.(3) It can be applied practically.
B. _________
(1) A stimulus is typically external, a purpose internal.(2) A stimulus typically acts for a moment, a purpose persists for some time.(3) A stimulus is not directed towards a result, a purpose is so directed.
C. _________
(1) Organic or physiological states that predispose towards certain forms of behavior.(2) Inner adjustments towards certain results, without foresight of the results.(3) Conscious purpose.
D. _________
(1) They are aroused by stimuli.(2) They persist for a time.(3) They influence the response to other stimuli.
E. _________
(1) They are neural rather than chemical.(2) They amount to a preparation or readiness for a certain response.(3) They persist sometimes for only a few seconds, sometimes for many minutes at least.
F. _________
(1) A whole series of acts may be set going by a single stimulus.(2) The series comes to an end when a certain result has been reached.(3) Each act in the series is a response to some particular stimulus, and yet would not be aroused by that stimulus except for the active adjustment towards the end-result.{87}(4) The end-result cannot be reached until a particular stimulus helps the adjustment to arouse the end-reaction.(5) The preliminary acts in the series bring the required stimulus that can give the end-reaction.
G. _______
(1) It may be kept active by a continuing peripheral stimulus.(2) It may be unable to discharge fully because its main path of discharge is blocked.
H. ______
(1) The main center has minor connections with other centers, in addition to its main path of discharge.(2) The persisting activity of the main center influences other centers by way of facilitation and inhibition.
2. Fill in the blanks in the following paragraph:
"A motive or (1) is a reaction that has not yet come off. It has been (2) by some stimulus, and it tends towards a certain (3), which however it is unable of itself to produce, but requires the assistance of another (4) which is not yet present. The motive gives rise to (5) responses, which, if (6), finally bring the required (7), and this, combined with the (8) arouses the (9), and so brings the whole (10) of acts to a close."
3. Cite cases illustrating the importance of preparatory adjustment
(a) for securing prompt reaction, and(b) for securing keen observation.
4. Cite a case where some need or desire gives rise to a series of preparatory reactions.5. Cite a case where a need or desire leads to the omission (inhibition) of acts that would otherwise have occurred.6. What is meant by the last sentence in the chapter?7. An experiment on the "delayed reaction". Take two sheets of paper, and on each write the letters A, B, C, D, E, and F, scattering them irregularly over the sheet. The task, in general, is now to take aim at one of the letters, while your hand, holding a pencil, is raised to the side of your head, and then to close the eyes and strike at the letter aimed for. First aim at A, and mark the point hit with an a, then the same with B, and so on. With the first sheet, strike as soon as you have got your aim and closed your eyes; but with the second sheet, aim, close your eyes, and count ten slowly before striking, keeping the eyes closed till the stroke has been made. Two sorts of observation should now be made: first, introspective--record at once what you can of the way you kept your aim during the delay. Second, objective--measure the errors, and determine how much the delay affected your aim. What conclusions can you draw from the experiment?
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On the "delayed reaction", see Walter S. Hunter, "The Delayed Reaction in Animals and Children",Behavior Monographs, No. 6, 1913. A brief summary of this work can also be found in Hunter'sGeneral Psychology, 1919, pp. 31-33.
On the homing of pigeons and terns, see Watson and Lashley,An Historical 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 hisBehavior of the Lower Organisms, 1906, and by Margaret F. Washburn inThe Animal Mind, 2nd edition, 1917, pp. 246-257.
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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.
"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.
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.
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.
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 tolearnflying, 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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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 simplycometo 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 knowhowwe 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 attempt to walk till it had fully reached the normal age for walking, and then turn it loose and see whether it walked of itself.
Such an experiment has never been made under strict laboratory conditions; but here is a well-attested case that approximates to an experiment. A little girl of seven months, a very active child, seemed to want to get on her feet; but the doctor decided that her feet were too small to use, and directed that she be put back in long dresses. For four months she was kept in long dresses, and great care was exercised never to place her on the floor without them. Then, one day, she was set down without her dress, and immediately up she got and walked; and from that moment she was very agile on her feet.
Another rather different case, but tending towards the{96}same conclusion, is that of a little girl who, in contrast to the preceding, gave her parents some anxiety because, up to the age of seventeen months, she wouldn't walk. She would stand holding on, but not trust herself to her feet alone. One noon her father came in from his work and, removing his cuffs, laid them on the table. The little girl crept to the table, and raised herself to a standing position, holding on to the table. She then took a cuff in one hand, and inserted the other hand into it, thus, for the first time, standing unsupported. She put on the other cuff in like manner, and then marched across the room, as proud as you please. For a few days she could walk only with cuffs, but after that was able to dispense with them. There are a few other cases, differing in details, but agreeing on the main point, that the baby walked well on its first trial and went through nothing that could properly be interpreted as a process of learning.
It would really be very surprising if the human infant were left to learn locomotion for himself, while all other animals have this power by nature. Just because the human infant matures slowly, and learns a vast deal while maturing, is no reason for overlooking the fact that it does mature, i.e., that its native powers are gradually growing and reaching the condition of being ready for use. The most probable conception of "learning to walk," in the light of the evidence, is about as follows. At the age when the child's bones and muscles have become strong enough for walking, the nerve connections for coördinating this complex movement have also just about reached the stage of development when they are ready for business. The numerous synapses in the nerve centers that must be traversed by nerve currents in order to arouse the muscles to this particular act are not, we may suppose, all ready at the same instant, and it takes some little time for them to pass from{97}the stage when they will first conduct to the stage when, having grown more, they conduct perfectly. In other words, the neural mechanism for walking can function imperfectly before it can function perfectly. It takes several weeks of growth to pass from the barely functional condition to the fully functional condition; and it is during these weeks that the child seems to be learning to walk, while really his exercise of the partially developed neural mechanisms has no effect except to hasten their growth to some extent.
The fundamental sign or criterion of a native trait, in accordance with what we have been saying, is that it shall make its appearance when there has been no chance to acquire it through experience. This is the one perfect criterion; but unfortunately it cannot always be applied, especially with a slowly maturing and much-learning species such as the human. We need other criteria, and one of some value is the criterion ofuniversality.
Consider, for example, the attraction between the sexes, and ask whether this represents a native tendency, or whether each individual acquires it, as he does his "native language", by learning from his elders. Before the body reaches sexual maturity, there has been abundant opportunity for the quick-learning child to observe sex attraction in older people. Yet it is highly improbable that the liking for the other sex which he begins to show strongly in youth is simply an acquired taste. It is improbable because the attraction between the sexes is so universal not only among mankind but among birds and mammals and, indeed, practically throughout the animal kingdom.
Fighting is a similar case. Not so universal as the sex instinct, it still appears almost universally among birds and mammals.
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The human individual is an animal, and some of his native traits are universal among animals. He is a vertebrate, and some of his traits, though not present in all animals, are universal among vertebrates. He is a mammal, with mammalian traits; a primate, with primate traits; a man with human traits; a Chinaman or Indian or European with racial traits; belongs to a more or less definite stock or breed within the race, and possesses the traits that are common to members of that stock; and the same with family traits. The criterion of universality, in the light of these facts, comes down to this: thatwhen all individuals having the same descent show a trait in common, that trait is to be regarded as belonging to their native constitution--unless evidence can be brought forward to the contrary.
Smoking is universal among many Malay peoples, but we know, as a historical fact, that it was introduced among them after the discovery of America, not very many generations ago. Superstition is universal among some peoples, but we see the superstitious beliefs and practices taught by the older to the younger generation. Similarly with any specific language. It may very well be true in such cases that the universal practice appeals to some native tendency of the people; but the specific practice is handed down by tradition and not by inheritance.
Though the universality of a trait creates a certain presumption in favor of its being native, the opposite is not always true, for a trait may be native and yet appear in only a fraction of those who have a common descent. Eye color is certainly native, and yet one of two brothers may have blue eyes and the other brown. Mental deficiency runs in families, but usually some members of such families have{99}normal mentality. Genius is almost certainly a native trait, but it is the reverse of universal. The fact is that, along with certain traits that appear in all, the native constitution of a stock provides also for traits that appear only sporadically. Enough has been said to show that the criterion of universality is one that needs to be applied with judgment.
Acquired traits are on the whole much less universal, much more individual, than native traits. They are readjustments of the individual to environmental conditions; and, as the environment varies, so the adjustments vary, even when native traits are the same. Acquired traits are often specializations of the native traits, as any specific language is a specialization of the vocal utterances that are native and common to all men, and as the peculiar gait of an individual is a specialization of the universal walking movement. The gait differs with the environmental differences to which the individual has adapted himself, and will be different in one who has been accustomed to walk over rough ground and in one whose walking has been done on the city streets.
Acquired traits are not independent of native, but are developed on the basis of the native traits. They are acquired not by laying aside native tendencies and working out something entirely new, but by acting in accordance with the native tendencies and making such readjustments as the environment demands. The acquisition of mental traits is accomplished by the process oflearning, and we shall later have abundant occasion to examine it in more detail.
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For the present, let us simply take a brief survey of the mental field, and notice what types of reactions are native and what acquired. On the motor side, the reflexes are native, while habitual and skilled movements are acquired. On the sensory side, nature provides the use of the sense organs and the sensations immediately resulting from their stimulation. The baby responds to touch, warmth, cold, sound and light as soon as it is born, or practically so, and undoubtedly has the corresponding sensations. In other words, the rudiments of seeing, hearing, etc., are provided by nature. But when we say, "I see a dog" we mean more than that we are getting certain visual sensations; we mean that we see a known object or known sort of object. This implies recognition of the object, either as an individual thing or as one of a class; and this the baby can scarcely be supposed to do at first. He sees the dog to the extent that he responds by visual sensations to the light coming from the dog, but not to the extent that he recognizes the dog as a dog. In short, themeaningsof sensations are acquired, though the sensations themselves are native.
Things come to be known by use of the senses, and when thus known are not only recognized when present, but also remembered and thought of when they are not present to the senses. Such memories and items of knowledge, dependent as they are on experience, are to be reckoned among the acquired reactions. Ideas or conceptions of things also belong here.
Of the emotions, some are called "primary" or native--anger and fear are examples--while others result from the compounding of these primary emotions and are therefore acquired. As people and things come to be known, emotional reactions become attached to them, and give what{101}are often named "sentiments", such as love for this person, contempt for that one, family pride, patriotism. These sentiments, bound up as they are with knowledge and ideas, are certainly acquired.
Closely akin to the primary emotions are the native impulses, as the impulse to eat, to cry, to laugh, to escape from danger, to resist external compulsion and to overcome obstacles. The native impulses are the raw material out of which the numerous acquired desires of child and adult are formed. One sort of native impulse is the impulse to notice or pay attention to certain sorts of stimuli. These native interests of the child give birth to the various specialized interests of the adult. The baby's attention to a bright light represents a native interest; the older child's fixing his eyes on a dark brown piece of chocolate represents an acquired interest which has developed in a way that is easy to understand.
Finally, we must count among the native traits of the individual his inherited aptitudes for certain kinds of work. One child shows a natural aptitude for music, another for acting, another for mathematics, another for mechanical things, another for language, and so on. As any of these "natural gifts" is present in some degree in nearly all members of the human family, and not to anything like the same degree in animals, they are the characteristically human traits. It is on the basis of such native aptitudes that each individual proceeds, through the processes of learning, to build up his various acquired abilities, such as the ability to sing, to speak a certain language, to add, to work with tools, to perform athletic feats, and to take part in social activities of various sorts.
Our next task will be to examine more closely the native equipment of man, and after that to take up the process of learning, which is the way reactions are acquired. First the native, then the acquired. The acquired is based upon{102}the native. Acquired reactions are indeed so numerous that we cannot attempt even to list them all, let alone examine each one separately; but we can at least study thewayin which they are acquired. Native reactions are much less numerous, so that the student may hope to obtain a fairly comprehensive survey of this field, though, of course, without much detail.
The general plan of this book, then, is as follows. Up to this point, it has been providing a stock of methods and general conceptions to serve as tools in psychological study: consciousness and behavior, the introspective and objective methods, reactions and tendencies to reaction, native and acquired, and the part played by the nervous system. Next comes a survey of reactions provided by the native constitution, and after that a study of the process of learning or acquiring reactions. Finally, there are several chapters devoted to such topics as imagination, reasoning and will, which are ways in which the individual utilizes his whole equipment, native and acquired, in meeting the exigencies of life.
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1. Outline the chapter.2. When does the individual come into existence as an individual? When does he begin to acquire traits? How long does he continue to unfold his native traits, and how long does he continue to acquire traits?3. Which of the following elements of spoken language are native, and which acquired?
(a) Production of voice by the vocal cords and air blast from the lungs.(b) Varying the voice in loudness.(c) Varying the voice in pitch.(d) Production of vowels by different positions of the mouth.(e) Production of consonants by lip and tongue movements.(f) Combination of vowels and consonants into words.(g) Combination of words into idioms and grammatical sentences,(h) Attachment of meanings to words.(i) Sweet-toned voice.(j) Nasal twang.(k) Fluency in speaking.
4. In each of the following reactions, decide whether the connection of stimulus and response is probably native or acquired:
Edward L. Thorndike, in Chapter I of hisEducational 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 theirApplied Psychology, 1917, devote Chapters II and III to the matter of mental heredity.
Norsworthy and Whitley, in theirPsychology of Childhood, devote Chapters I and II to "original nature".
C. B. Davenport, in hisHeredity and Eugenics, presents evidence of the importance of heredity in determining mental and moral traits.
Yerkes and Bloomfleld, in a short article in thePsychological Bulletinfor 1910, Vol. 7, pp. 253-263, under the title, "Do Kittens Instinctively Kill Mice?", furnish a good illustration of the method employed in distinguishing native from acquired reactions.
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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 constitution.
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 coördination 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.
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 classes 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 coördinated 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 wasdelayedthat it began to look like an instinct, and it was because sneezing was aslowresponse 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.
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.
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, coöperates 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 arepreparatoryto the end-result, and inhibits others.
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 constitution 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.
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, horny 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 byteachinghim, 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 oflearningthat 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.
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 assume that all instinctive behavior has "survival value", value, that is, towards the survival of the individual or of the race. But this is an assumption, 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 asserting that these movements are of no use for survival, but at least their use is not obvious, and there is no reason for assuming 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.