An Introduction to Social Psychology
Chapter 2: The Nature of Instincts and Their Place in the Constitution of the Human Mind
William McDougall
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THE human mind has certain innate or inherited tendencies which are the essential springs or motive powers of all thought and action, whether individual or collective, and are the bases from which the character and will of individuals and of nations are gradually developed under the guidance of the intellectual faculties. These primary innate tendencies have different relative strengths in the native constitutions of the individuals of different races, and they are favoured or checked in very different degrees by the very different social circumstances of men in different stages of culture ; but they are probably common to the men of every race and of every age. If this view, that human nature has everywhere and at all times this common native foundation, can be established, it will afford a much-needed basis for speculation on the history of the development of human societies and human institutions. For so long as it is possible to assume, as has often been done, that these innate tendencies of the
(21) human mind have varied greatly from age to age and from race to race, all such speculation is founded on quicksand and we cannot hope to reach views of a reasonable degree of certainty.
The evidence that the native basis of the human mind, constituted by the sum of these innate tendencies, has this stable unchanging character is afforded by comparative psychology. For we find, not only that these tendencies, in stronger or weaker degree, are present in men of all races now living on the earth, but that we may find all of them, or at least the germs of them, in most of the higher animals. Hence there can be little doubt that they played the same essential part in the minds of the primitive human stock, or stocks, and in the pre-human ancestors that bridged the great gap in the evolutionary series between man and the animal world.
These all-important and relatively unchanging tendencies, which form the basis of human character and will, are of two main classes—
(I) The specific tendencies or instincts ;
(2) The general or non-specific tendencies arising out of the constitution of mind and the nature of mental process in general, when mind and mental process attain a certain degree of complexity in the course of evolution.
In the present and seven following chapters I pro-pose to define the more important of these specific and general tendencies, and to sketch very briefly the way in which they become systematised in the course of character-formation; and in the second section of this volume some attempt will be made to illustrate the special importance of each one for the social life of man.
Contemporary writers of all classes make frequent use of the words "instinct" and "instinctive," but, with very few exceptions, they use them so loosely that they have
(22) almost spoilt them for scientific purposes. On the one hand, the adjective "instinctive" is commonly applied to every human action that is performed without deliberate reflexion ; on the other hand, the actions of animals are popularly attributed to instinct, and in this connexion instinct is vaguely conceived as a mysterious faculty, utterly different in nature from any human faculty, which Providence has given to the brutes because the higher faculty of reason has been denied them. Hundreds of passages might be quoted from contemporary authors, even some of considerable philosophical culture, to illustrate how these two words are used with a minimum of meaning, generally with the effect of disguising from the writer the obscurity and incoherence of his thought. The following examples will serve to illustrate at once this abuse and the hopeless laxity with which even cultured authors habitually make use of psychological terms. One philosophical writer on social topics tells us that the power of the State "is dependent on the instinct of subordination, which is the outcome of the desire of the people, more or less distinctly conceived, for certain social ends" : another asserts that ancestor-worship has survived amongst the Western peoples as a "mere tradition and instinct": a medical writer has recently asserted that if a drunkard is fed on fruit he will "become instinctively a teetotaler": a political writer tells us that "the Russian people is rapidly acquiring a political instinct": from a recent treatise on morals by a distinguished philosopher two passages, fair samples of a large number, may be taken; one describes the "notion that blood demands blood" as an "inveterate instinct of primitive humanity"; the other affirms that "punishment originates in the instinct of vengeance" : another of our most distinguished philosophers asserts that "popular
(23) instinct maintains" that "there is a theory and a justification of social coercion latent in the term `self-government.'" As our last illustration we may take the following passage from an avowedly psychological article in a recent number of the Spectator: "The instinct of contradiction, like the instinct of acquiescence, is inborn. ... These instincts are very deep-rooted and absolutely incorrigible, either from within or from without. Both springing as they do from a radical defect, from a want of original independence, they affect the whole mind and character. "These are favourable examples of current usage, and they justify the statement that these words "instinct" and "instinctive" are commonly used as a cloak for ignorance when a writer attempts to explain any individual or collective action that he fails, or has not tried, to understand. Yet there can be no understanding of the development of individual character or of individual and collective conduct unless the nature of instinct and its scope and function in the human mind are clearly and firmly grasped.
It would be difficult to find any adequate mention of instincts in treatises on human psychology written be-fore the middle of last century. But the work of Dar-win and of Herbert Spencer has lifted to some extent the veil of mystery from the instincts of animals, and has made the problem of the relation of instinct to human intelligence and conduct one of the most widely discussed in recent years.
Among professed psychologists there is now fair agreement as to the usage of the terms "instinct" and "instinctive." By the great majority they are used only to denote certain innate specific tendencies of the mind that are common to all members of any one species, racial characters that have been slowly evolved in the process
( 24) of adaptation of species to their environment and that can be neither eradicated from the mental constitution of which they are innate elements nor acquired by individuals in the course of their lifetime. A few writers, of whom Professor Wundt is the most prominent, apply the terms to the very strongly fixed, acquired habits of action that are more commonly and properly described as secondarily automatic actions, as well as to the innate specific tendencies. The former usage seems in every way preferable and is adopted in these pages.
But, even among those psychologists who use the terms in this stricter sense, there are still great differences of opinion as to the place of instinct in the human mind. All agree that man has been evolved from pre-human ancestors whose lives were dominated by instincts; but some hold that, as man's intelligence and reasoning powers developed, his instincts atrophied, until now in civilised man instincts persist only as troublesome vestiges of his pre-human state, vestiges that are comparable to the vermiform appendix and which, like the latter, might with advantage be removed by the surgeon's knife, if that were at all possible. Others assign them a more prominent place in the constitution of the human mind; for they see that intelligence, as it increased with the evolution of the higher animals and of man, did not supplant and so lead to the atrophy of the instincts, but rather controlled and modified their operation ; and some, like G. H. Schneider[1] and William James,[2] maintain that man has at least as many instincts as any of the animals, and assign them a leading part in the determination of human conduct and mental process. This last view is now rapidly gaining ground; and this volume, I hope,
( 25) may contribute in some slight degree to promote the recognition of the full scope and function of the human Instincts; for this recognition will, I feel sure, appear to those who come after us as the most important advance made by psychology in our time.
Instinctive actions are displayed in their purest form by animals not very high in the scale of intelligence. In the higher vertebrate animals few instinctive modes of behaviour remain purely instinctive—i.e., unmodified by intelligence and by habits acquired under the guidance of intelligence or by imitation. And even the human infant, whose intelligence remains but little developed for so many months after birth, performs few purely instinctive actions ; because in the human being the instincts, although innate, are, with few exceptions, undeveloped in the first months of life, and only ripen, Or become capable of functioning, at various periods throughout the years from infancy to puberty.
Insect life affords perhaps the most striking examples of purely instinctive action. There are many instances Of insects that invariably lay their eggs in the only places where the grubs, when hatched, will find the food they need and can eat, or where the larvę will be able to attach themselves as parasites to some host in a way that is necessary to their survival. In such cases it is clear that the behaviour of the parent is determined by the impressions made on its senses by the appropriate objects or places: e.g., the smell of decaying flesh leads the carrion-fly to deposit its eggs upon it ; the sight or odour of some particular flower leads another to lay its eggs among the ovules of the flower, which serve as food to the grubs. Others go through more elaborate trains of action, as when the mason-wasp lays its eggs in a mud-nest, fills up the space with caterpillars, which it
(26) paralyses by means of well-directed stings, and seals it up; so that the caterpillars remain as a supply of fresh animal food for the young which the parent will never see and of whose needs it can have no knowledge or idea.
Among the lower vertebrate animals also instinctive actions, hardly at all modified by intelligent control, are common. The young chick runs to his mother in response to a call of peculiar quality and nestles beneath her; the young squirrel brought up in lonely captivity, when nuts are given him for the first time, opens and eats some and buries others with all the movements characteristic of his species; the kitten in the presence of a dog or a mouse assumes the characteristic feline attitudes and behaves as all his fellows of countless generations have behaved. Even so intelligent an animal as the domesticated dog behaves on some occasions in a purely instinctive fashion; when, for example, a terrier comes across the trail of a rabbit, his hunting instinct is immediately aroused by the scent; he becomes blind and deaf to all other impressions as he follows the trail, and then, when he sights his quarry, breaks out into the yapping which is peculiar to occasions of this kind. His wild ancestors hunted in packs, and, under those conditions, the characteristic bark emitted on sighting the quarry served to bring his fellows to his aid; but when the domesticated terrier hunts alone, his excited yap-ping can but facilitate the escape of his quarry; yet the old social instinct operates too powerfully to be con-trolled by his moderate intelligence.
These few instances of purely instinctive behaviour illustrate clearly its nature. In the typical case some sense-impression, or combination of sense-impressions, excites some perfectly definite behaviour, some movement or train of movements which is the same in all in-
( 27) -dividuals of the species and on all similar occasions; and in general the behaviour so occasioned is of a kind either to promote the welfare of the individual animal or of the community to which he belongs, or to secure the perpetuation of the species.[3]
In treating of the instincts of animals, writers have usually described them as innate tendencies to certain kinds of action, and Herbert Spencer's widely accepted definition of instinctive action as compound reflex action takes account only of the behaviour or movements to which instincts give rise. But instincts are more than innate tendencies or dispositions to certain kinds of movement. There is every reason to believe that even the most purely instinctive action is the outcome of a distinctly mental process, one which is incapable of being described in purely mechanical terms, because it is a psycho-physical process, involving psychical as well as physical changes, and one which, like every other mental process, has, and can only be fully described in terms Of, the three aspects of all mental process—the cognitive, the affective, and the conative aspects ; that is to say, every instance of instinctive behaviour involves a knowing of some thing or object, a feeling in regard to it, and a striving towards or away from that object.
We cannot, of course, directly observe the threefold psychical aspect of the psycho-physical process that issues in instinctive behaviour; but we are amply justified in assuming that it invariably accompanies the process
( 28) in the nervous system of which the instinctive movements are the immediate results, a process which, being initiated on stimulation of some sense organ by the physical impressions received from the object, travels up the sensory nerves, traverses the brain, and descends as an orderly or co-ordinated stream of nervous impulses along efferent nerves to the appropriate groups of muscles and other executive organs. We are justified in assuming the cognitive aspect of the psychical process, because the nervous excitation seems to traverse those parts of the brain whose excitement involves the production of sensations or changes in the sensory content of consciousness; we are justified in assuming the affective aspect of the psychical process, because the creature exhibits unmistakable symptoms of feeling and emotional excitement; and, especially, we are justified in assuming the conative aspect of the psychical process, because all instinctive behaviour exhibits that unique mark of mental process, a persistent striving towards the natural end of the process. That is to say, the process, unlike any merely mechanical process, is not to be arrested by any sufficient mechanical obstacle, but is rather intensified by any such obstacle and only comes to an end either when its appropriate goal is achieved, or when some stronger incompatible tendency is excited, or when the creature is exhausted by its persistent efforts.
Now, the psycho-physical process that issues in an instinctive action is initiated by a sense-impression which, usually, is but one of many sense-impressions received at the same time; and the fact that this one impression plays an altogether dominant part in determining the animal's behaviour shows that its effects are peculiarly favoured, that the nervous system is peculiarly fitted to receive and to respond to just that kind of impression.
( 29) The impression must be supposed to excite, not merely detailed changes in the animal's field of sensation, but a sensation or complex of sensations that has significance or meaning for the animal; hence we must regard the instinctive process in its cognitive aspect as distinctly of the nature of perception, however rudimentary. In the animals most nearly allied to ourselves we can, in many instances of instinctive behaviour, clearly recognise the symptoms of some particular kind of emotion such as fear, anger, or tender feeling; and the same symptoms always accompany any one kind of instinctive behaviour, as when the cat assumes the defensive attitude, the dog resents the intrusion of a strange dog, or the hen tenderly gathers her brood beneath her wings. We seem justified in believing that each kind of instinctive behaviour is always attended by some such emotional excitement, however faint, which in each case is specific or peculiar to that kind of behaviour. Analogy with our own experience justifies us, also, in assuming that the persistent striving towards its end, which characterises mental process and distinguishes instinctive behaviour most clearly from mere reflex action, implies some such mode of experience as we call conative, the kind of experience which in its more developed forms is properly called desire or aversion, but which, in the blind form in which we sometimes have it and which is its usual form among the animals, is a mere impulse, or craving, or uneasy sense of want. Further, we seem justified in believing that the continued obstruction of instinctive striving is always accompanied by painful feeling, its successful progress towards its end by pleasurable feeling, and the achievement of its end by a pleasurable sense of satisfaction.
An instinctive action, then, must not be regarded as
(30) simple or compound reflex action if by reflex action we mean, as is usually meant, a movement caused by a sense-stimulus and resulting from a sequence of merely physical processes in some nervous arc. Nevertheless, just as a reflex action implies the presence in the nervous system of the reflex nervous arc, so the instinctive action also implies some enduring nervous basis whose organisation is inherited, an innate or inherited psycho-physical disposition, which, anatomically regarded, probably has the form of a compound system of sensori-motor arcs.
We may, then, define an instinct as an inherited or innate psycho-physical disposition which determines its possessor to perceive, and to pay attention to, objects of a certain class, to experience an emotional excitement of a particular quality upon perceiving such an object, and to act in regard to it in a particular manner, or, at least, to experience an impulse to such action.
It must further be noted that some instincts remain inexcitable except during the prevalence of some temporary bodily state, such as hunger. In these cases we must suppose that the bodily process or state deter-mines the stimulation of sense-organs within the body, and that nervous currents ascending from these to the psycho-physical disposition maintain it in an excitable condition.[4]
( 31)
The behaviour of some of the lower animals seems to be almost completely determined throughout their lives by instincts modified but very little by experience ; they perceive, feel, and act in a perfectly definite and in-Variable manner whenever a given instinct is excited—i e., whenever the presence of the appropriate object coin-
(32) -cides with the appropriate organic state of the creature. The highest degree of complexity of mental process attained by such creatures is a struggle between two opposed instinctive tendencies simultaneously excited. Such behaviour is relatively easy to understand in the light of the conception of instincts as innate psycho-physical dispositions.
While it is doubtful whether the behaviour of any animal is wholly determined by instincts quite unmodified by experience, it is clear that all the higher animals learn in various and often considerable degrees to adapt their instinctive actions to peculiar circumstances ; and in the long course of the development of each human mind, immensely greater complications of the instinctive processes are brought about, complications so great that they have obscured until recent years the essential likeness of the instinctive processes in men and animals. These complications of instinctive processes are of four principal kinds, which we may distinguish as follows :—
(33)
(I) The instinctive reactions become capable of being Initiated, not only by the perception of objects or the kind which directly excite the innate disposition, the natural or native excitants of the instinct, but also by ideas of such objects, and by perceptions and by ideas of objects of other kinds:
(2) the bodily movements in which the instinct finds expression may be modified and complicated to an in-definitely great degree :
(3) owing to the complexity of the ideas which can bring the human instincts into play, it frequently hap-pens that several instincts are simultaneously excited ; when the several processes blend with various degrees of intimacy:
(4.) the instinctive tendencies become more or less systematically organised about certain objects or ideas.
The full consideration of the first two modes of complication of instinctive behaviour would lead us too far into the psychology of the intellectual processes, to which most of the textbooks of psychology are mainly devoted. It must suffice merely to indicate in the present chapter a few points of prime importance in this connection. The third and fourth complications will be dealt with at greater length in the following chapters, for they stand in much need of elucidation.
In order to understand these complications of instinctive behaviour we must submit the conception of an instinct to a more minute analysis. It was said above that every instinctive process has the three aspects of all mental process, the cognitive, the affective, and the conative. Now, the innate psycho-physical disposition, which is an instinct, may be regarded as consisting of three corresponding parts, an afferent, a central, and a motor or efferent part, whose activities are the cognitive,
( 34) the affective, and the conative features respectively of the total instinctive process. The afferent or receptive part of the total disposition is some organised group of nervous elements or neurones that is specially adapted to receive and to elaborate the impulses initiated in the sense-organ by the native object of the instinct; its constitution and activities determine the sensory content of the psycho-physical process. From the afferent part the excitement spreads over to the central part of the disposition; the constitution of this part determines in the main the distribution of the nervous impulses, especially of the impulses that descend to modify the working of the visceral organs, the heart, lungs, blood-vessels, glands, and so forth, in the manner required for the most effective execution of the instinctive action; the nervous activities of this central part are the correlates of the affective or emotional aspect or feature of the total psychical process.[5] The excitement of the efferent or motor part reaches it by way of the central part; its constitution determines the distribution of impulses to the muscles of the skeletal system by which the instinctive action is effected, and its nervous activities are the correlates of the conative element of the psychical process, of the felt impulse to action.
Now, the afferent or receptive part and the efferent or motor part are capable of being greatly modified, in-dependently of one another and of the central part, in the course of the lift history of the individual; while the central part persists throughout life as the essential un-
( 35) changing nucleus of the disposition. Hence in man, whose intelligence and adaptability are so great, the afferent and efferent parts of each instinctive disposition are liable to many modifications, while the central part alone remains unmodified : that is to say, the cognitive processes through which any instinctive process may be initiated exhibit a great complication and variety ; and the actual bodily movements by which the instinctive process achieves its end may be complicated to an indefinitely great extent ; while the emotional excitement, with the accompanying nervous activities of the central part of the disposition, is the only part of the total instinctive process that retains its specific character and remains common to all individuals and all situations in which the instinct is excited. It is for this reason that authors have commonly treated of the instinctive actions of animals on the one hand, and of the emotions of men on the other hand, as distinct types of mental process, failing to see that each kind of emotional excitement is always an indication of, and the most constant feature of, some instinctive process.
Let us now consider very briefly the principal ways in which the instinctive disposition may be modified on its afferent or receptive side; and let us take, for the sake of clearness of exposition, the case of a particular instinct, namely the instinct of fear or flight, which is one of the strongest and most widely distributed instincts throughout the animal kingdom. In man and in most animals this instinct is capable of being excited by any sudden loud' noise, independently of all experience of danger or harm associated with such noises. We must suppose, then, that the afferent inlet, or one of the afferent inlets, of this innate disposition consists in a system of auditory neurones connected by sensory nerves
(36) with the ear. This afferent inlet to this innate disposition is but little specialised, since it may be excited by any loud noise. One change it may undergo through experience is specialisation; on repeated experience of noises of certain kinds that are never accompanied or followed by hurtful effects, most creatures will learn to neglect them[6] ; their instinct of flight is no longer excited by them ; they learn, that is to say, to discriminate between these and other noises; this implies that the perceptual disposition, the afferent inlet of the instinct, has become further specialised.
More important is the other principal mode in which the instinct may be modified on its afferent or cognitive side. Consider the case of the birds on an uninhabited island, which show no fear of men on their first appearance on the island. The absence of fear at the sight of man implies, not that the birds have no instinct of fear, but that the instinct has no afferent inlet specialised for the reception of the retinal impression made by the human form. But the men employ themselves in shooting, and very soon the sight of a man excites the instinct of fear in the birds, and they take to flight at his approach. How are we to interpret this change of instinctive behaviour brought about by experience? Shall we say that the birds observe on one occasion, or on several or many occasions, that on the approach of a man one of their number falls to the ground, uttering cries of pain; that they infer that the man has wounded it, and that he may wound and hurt them, and that he is therefore to be avoided in the future? No psychologist would now accept this anthropomorphic
( 37) interpretation of the facts. If the behaviour we are considering were that of savage men, or even of a community of philosophers and logicians, such an account would err in ascribing the change of behaviour to a purely intellectual process. Shall we, then, say that the sudden loud sound of the gun excites the instinct of fear, and that, because the perception of this sound is constantly accompanied by the visual perception of the human form, the idea of the latter becomes associated with the idea of the sound, so that thereafter the sight of a man reproduces the idea of the sound of the gun, and hence leads to the excitement of the instinct by way of its innately organised afferent inlet, the system of auditory neurones? This would be much nearer the truth than the former account; some such interpretation of facts of this order has been offered by many psychologists and very generally accepted.[7] Its acceptance involves the attribution of free ideas, of the power of representation of objects independently of sense-presentation, to whatever animals display this kind of modification of instinctive behaviour by experience—that is to say, to all the animals save the lowest ; and there are good reasons for believing that only man and the higher animals have this power. We are therefore driven to look for a still simpler interpretation of the facts, and such a one is not far to seek. We may suppose that, since the visual presentation of the human form repeatedly accompanies the excitement of the instinct of fear by the sound of the gun, it acquires the power of exciting directly the reactions characteristic of this instinct, rather than indirectly by way of the
(38) reproduction of the idea of the sound; i.e., we may sup-pose that, after repetition of the experience, the sight of a man directly excites the instinctive process in its affective and conative aspects only ; or we may say, in physiological terms, that the visual disposition concerned in the elaboration of the retinal impression of the human form becomes directly connected or associated with the central and efferent parts of the instinctive disposition, which thus acquires, through the repetition of this experience, a new afferent inlet through which it may henceforth be excited independently of its innate afferent inlet.
There is, I think, good reason to believe that this third interpretation is much nearer the truth than the other two considered above. In the first place, the assumption of such relative independence of the afferent part of an instinctive disposition as is implied by this interpretation is justified by the fact that many instincts may be excited by very different objects affecting different senses, prior to all experience of such objects. The instinct of fear is the most notable in this respect, for in many animals it may be excited by certain special impressions of sight, of smell, and of hearing, as well as by all loud noises (perhaps also by any painful sense-impression), all of which impressions evoke the emotional expressions and the bodily movements characteristic of the instinct. Hence, we may infer that such an instinct has several innately organised afferent inlets, through each of which its central and efferent parts may be excited without its other afferent inlets being involved in the excitement.
But the best evidence in favour of the third interpretation is that which we may obtain by introspective observation of our own emotional states. Through
( 39) injuries received we may learn to fear, or to be angered by, the presence of a person or animal or thing towards which we were at first indifferent ; and we may then experience the emotional excitement and the impulse to the appropriate movements of flight or aggression, without recalling the nature and occasion of the injuries we have formerly suffered; i.e., although the idea of the former injury may be reproduced by the perception, or by the idea, of the person, animal, or thing from which it was received, yet the reproduction of this idea is not an essential step in the process of re-excitement of the instinctive reaction in its affective and conative aspects; for the visual impression made by the person or thing leads directly to the excitement of the central and efferent parts of the innate disposition. In this way our emotional and conative tendencies become directly associated by experience with many objects to which we are natively indifferent ; and not only do we not necessarily recall the experience through which the association was set up, but in many such cases we cannot do so by any effort of recollection.[8]
Such acquisition of new perceptual inlets by instinctive dispositions, in accordance with the principle of association in virtue of temporal contiguity, seems to occur abundantly among all the higher animals and to be the principal mode in which they profit by experience and learn to adapt their behaviour to a greater variety of the objects of their environment than is provided for by
( 40) their purely innate dispositions. In man it occurs still more abundantly, and in his case the further complication ensues that each sense-presentation that thus becomes capable of arousing some emotional and conative disposition may be represented, or reproduced in idea; and, since the representation, having in the main the same neural basis as the sense-presentation, induces equally well the same emotional and conative excitement, and since it may be brought to mind by any one of the intellectual processes, ranging from simple associative reproduction to the most subtle processes of judgment and inference, the ways in which any one instinctive disposition of a developed human mind may be excited are in-definitely various.
There is a second principal mode in which objects other than the native objects of an instinct may lead to the excitement of its central and efferent parts. This is similar to the mode of reproduction of ideas known as the reproduction by similars ; a thing, or sense-impression, more or less like the specific excitant of an instinct, but really of a different class, excites the instinct in virtue of those features in which it resembles the specific object. As a very simple instance of this, we may take the case of a horse shying at an old coat left lying by the roadside. The shying is, no doubt, due to the excitement of an instinct whose function is to secure a quick retreat from any crouching beast of prey, and the coat sufficiently resembles such a crouching form to excite the instinct. This example illustrates the operation of this principle in the crudest fashion. In the human mind it works in a much more subtle and wide-reaching fashion. Very delicate resemblances of form and relation between two objects may suffice to render one of them capable of exciting the emotion
( 41) and the impulse which are the appropriate instinctive response to the presentation of the other object; and, in order that this shall occur, it is not necessary that the individual shall become explicitly aware of ,the resemblance between the two objects, nor even that the idea of the second object shall be brought to his consciousness; though this, no doubt, occurs in many cases. The wide scope of this principle in the human mind is due, not merely to the subtler operation of resemblances, but also to the fact that through the working of the principle of temporal contiguity, discussed on the foregoing page, the number of objects capable of directly exciting any instinct becomes very considerable, and each such object then serves as a basis for the operation of the principle of resemblance; that is to say, each object that in virtue of temporal contiguity acquires the power of exciting the central and efferent parts of an instinct renders possible the production of the same effect by a number of objects more or less resembling it. The conjoint operation of the two principles may be illustrated by a simple ex-ample : a child is terrified upon one occasion by the violent behaviour of a man of a peculiar cast of countenance or of some special fashion of dress; thereafter not only does the perception or idea of this man excite fear, but any man resembling him in face or costume may do so without the idea of the original occasion of fear, or of the terrifying individual, recurring to consciousness.
As regards the modification of the bodily movements by means of which an instinctive mental process achieves,[9] or strives to achieve, its end, man excels the animals even to a greater degree than as regards the modification of the cognitive part of the process. For
(42) the animals acquire and use hardly any movement-complexes that are not natively given in their instinctive dispositions and in the reflex co-ordinations of their spinal cords. This is true of even so intelligent an animal as the domestic dog. Many of the higher animals may by long training be taught to acquire a few movement-complexes—a dog to walk on its hind legs, or a cat to sit up ; but the wonder with which we gaze at a circus-horse standing on a tub, or at a dog dancing on hind legs, shows how strictly limited to the natively given combinations of movements all the animals normally are.
In the human being, on the other hand, a few only of the simpler instincts that ripen soon after birth are displayed in movements determined purely by the innate dispositions; such are the instincts of sucking, of wailing, of crawling, of winking and shrinking before a coming blow. Most of the human instincts ripen at relatively late periods in the course of individual development, when considerable power of intelligent control and imitation of movement has been acquired ; hence the motor tendencies of these instincts are seldom manifested in their purely native forms, but are from the first modified, controlled, and suppressed in various degrees. This is the case more especially with the large movements of trunk and limbs ; while the subsidiary movements, those which Darwin called serviceable associated movements, such as those due to contractions of the facial muscles, are less habitually controlled, save by men of certain races and countries among whom control of facial movement is prescribed by custom. An illustration may indi-
(43) -cate the main principle involved : One may have learnt to suppress more or less completely the bodily movements in which the excitement of the instinct of pugnacity naturally finds vent ; or by a study of pugilism one may have learnt to render these movements more finely adapted to secure the end of the instinct; or one may have learnt to replace them by the habitual use of weapons, so that the hand flies to the sword-hilt or to the hip-pocket, instead of being raised to strike, whenever this instinct is excited. But one exercises but little, if any, control over the violent beating of the heart, the flushing of the face, the deepened respiration, and the general redistribution of blood-supply and nervous tension which constitute the visceral expression of the excitement of this instinct and which are determined by the constitution of its central affective part. Hence in the human adult, while this instinct may be excited by objects and situations that are not provided for in the innate disposition, and may express itself in bodily movements which also are not natively determined, or may fail to find expression in any such movements owing to strong volitional control, its unmodified central part will produce visceral changes, with the accompanying emotional state of consciousness, in accordance with its un-modified native constitution ; and these visceral changes will usually be accompanied by the innately determined facial expression in however slight a degree; hence result the characteristic expressions or symptoms of the emotion of anger which, as regards their main features, are common to all men of all times and all races.
All the principal instincts of man are liable to similar modifications of their afferent and motor parts, while their central parts remain unchanged and determine the
( 44) emotional tone of consciousness and the visceral changes characteristic of the excitement of the instinct.
It must be added that the conative aspect of the psychical process always retains the unique quality of an impulse to activity, even though the instinctive activity has been modified by habitual control; and this felt impulse, when it becomes conscious of its end, assumes the character of an explicit desire or aversion.
Are, then, these instinctive impulses the only motive powers of the human mind to thought and action? What of pleasure and pain, which by so many of the older psychologists were held to be the only motives of human activity, the only objects or sources of desire and aversion?
In answer to the former question, it must be said that in the developed human mind there are springs of action of another class, namely, acquired habits of thought and action. An acquired mode of activity becomes by repetition habitual, and the more frequently it is repeated the more powerful becomes the habit as a source of impulse or motive power. Few habits can equal in this respect the principal instincts; and habits are in a sense derived from, and secondary to, instincts; for, in the absence of instincts, no thought and no action could ever be achieved or repeated, and so no habits of thought or action could be formed. Habits are formed only in the service of the instincts.
The answer to the second question is that pleasure and pain are not in themselves springs of action, but at the most of undirected movements ; they serve rather to modify instinctive processes, pleasure tending to sustain and prolong any mode of action, pain to cut it short; under their prompting and guidance are effected those modifications and adaptations of the instinctive bodily
( 45) movements which we have briefly considered above.[10]
We may say, then, that directly or indirectly the instincts are the prime movers of all human activity; by the conative or impulsive force of some instinct (or of some habit derived from an instinct), every train of thought, however cold and passionless it may seem, is borne along towards its end, and every bodily activity is initiated and sustained. The instinctive impulses determine the ends of all activities and supply the driving power by which all mental activities are sustained ; and all the complex intellectual apparatus of the most highly developed mind is but a means towards these ends, is but the instrument by which these impulses seek their satisfactions, while pleasure and pain do but serve to guide them in their choice of the means.
Take away these instinctive dispositions with their powerful impulses, and the organism would become in-capable of activity of any kind; it would lie inert and motionless like a wonderful clockwork whose main-spring had been removed or a steam-engine whose fires had been drawn. These impulses are the mental forces
( 46) that maintain and shape all the life of individuals and societies, and in them we are confronted with the central mystery of life and mind and will.
The following chapters, I hope, will render clearer, and will give some support to, the views briefly and somewhat dogmatically stated in the present chapter.[11]
