An Introduction to Comparative Psychology

Chapter 5: Association of Ideas in Animals

C. Lloyd Morgan

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IT can scarcely be doubted that for animals, as for man, there is a wave of consciousness. By animals I here mean vertebrates, to which, as I have before said, I propose to limit my attention in this Introduction to Comparative Psychology. In mammals and birds, and to a less degree in reptiles, amphibians, and fishes, there is a community of sensory endowment and a community of brain-structure. All these forms of life belong to one great branch of the animal kingdom ; and if we accept evolution as the true basis of explanation alike in biology and in psychology, we are justified in inferring that, co-ordinate and concurrent with the community of nervous mechanism and its physiological functioning, there is a community of psychical nature and psychological functioning.

When we watch a cat stealing upon a bird we may fairly conclude that the impression of the bird is focal to consciousness, and that the bird is set in a visual scene the surrounding details of which are merely marginal in the cat's consciousness, as are also the movements of her own limbs, which are being subconsciously controlled in accordance with the nature of the ground over which she is passing. Let us not quarrel over the word " consciousness." There are some who contend that in strict accuracy, that is to say, according to their definition of the word, we must distinguish between the consciousness of man and the consentience of animals. I do not propose to discuss the advisability or the reverse of such limitation of the term "consciousness," I

(85) in this work use the word quite broadly and generally, as to comprise both consciousness in the more restricted rise and consentience. I repeat that when the cat is stealing upon the bird we have good grounds for inferring that there are both focal and marginal elements in consciousness ; and hence that the state of consciousness at he moment in question might, were our means of acquiring the necessary knowledge less inadequate than they inevitably are, be represented in the form of a curve.

I shall take it for granted then, without further discussion, at in The animals we are considering there are, as in man, both focal and marginal elements in consciousness. The wave of consciousness may be in them far simpler in constitution than it is in man; but I shall adopt the hypothesis at there is such a wave, and shall use the terms " impression " and " idea " for the focal -constituents of the wave. Thus the kitten has an impression of the ball with which it is playing, and the hungry dog may have an idea of a nice meaty bone.

That the impression is brought to the focus by primary suggestion through afferent fibres, no one is likely to question. But that the idea is due to secondary suggestion rough association it may be well to illustrate, though it is scarcely probable that many would be disposed to doubt the fact.

I have made a series of observations on young chicks and ducks hatched out in an incubator, with the object of studying experimentally the establishment of associations. A few extracts from my note-book will suffice to show the nature of the evidence. A chick, about eighteen hours old, pecked at its own excrement rapidly thrice in succession, and then shook its head and wiped its bill on the ground. Ten minutes later it began to peck, but checked the action before reaching the excrement and wiped its bill. A little later it came near, looked at the material, and then walked

(86) away. A visual impression and a taste impression had become associated, and the recurrence of the former suggested a representation of the latter as an idea. On the morning of their second day of life I placed a shallow tin of water before my chicks. They took no notice, and several ran through it without heeding it. Presently one of the birds, while standing in the. water, chanced to peck at it toes, as chicks so frequently do. At once he lifted his head and drank repeatedly. Another was led to drink by pecking at a bubble on the brim. Others seemed to do so by imitation of their neighbours. Some time afterwards one chanced to run through the water. It at once stopped and drank. It seemed as if the wetting of the feet suggested the act of drinking-the two experiences having become associated by contiguity. One of my chicks three or four days old snapped up a hive-bee and ran off with it. Then he dropped it, shook his head much and often, and wiped his bill repeatedly. I do not think he had been stung, probably he tasted the poison. In any case, in a few minutes he seemed quite happy and eager after new experiences. But though he came and looked at it once or twice, he made no further attempt to run off with the hive-bee. An association, based on a single experience, was at least temporarily established. Similar experiments with the unpleasant caterpillar of the cinnabar moth and with lady-birds showed that the association between a peculiar appearance and nasty taste was in all cases very rapidly established, and that the visual impression suggested the idea or re-presentation of unpleasant gustatory experience.

A word of warning may here be introduced against a not unnatural tendency begotten by out living in what may be termed an atmosphere of human conceptions. We call the cinnabar caterpillar an " object," and we say that the object has a certain visual appearance, banded with gold and black, and also, for the chick which takes it into its bill, a certain

(87) taste. And when we see that in the chick an association established 'between appearance and taste, we are apt, without further thought, to suppose that the chick, two or three days old, distinguishes between the object, its appearance, and its taste, and associates the appearance of the object with its taste as distinguishable and already distinguished qualities. Now I shall have to say somewhat concerning " objects " and " qualities " in the proper place. Here at present we have nothing to do with them save resolutely to exclude them from our thought. The visual impression of the banded black and yellow caterpillar is a bit of simple and direct experience : the gustatory impression which follows is no less a bit of simple and direct experience. And when, subsequently,- the sight of the caterpillar suggests -its taste, what we have is the presentative occurrence of the one bit of experience suggesting the representative occurrence .of the other bit of experience. The little chick does not bother its head in the most rudimentary way about either objects or qualities. Sense-experience is all-sufficient for the practical needs of its simple life.

One of the greatest difficulties against which the student of zoological psychology has to contend is, that the language in which he needs must describe and endeavour to explain the mental processes of animals embodies the results of a vast amount of analytic thought. He has to employ phrases which imply analysis, to describe experiences which involve no analysis. We speak, for example, of the " taste of the caterpillar," which seems to imply the distinction between taste as a property of the caterpillar, and the caterpillar as possessed of this property. For those critics who delight to catch an author tripping in his words rather than in his thought, nothing would be easier than to score a point by exclaiming, "The very language the author employs betrays the fallacy of his contention ; he pretends to believe that animals are incapable of analysis ; and yet there is scarcely a phrase

(88) descriptive of the mental processes of animals which does not plainly indicate such power of analysis.'' I am desirous that the reader should quite clearly grasp (1) that our language is full of the results of the analysis of phenomena; (2) that this analysis has to be effected by man, the language maker and the language user; (3) that language, being thus saturated with the results of analysis, it is practically impossible to describe mental processes in their primitive unanalysed modes of occurrence without using phrases which are analytic in form ; and (4) that the use of such analytic phrases must not be taken to imply analysis in the animal. What we call the " taste of the caterpillar " is for the chick a bit of simple, direct, unanalysed, sensory experience.

To return now to my experimental poultry-yard. I have been much struck, as I watched the progress day by day of my families of chicks or ducklings, with the fact that although they bring with them into the world an inherited aptitude to perform certain activities, yet all experience, even of the performances of these activities, is a matter of individual acquisition. And further, that this experience is rendered of practical value through association. Only in so far as associations are formed does experience afford a basis for the guidance of action, and the conduct of the business of life. It is only as associations are established between impressions of sight and taste that the chick begins to learn what to cat and what to avoid. At first he picks up anything of convenient size that catches his observant eye. Every minute of the early hours and days of life lie is establishing associations of eminently practical value for his life's guidance The environment is simple, and the associations direct and oft-recurring. Hence at the end of a week or ten days he is a remarkably wide-awake little bird.

But although there is, so far as I have been able to observe, no satisfactory evidence of anything like inherited experience, the associations being in all cases individually

(89) acquired, I think it extremely probable that there are inherited facilities for association, if I may so phrase it. I mean that there very likely exist in the cerebral hemispheres nerve-tracks which facilitate the establishment of such associations as those between sight and taste. What is inherited, however, is the mechanism by which an association may be established; what is a matter of individual acquisition is the association that is established. My chicks thoroughly enjoyed the warmth of my hand, and when I stretched it out towards them they would run to it, and nestle in the half-closed palm. I instance this as an association which in this particular form could not have been inherited, and must have been of purely individual establishment.

I may here mention a somewhat amusing case of association in two of my ducklings. I had placed before them regularly at the same time each morning a black tray, on which was a shallow tin containing water; they ran to it, drinking eagerly, sitting in the tin and washing. On the sixth morning I gave them at the usual time the black tray and the shallow tin, but without the water. They ran to it, scooped with their bills along the bottom of the empty tin, and made all the motions of the beak characteristic of drinking. They sat in the empty tin, waggling their little tails and ducking their heads, throwing wholly imaginary water over their backs. This they continued to do for ten minutes, -- the action becoming less and less vigorous. Then I gave them water. - Next morning I repeated the same experiment. They ran to the tin, squatted in it, and tried to find water to drink; but after three minutes or so went off, but ran to it again when I poured in water. The following morning, after Just searching for water in the empty tin, they waddled off.

It must be remembered that the chicks and ducklings upon which my observations and experiments were carried out were entirely dependent upon their own individual efforts

(90) in gaining acquaintance with their little world; for they were hatched out in an incubator, and had never known a mother. Under more normal conditions they would have had some guidance from the ben as mother or as fosterparent, and they would have grown up among all the traditions of the poultry-yard. They would therefore have. had some guidance in the formation of associations,--imitation of the hen, and to a less degree of other individuals of their kind, aiding them not a little in the acquisition of experience. I was, however, unable to observe, when I returned my young birds to the yard whence I had -obtained the eggs,' that, at ages of from ten days to three weeks, they were in any marked respect inferior to other chicks of the same age. No doubt there were minor matters, in which their experience was deficient; but these were nowise obvious.

It would seem then difficult to overestimate the importance of the association of ideas in the early life of animals. It is the means-the sole means-by which experience. is made available for the guidance of action. Experience, no matter how often repeated, is useless for guidance unless associations are established. If a chick takes a ladybird in its beak forty times, and each time finds it nasty, this is of no practical value to the bird unless the sight of the insect suggests the nasty taste before the insect is taken into the bill. And it must be remembered that the utmost which parental care can effect is a certain amount of guidance in the establishment of associations. Association links cannot be formed vicariously. Hence no matter how complete and how long-continued the fosterage in the early days of life, all the associations must he established by the individual himself for his own individual guidance.

I have utilised my observations on young chicks to bring out this conclusion, because in them the establishment of.' association-links can be so readily watched. But analogous facts can be observed in all young animals. And it is of

(91) course those associations which are liable to reiterated reestablishment, when the linkage tends to fade, as it is apt to do in animals and men, that become so ingrained in experience.' as to be practically indissoluble. A merely chance association may last for a while but will fade more or less quickly. I was experimenting with a fox-terrier, and testing his intelligence in bringing a stick through railings,narrow gaps in a hedge, and so forth. He was keenly eager to fetch the stick when I threw it just the other side of a hedge. To reach the gap he had to pass through some nettles. By these he was stung, and dropping the stick ran off and rolled in the grass. I fetched the stick, called and patted the dog, and then threw the stick out into the open field. He rushed off; but when he saw the stick on the ground nothing would induce him to touch it. - I broke another stick, and 'he fetched it again and again. But whenever I threw that stick, he refused to pick it up even when coaxed to do so. A temporary association between that stick and the stinging had seemingly been established; but it was only temporary. I took him on for a five or six mile walk, and then returned, after a couple of hours or so, 'to the same field. I threw the stick; he bounded after it, and fetched it without hesitation. The smart of the nettle had subsided, and with it, seemingly, the association.

I may here give another example of association in the same dog. He will fetch sticks for me by the hour; but if I throw a golf-ball, or even a rounded stone, then sticks at once lose their interest. I may pocket the ball and throw sticks, but the most he will do is run a few yards after them, and then come and beg for the ball. I therefore tried the following experiment: -- I placed a ball in my pocket -- an old one that he had gnawed almost beyond recognition -- and started forth for my walk, repeatedly throwing a stick for him to his perfect satisfaction. I then put my hand in my pocket, fumbled the ball, and patted the dog's head

(92) with that hand. He sniffed at it eagerly. I threw a stick; he bounded off a few yards, and then came jumping at my side. A race after the ball had been suggested through the channel of olfactory sensations, but the stick no longer had the same interest.

I think it possible that association through olfactory channels may help us to account for the results of certain experiments I have made with dogs. The experiments themselves were suggested by that recorded by Mr Romanes, in an article entitled " Fetishism in Animals."[1] Soap-bubbles are blown, and the dogs induced to follow them. When the bubbles are touched by the dog with nose or paw, they burst. Now, in the great majority of cases the dog takes little or no notice of the bubbles, and when they burst shows very little sign of surprise, or any other emotion. The game is evidently regarded as a poor one. Sometimes, however, when the dog bursts the bubble with his nose, he shakes his head, and appears to experience discomfort. In only one case have I found anything like a marked effect. The dog retreated under the furniture, and could not be induced to approach the bubbles. If one bursts one of the bubbles with one's own nose, one finds the result a little curious,-one feels the bursting, and there is a sudden concentrated flooding of the nose with a smell of soap. Such a gush of odoriferous particles may well disquiet an animal with so strong a sense of smell as the dog. I am indeed surprised that the majority of dogs take so little notice of this effect, though they sometimes do, as I have said, show signs of discomfort, I am disposed to think, however, that in the case of the dog which hid under the sofa there may have been association; for the dog hated being washed above all things, and would have to be dragged out of hiding when the time for the trying ordeal

(93) came. Of all smells few had for him more unpleasant associations than that of soap. This of course may have been a coincidence. And I have tried other dogs which hated being washed without observing any such marked effect. One Yorkshire terrier, 1 may mention, licked, the bubbles, and apparently liked this- new method of experimentation. Its mistress told me that the dog liked soap, and always licked itself all over after the bath. Mr Romanes's fetishistic interpretation of the very marked effects on his terrier, I am disposed to question. He tells me that the dog disliked being washed, and thinks that such an association as I suggest was not unlikely.

It would not be difficult to fill several pages with examples of association in animals; but it is better to leave the reader to draw upon his own experience for supplementary cases. If he has any close acquaintanceship with animals, he will have little difficulty in doing so. Of course it is only when the idea suggested through association expresses itself in action that we can obtain evidence of its existence. And much of the training we give to our domestic animals consists in establishing certain associations, such that a word, a sign, a touch of rein or whip, suggests infallibly the appropriate action. And every one who has had anything to do with the training of animals knows well how much they differ in the rapidity with which association - links are formed, and in their permanence when once they have been established.

Further evidence of the establishment of associations is given where the animal in some way indicates to its fellows or to man its emotional state, or its desire that some action should be performed. I find that the sounds emitted by young chicks are decidedly instinctive, -that is to say, they are inherited modes of giving expression to certain emotional states. And some of them are fairly differentiated. At least six may be distinguished.- First, the gentle piping

(94) sound expressive of contentment,-- for example, when one takes the little bird in one's hand. A further low note, a sort of double sound, seems to be associated with extreme pleasure, as when one strokes the chick's back. Very characteristic and distinct is the danger note. This is heard on the second or third day. If a large humble-bee, or a black beetle, or a big lump of sugar, or in fact anything largish and strange, be thrown to them this danger note is at once heard. Then there is the piping sound, expressive apparently of wanting something. It generally ceases when one goes near them and throws some grain, or even only stands near them. My chicks were accustomed to my presence in the room, and generally were restless, and continuously made this sound when I left them. Then there is the sharp squeak when one seizes a chick against its inclination. Lastly, there is the shrill cry of distress, when, for example, one of them is separated from the rest. I have very little doubt that all of these sounds have a suggestive value of emotional import for the other chicks. Certainly the danger note at once places others on the alert, and the pleasure note will cause others to come to the spot where the little bird is when the note is sounded. I mention these associations, because they are the best examples I know of anything of the nature of inherited associations, and I would specially draw attention to the fact that they are at first scarcely at all particularised. The sound is associated with an emotional state, not with any particular experience which gives rise to that state, and it probably suggests a similar. state not in any way particularised. It is possible that with the advent of particular experiences the sounds may be further differentiated; but I have not been able to obtain evidence of the fact. Somewhat will be said later on concerning the means of communication among animals; and the question how far such communication is suggestive of

(95) general emotional states, and how far of definite impressions or particular experiences, will be briefly considered.

Passing to higher animals, there is no question that they may be taught to signify to us by certain actions that they desire certain things to be done for them; and as this is evidence of particular associations, one or two instances may be adduced. One of my 'own cats would always touch the handle of the door when she wished it opened. We had established this association by building on an apparently chance occurrence, when the cat, reaching up, touched the handle. By always opening the door when she so reached up to the handle, And taking no notice when she merely sat and mewed, the suggestive value of the action became definitely fixed. Sir John Lubbock taught his intelligent black poodle Van to distinguish between plain and printed cards. The cards were about ten inches by three, and had some simple word such as FOOD or OUT printed on them in large letters. Van learnt not only to distinguish these from each other, but to associate particular words with particular experiences. When she wanted food or tea, she fetched the appropriate card and got what she wanted in exchange. In 113 cases, during twelve days, she only made two mistakes, one of which was bringing " door " instead of " food." In these cases she had twelve cards from which to select. These interesting experiments show differential associations involving considerable power of discrimination in sense-experience. To these cases I may add an observation which I have already given in my work on Animal Life and Intelligence. When I was at the Diocesan College near Capetown, a retriever, Scamp, used to come and sit with the lecturers at supper. He despised bread, but used to get an occasional bone, which he was not, however, allowed to eat in the hall. He took it to the door and stood there till it was opened for him. On one occasion he heard outside the excited barking of the other dogs. He ran

(96) round the hall, picked up a piece of bread which one of the boys had dropped, and stood with it in his mouth at the door. When it was opened, he dropped the bread and raced off into the darkness to join the other dogs.

Experiment and observation on our domesticated animals thus bring out abundant evidence of the association of ideas, and especially of new and unwonted associations. But it must be remembered that the whole natural life of animals affords a body of evidence which is only less striking because it is more familiar, and because we are so apt to suppose that the activities of animals are performed merely in accordance with their instinctive nature, forgetting to how large an extent this basis owes its differentiation to individual acquisition through experience. Amid more or less uniform surroundings, and under the influence of common habits of life, the individual experience is so far uniform -as to give rise to similar associations. But this does not alter the fact that for the individual these particular associations are a matter of individual acquisition.

There can be little question that in animal life the vast majority of associations are associations by contiguity. But it is worth inquiring whether among animals, as with man, there are also associations by similarity. We may, at any rate for the present, exclude associations by perceived similarity of relationship. These depend upon the perception of relations, and I propose to devote a chapter to the question whether animals are able to perceive relations as such. The question is therefore whether ideas are suggested to animals through association by resemblance. When my chicks hid learnt to avoid hive-bees, mainly I think through tasting or perhaps smelling the poison, I threw among them one or two of those flies, Eristalis, which bear a tolerably close superficial resemblance to the hive-bee. Not a chick would touch them, and the danger or warning note was frequently heard. Here was a clear case of avoidance

(97) through resemblance. But whether there was the suggestion of the idea of a hive-bee through resemblance is another, matter, and one we are hardly in a position to determine. The question is whether the sequence in the consciousness of the chick was (1) visual impression of eristalis, (2) visual idea of bee, (3) taste-idea of poison; or (1) visual impression of eristalis, (2) taste-idea of poison. In other words, did the chick, on seeing the eristalis, have an idea of a hive-bee and then a suggestion, of the nasty taste, or did the chick on seeing the eristalis have at once a suggestion of the taste? I think it far more probable that the chick simply mistook, as we say, the eristalis for a bee,-that, in fact, the impression of eristalis was nowise differentiated from previous impressions of hive-bees.

This case is typical of a whole range of biological phenomena which come under the head of mimicry. Mimicry involves resemblance; and in all cases the mimicking form (and it must be remembered that it is biological mimicry, not psychological : there is no possibility of intentional imitation) gains advantage from its resemblance to another form which is possessed of disagreeable or hurtful qualities. The resemblance also must be sufficient to suggest the hurtful quality as an idea of sense-experience. If the animal could differentiate the mimicking from the, mimicked form, all the advantage would at once be lost. Hence it is 'probable that there is in these cases no association by resemblance, but rather a perfect illusion, the mimicking and mimicked form giving rise to a single undifferentiated impression. And we may fairly regard the glaring colours of noxious insects a- specially developed, so as to be of strikingly suggestive value.

If then we conclude, as I think we must conclude, that cases of mimicry do not afford a trustworthy indication of association by resemblance, -we shall find it difficult to obtain evidence of a satisfactory kind of the existence of

(98) this mode of association in animals. Not that this necessarily shows that such associations by resemblance are absent from the mental processes of animals. It is quite possible, nay more, exceedingly probable, that they may frequently occur. And the difficulty we have in finding evidence of their existence is perhaps due to the fact that such associations have little or no practical utility.

Dr Stout, in his Manual of Psychology, well describes the role of association in the lower phases of mental development as affording opportunities for the acquirement of meaning He emphasizes the importance of the incorporation of new items of experience with those already acquired. In place of saying that, when a chick refrains from pecking at a nauseous cinnabar caterpillar, the visual impression suggests the idea or re-presentation of unpleasant -gustatory experience (supra, p. 86), he say: -- "The sight of the cinnabar caterpillar re-excites the total disposition left behind by the previous experience of pecking at it, seizing it, and ejecting it with disgust. Thus the effect of these experiences is revived. The sight of the cinnabar caterpillar has acquired a meaning. It means the experiences which in the first instance followed it ; and just because means them, it may more or less dispense with the necessity of actually repeating them." This synthetic conception of the re-excitement of the previous experience as a whole is distinctly more satisfactory than the more analytic statement given in the text above. It carries further -and puts more clearly what I bad in mind when I wrote the paragraph beginning near the foot of page 96.


  1. Nature, vol. xvii., p. 168.

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