An Introduction to Comparative Psychology

Chapter 12: Instinct and Intelligence

C. Lloyd Morgan

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I HAVE already described some of my experiments and observations on young chicks. I propose, in this chapter to call these and other similar observations to my aid in endeavouring to make clear the relation of instinct to intelligence.

The eggs from which in due course the chicks emerged, were taken from the hen two or three days before the time of hatching was fulfilled, and were placed in an incubator. The little birds, which were for the most part of good crossed breeds, with strains of Plymouth Rock, Dorking, and Game, had therefore no parental help in gaining some experience of the world. I first directed my attention to their powers of seizing and swallowing. Selecting one about eighteen hours old for definite experiment, I placed before him three small pieces of white of egg, moving them about a little in front of him with a. long pin to draw his attention to them. He soon pecked at one of these, and seized it at the fifth attempt, swallowing it a little awkwardly. The next he struck at the second attempt, but not fairly, so that it was thrust aside. Transferring his attention, therefore, to the third piece, he seized it and swallowed it at the third attempt. An hour later I tried him again with egg and crumb of bread. He generally struck the morsel at the second or third peck, though he sometimes failed to seize it. Once he seized and struck at the first attempt. The observations on this chick are, I think, typical. The pecking co-ordination in young chicks is fairly accurate, but by no means perfect,

(198) at birth. They generally strike a little short. If the birds are kept for a longer period in the drawer of the incubator before they are given food,-- and this may be done without injury to them, for they are hatched with a considerable store of food-yolk,-- the pecking is rather more accurate, but not quite accurate.

Towards the close of their first day of active life, I caused a small fly to walk across my experimental poultry-yard in front of the chicks. Most of, them took no notice; but one, whom I will call Blackie, followed and pecked at it. He caught it at the seventh attempt, and ate it; an hour later he caught another at the fourth peck, and subsequently a blue-bottle after twelve shots. This, however, he dropped and left uneaten. The others took no notice of flies, though they occasionally pecked at the disabled blue-bottle, without eating it. With a subsequent brood I tried throwing-in a large fly, from which a portion of the wings had been, of course painlessly, removed. This was on their second day. One followed it, but then stopped and gave the characteristic danger note-the first time I had heard it in the brood. Perhaps the buzzing noise made by the fly called forth this note of alarm. The same chick subsequently followed the fly, caught it after several pecks, and ate it.

These experiments and observations seem, therefore, to show that the skill in seizing is not perfect at birth, and that some practice is necessary. I have spoken so far only of morsels of food ; but I soon found that the chicks would peck at almost any small object I placed before them, and if small enough, almost anything was eaten, or at least tested in the bill -- grain, sand, crumbs, or little bits of a chopped up wax match. All the chicks pecked repeatedly at the letters, especially the large capitals, on the newspaper with which the experimental yard in my study was floored. I threw to my chicks about equal proportions of millet, canary seed, groats, and pari. They were about equally pecked at, and

(199) without apparent preference. The pari was too large for 'them, and the millet and canary were most eaten,-- probably because they were smaller and more easily swallowed. Sand and fine gravel were pecked up and swallowed quite as eagerly as grain. These are, of course, necessary to the bird for triturating the food in the gizzard. Gradually a preference for groats was established, and on the fourth day this kind of grain was generally selected from among the others. With regard to other objects, they -would peck at, but showed more discrimination as to swallowing, all sorts of things-pellets of paper, buttons, beads, bits of limestone, cigarette ash . They pecked at their own and their neighbours' toes repeatedly, each other's eyes occasionally, especially the eyes of the lighter-coloured birds, in which they were conspicuous ; the black-beaded head of a pin, the end of a match, the point of a pen-knife, a gold seal, my ring, and so forth. All were pecked at and examined, but the larger objects with some timidity. An ordinary Bryant & May wooden match, for example, was for a time too fearsome an object for any but Blackie to tackle. On the third day four of them pecked at a burning cigarette end more than once, but sometimes were stopped by a whiff of the smoke, and then shook their heads and wiped their bills in an exceedingly comical fashion. After a minute or two they went off, but returned occasionally. When the cigarette was burnt out and cold they came and looked at it, and in one case the chick, after looking but not pecking, wiped its bill.

I did not give them water till the morning of the second day, when they were from twenty to thirty hours old. I then placed a shallow tin of water among them. Of this they took no notice. Several happened to run through it, but still took no notice. Then one chanced, as he stood in it, to peck at his toes. He at once lifted his head in the characteristic way and drank repeatedly. The others still

(200) took no notice; but presently Blackie stood at the side and pecked at a bubble near the brim, and then he drank. It seemed as if the stimulus of water in the bill at once suggested the action of drinking. As he stood and drank, others came up and pecked at the troubled water, and then they too drank. I have already mentioned how one of the chicks was subsequently caused to stop and drink at the suggestion of running through the water.

I will here transcribe a page or two from my note-book descriptive of experiments and observations on young ducklings. After piping for some time within the egg, they were hatched respectively at 1 P.m. (a) and 5 P.m. (b).

On the next day, at 12 noon, I took them out of the incubator drawer and tried them with white of egg, The co-ordination for pecking was imperfect, and when a piece was seized it was mumbled rapidly and then shaken out of the bill unswallowed. They were both unsteady upon their legs, often tilting over backwards on to their tails, but a was decidedly the stronger. They both pecked with uncertain aim at anything which caught the eye, such as marks on the basket in which they had been placed for warmth, grain, sand, and so forth. I placed a shallow tin of water before them. They walked through it several times without taking any notice. I dipped a's beak into the water. It then drank with characteristic action, and pecking at the water drank again and again. Presently b imitated and drank repeatedly. Both pecked at white of egg held in forceps and seized at the third or fourth shot, shaking it Out of the bill; perhaps some was swallowed. I then placed them in the warm basket.

At 2.15 P.M. I took them out. They waddled about and came to the water. Both at once drank. They pecked at white of egg, placed on a black tray to make it more conspicuous, but shook most of it out of their bills. At 4 P.M. I put a in a bath. He floated and kicked vigorously and

(201) excitedly, dropping excrement. In less than a minute he swam round and pecked at the sides of the bath, I then took him back to my study. Both a and b shortly afterwards came directly to the tin of water and sat in it. They pecked without suggestion at pieces of white of egg on the tray, shaking their heads and mumbling it in the bill, but swallowing freely. They pecked at grain (pari), but shook it out without swallowing it. One of them scratched his head, and tumbled over in the process two or three times.

At 6.30 P.M. P.m. they ate white of egg freely, the pecking co-ordination being much more accurate but not quite accurate. I placed b in the bath. He too kicked excitedly and dropped excrement; but then swam about vigorously, pecking at the sides. The co-ordination for swimming is apparently much more perfect at birth than that for walking.

At 9 A.M.. next morning both a and b made at once for the water in their tin, drank, and sat in it. They ate keenly of white of egg, swallowing large morsels. Both occasionally scratched their heads, tumbling down each time. They smoothed the down of the breast after the manner in which every one has seen ducks make their toilet, applied their bills to the base of the tail, and rubbed their heads across and over their backs in the approved duck-fashion. They stood up and shook their wings, sitting down from imperfect co-ordination. At 11 A.M. I gave them, a winged fly, which a followed and pecked at several times, but failed to seize. It then got under the newspaper, and when I routed it out a again followed, pecking repeatedly, till it escaped through the netting round the yard. I placed it again within the duckling's reach, And lie caught it at the third peck, swallowing it apparently with much satisfaction. The other duck, b, caught a second fly after numerous abortive attempts. They pecked at and seemingly swallowed their own and chicks' droppings, and the signs of dislike were much less

(202) evident than with chicks. At 2 P.M, I tried them with a number of odd things, bits of paper, chopped-up matches, leaves, small flowers, small stones, red currants,-any thing of suitable size I could lay hands on. Each was seized and mumbled, and then either rejected or swallowed.

All this seems to show how necessary experience and the individual testing of things is both to young chicks and to young ducks. They have to find out for themselves the nature and value of everything they come across; but they learn rapidly and surely. They bring with them into the world an inherited aptitude for the performance of a number of activities which are essential to the maintenance of life ; but they do not seem to have any inherited acquaintance with the nature of anything. Mr Spalding, who many years ago made experiments with young birds, and obtained results in some respects different from those which I have obtained, describes the instinctive terror of young turkeys when they heard the cry of a hawk. I do not question the fact that their action betrayed fear, but I am disposed to question whether they were instinctively aware that the cry was that of a hawk. In any case my own chicks gave the characteristic danger churr, a most marked and 'peculiar note, at any loud, strange, and unusual sound, or on sight of an alarming object. It was not a little, amusing to see them, now standing and churring, and now scuttling away in terror, when I introduced to their notice a large Carabus beetle. Nothing, however, could be more marked than the definiteness of the effect of any very startling sound. The chicks either scatter and crouch down, remaining quite still for some seconds or even minutes, or crouch where they are and remain still. The perfect quiescence and stillness of such active and continually piping little birds is very remarkable, and clearly has a protective value. But this definite response follows on any disquieting sound or occurrence. If I threw a large piece of screwed-up paper

(203) among them, if I sneezed, or clapped my hands, or played a sharp chord on the violin, down they dropped; and I do not think they had any inherited acquaintance with violins. On the other hand when I took one of the chicks two days old to the cat, there was not the smallest sign of fear. The little bird took no notice of the cat. Nor did the cat take any notice of the bird, so long as I held it in my hand. When I placed it on the floor she seemed inclined to go for it; but the bird remained unaffected.

Even more remarkable was the complete indifference of my chicks to the clucking of a hen. I took two chicks ten days old in a basket to a poultry-yard. I opened the basket about two yards from a hen which was continually clucking to her brood. They took absolutely no notice of her. To test whether they were in a frightened condition, I offered them some grain on my hand. They jumped on my palm as usual, scratching it, and picking up grain. We put them with a hen in a small fowl-house. They did not seem much afraid of her, though she was terribly fussy; but the whole experience seemed to be novel to them, as indeed it was. A few days later, I took three more chicks to the poultry-yard. A hen was in the fowl-house with a Young brood, to which she Was repeatedly clucking-some grain having been thrown in to them. I put mine down outside -that is out of sight of her but within hearing of the clucking.. They took no notice whatever of the sound, but scratched about near me.

I will further illustrate their want of innate and inherited acquaintance with the things of this world by one or two more examples. I had fed them occasionally on small worms an inch or so in length. 1. then took similar sized pieces of worsted wool of a rich red-brown colour, and threw them among my chicks. The avidity with which they were seized was remarkable, and most exciting were the chases after the fortunate birdlin who had secured a

(204) worsted worm. I could not succeed in satisfying them with worsted, and eventually desisted lest my experiments should lead to serious indigestion. Some hours later I cut off a piece six inches long and threw it among them. Instantly there was the danger churr, and to a chick they feared to tackle that monstrous worm. Then I gave them a somewhat smaller piece, four inches long. This they regarded doubtfully; but one at length picked it up and ran off with it. There was much pulling of it one from another, but soon it was dropped. Occasionally it was picked up again and run off with, but eventually it was left unnoticed. The pleasures of eating worsted began to pall. I threw in small pieces, but they excited little interest; one was run off with and soon dropped, but eventually eaten. Two others were allowed to remain untouched. I left the four-inch piece. Presently I was roused from my writing by sounds of excitement and little pattering feet. Blackie had seized the piece, and was being chased for the prize. Escaping from the "yard," in which the chicks were confined, by leaping over the fender, he ran to the corner of my study, and after some struggles with the worsted succeeded in swallowing all the four inches.

It may be said that to supply worm-like worsted was a piece of base and unnatural deception. I will give one more case in which there was no such deception. I was desirous of ascertaining whether my chicks had any innate awareness of the difference between a large fly and a hivebee. Now Blackie was intimately acquainted with flies, large and small, and liked them well. When I placed a hive-bee in my experimental poultry-yard most of the chicks were afraid of it, as indeed they were of large flies but Blackie without hesitation snapped it up and ran off with it; then he dropped it, shook his head much, and wiped his bill repeatedly. As I mentioned before, I do not think he had been stung; if so, he quickly got over any ill effects,

(205) and was happy and eager about other things in a few minutes; more probably he had tasted the poison. In any case he no longer took any interest in that bee. Some hours later on the same day (his fifth) I placed beneath a glass tumbler a large fly and a small humble-bee, both winged. Blackie and another chick pecked at both, seen through the glass. I then let the bee escape; Blackie snapped it up, ran off with it and soon swallowed it. Another small humble-bee he seized at once, disabled it by dashing it against the ground with his bill, and swallowed it. Both of these humble-bees had stings. I threw a humble-bee among another brood of chicks ten days old. They pecked at it with rapid strokes, jerking it on one side. At this stage of development they approach anything new and strange to them with some suspicion, and peck at it in this way. For example I gave them some stewed currants and raspberries; these were struck at rapidly, and thrown aside. Presently one was picked up and run off with, other chicks giving chase, and eaten. A few currants were subsequently eaten, but with a good deal of shaking of the head, and apparently not much relish. The ducks ate them rather more freely. One of the ducks picked up the disabled humble-bee, and after mumbling it for some time in the water swallowed it.

I could generally in their early days induce my chicks. to take anything, and even to seize again something they had found distasteful, by tapping with my finger or a pencil on the ground to direct their attention to it, in imitation of the pecking of a hen. In this way, I induced one of my chicks to take up the beelike Eristalis which it had so far avoided. Directly he had seized it, others gave chase, and one took it from him and swallowed it. Next day I threw in among them a hive-bee and an emigrates. Both 'were left untouched. I drew their attention now to one, and now to the other, by tapping near, and moving it with my pencil;

(206) but without effect. I may say that tapping was ceasing to be effectual, as I had in this way frequently indicated things which they had not always found pleasant.

I have generally dismissed my chicks to the poultry-yard at the age of ten days, and in no case have kept them beyond three weeks. But I have never seen any chick, nor any duckling, catch a fly on the wing. There are often a good many flies hovering over, and settling in the experimental yard. I have very frequently seen the chicks, and occasionally the ducklings, strike at the flies in the air, but never successfully. I have experimented by placing flies in a tumbler covered with a card. The chicks then peck repeatedly at the flies. On removing the card, the flies escaped, and the chicks have pecked at them as they flew, but have not caught them. I also inverted a tumbler over flies, and removed the tumbler when they were on the ground. Blackie on one occasion caught one before it flew; but neither he nor any other of my chicks has been successful in catching a fly on the wing.

I have now described, perhaps in undue detail, a few of my observations as noted down at the time. To some they may seem trivial, and scarcely worth the making and the noting. To us, as students of comparative psychology, their interest lies in the light they throw on the beginnings of psychical life and activity in the chick or duck. Let us .now see how the observations serve to bring out the relation of instinct to intelligence. But first, What is instinct ? How shall we define or describe it? Let us go back to the little chick in its early efforts at pecking. Here we have a motor response to a certain stimulus. And there can be very little question that the motor response is, as we are apt to say, purely mechanical, -- or, as we should more correctly say, purely organic. It is a bit of animal automatism, not necessarily involving more than the lower brain-centres. But it is a bit of automatism which is accompanied by

(207) consciousness in the broader sense in which I have used this word. And the role of consciousness in the matter of pecking is to select the adequate responses, and to steady the muscular mechanism to its work. Let us describe the automatic activity as due to innate capacity for motor response.

Then in the animal kingdom, we find that the automatic responses which are the outcome of this innate capacity are variable in their adequacy. The chicks at first made bad shots as well as occasional good shots. Now the greater the variability, and the greater the initial percentage of inadequacy, the more necessity is there for the acquisition of skill by the individual. On the I other hand, the less the variability, and the smaller the initial percentage of inadequate response, the less the necessity for any individual acquisition of skill.

And now we can give a good working definition of instinct in its objective aspect, and at the same time indicate the relation of intelligence to instinct. Instinctive activities, in their theoretical perfection, are those in which there is no variability, in which the percentage of inadequacy is nil, and in which, therefore, there is no necessity for the individual acquisition of skill through the control and guidance of intelligence. If the chicks had pecked perfectly from the first they would have had this instinct in perfection. As it was, they required a little intelligence, acting by and through experience, to perfect their activities. The instincts were very nearly, but not quite, perfect.

A qualification may here be introduced. It is possible that, in the absence of intelligent control, the repetition of the activity would render it more accurate. In other words, the inaccuracy may have been partly due to a want of organic smoothness of working in the automatic mechanism. There can be no question that many activities, which are in due time,.performed in virtue of the automatic mechanism for response, are not and cannot be performed at birth, because

(208) the organic development is not then sufficiently advanced. The flight of birds is, according to Mr Spalding's observations, instinctive. He kept young swallows caged until they were fully fledged, and then allowed them to escape. They flew straight off at the first attempt. They exhibited the instinctive power of flight in a practically perfect form. But it is clear that such a proceeding would have been absolutely impossible for the callow young when they were first hatched. The instinctive power is in these and like cases deferred until such time as the organic development renders the automatic performance of the activities physically and physiologically possible. The automatic activities, which are the outcome of completed sexual development, are good examples of such deferred instincts.

It is a necessary corollary of the view here advanced that in instinct as such consciousness is a mere epiphenomenon -a by-product, with no bearing whatever on the performance of the activity in so far as it is instinctive. An organismif such exists-in which all the activities are throughout life purely automatic and purely instinctive, might indeed be conscious, but its consciousness would be of no practical value ; for all the activities being, ex hypothesi, automatic, there would be no conscious guidance or control. Consciousness might be present as a spectator of the activities ; but it would be a mere spectator without power of guidance, since, in so far as guided by intelligence, activities cease to be instinctive. It should be clearly grasped that, in so far as an activity is guided by individual control towards more complete accuracy, just so far does it cease to be instinctive, as the word is here used, and become intelligent. And when an instinct is, as so often is the case, modified and adapted to meet new circumstances, the modification and adaptation is no part of the instinct as such, but is due to intelligent control.

I repeat, then, that in instinct as such consciousness is an

(209) epiphenomenon or adjunct. But this does not, of course, imply that it is absent. Only in so far as consciousness accompanies the performance of instinctive activities can intelligence get a hold on them for the purpose of control and guidance. The performance of automatic activities affords to consciousness data, which form a foundation upon which the psychical structure reared by intelligence is based.

So far as vertebrates are concerned it is only in the lower forms of life, and in those which are born in a relatively advanced state of development, that we find the products off what I have termed the innate capacity for motor response in their relatively perfect and, so to speak, crystallized form as instincts. When little alligators just hatched, and still adhering to the shells by their umbilical cords, briskly show fight when approached, dragging their shell behind them and rushing with open jaws at any thing presented to them and madly biting it ;[1] or when little snakes taken prematurely from the mother's oviduct threaten to strike, and make the characteristic burring noise with the tail, [2] -- these are instances of unquestionable instinct. In young chicks the following responses are from the first sufficiently welldefined to be regarded as instinctive. Pecking, walking, scratching themselves, preening their down and feathers, stretching up and clapping their wings, scratching on the ground, squatting down and " dusting" themselves, scattering and crouching when alarmed, making the danger churr and other sounds previously described. In addition to these there are numerous- minor activities which are distinctly chick-like, ind differentiate the chicks from young ducklings. In the ducks, the way they seize and mumble the food in the bill, their swimming, their piping, their mode of smooth-

(210)-ing the down of the breast with their bills, applying the bill to the oil-gland, rubbing their heads across their backs, and other minor characters, are definite enough to be termed instinctive. But when we come to higher animals, especially those born in an immature condition and dependent at first upon parental care, it is not so easy to say what activities are definitely instinctive. The basis in innate capacity for motor response is unquestionable; but imitation and individual. guidance, through intelligent adaptation, are factors which render the activities less purely instinctive. I am inclined to regard imitation and tradition, especially in animals which live in flocks, packs, or herds, as of very great importance. By tradition I mean this : that the animal is born into a group of animals which perform a number of activities in certain ways, and that through the imitative tendency it falls into these ways, which are thus handed on or carried down through tradition. In a very interesting chapter on " Fear in birds," Mr W. H. Hudson, in his work on " The Naturalist in La Plata," describes many observations which point to the conclusion that the fear of man and other enemies is very largely due to parental instruction or to individual experience. And my own observations tend in the same direction. Mr Hudson uses the term " tradition" in the sense I have above adopted.

In any case I am quite clear that we must not be too ready to put down to instinct all the habits of animals, even definite habits common to a species, without taking the trouble to ascertain by careful observation and experiment how far these habits, though based on an innate capacity for motor response, are rendered definite. through imitation, parental teaching, or tradition.[3] I believe that there is here

(211) an, extensive field open to experimental observation. Is it too much to hope that in connection with some university in Great Britain there will some day be founded a Chair of Comparative Psychology, with an experimental station attached, where animals may be reared under test conditions and under foster-parents, so that the development of their intelligence may be carefully studied ?

No doubt in those species of which the normal environ- ment is relatively simple, and but little subject to variation, the responses due to inheritance will be relatively definite and instinctive in their nature. With increased complexity and variability of environment will come decreased definition in the inherited modes of response, such definition being left to individual acquisition. In man, therefore, with his exceedingly complex and variable environment, the number of definitely instinctive activities is few ; while at the same time the innate capacity for motor response forms a broad and ample, if relatively undifferentiated, foundation for an indefinite number of activities, which owe their guidance to the fostering care of parents and nurses.

Omitting now, for the present, any further reference to imitation, tradition, or parental guidance, and fixing our attention on the relation of instinct to intelligence, we may say that animals and men alike come into the world with an innate capacity for active response to certain stimuli. This

(212) is part of their organic inheritance. The response, may -be from the first an accurate and adequate response: in such cases we term it instinctive. But more frequently the responses have a variable amount of inaccuracy and inadequacy ; in such cases the animal, as a matter of observed fact, has a power of selective control over the responses; and this power of selective control over the activities which are essential to daily life, is the first stage of intelligence. And whereas for the instinctive action, as such, consciousness is only an epiphenomenon or adjunct accompanying the performance of the action, for its intelligent guidance consciousness is essential.

When the chick, so soon as it is taken out of the drawer of the incubator, strikes with fair but not complete accuracy at a piece of white of egg, there can be little question that this action-complex as it is, and involving as it does the, due co-ordination of a great number of muscular impulses-, is of the nature of an inherited organic response to stimulus that the sight of the small white morsel is just the touch of the trigger that, so to speak, fires off this complicated train of activities, the ability to perform which is innate. But we have every reason to suppose that the performance of these actions is accompanied by feeling or consciousness. So that in these early days of life the consciousness of the chick is, if one may say so, entering into and taking possession of its organic inheritance. And consciousness, like a wise heir,-, at once proceeds to set its estate in order and to remedy such imperfections as it -finds therein. In the case of the chick, the inheritance is already so well organized that it requires very little individual control of consciousness to put things in excellent working trim. In the case of the human infant, however, there are noteworthy differences. In the first place, the heir comes into possession when he is, ascompared with the chick, far younger and less mature; in the second place, his inheritance is of vastly greater extent,

(213) with commercial relations of far greater range and complexity ; and, in the third- place, it has been the custom for generations of his ancestors that during his minority he should be aided in the administration of his estate by Ifaithful stewards, and should be instructed therein by wise tutors. Still, notwithstanding these differences, it remains true that the infant consciousness, like the chick consciousness, has more gradually, no doubt, and with more external aid-to enter into and take possession of its organic inheritance; and, no matter how much he is aided and instructed, he has to do so individually and for himself. None can .share this task with him, or perform it for him. With this inheritance, moreover, he must make the best of life. No kindly uncle or aunt can bequeath him a new estate. The inheritance is his to deal with as he may and can, within the assigned limits; for his very power of dealing with the inheritance is part of the inheritance itself .

We are getting, however, too far from our foundations, and must return to the stage up to which we have, I trust, securely built. The chick., or the child, in the early hours or days of life acquires skill in the management of that part ..of the organic inheritance which we call its bodily organs. And this skill, rapidly in the chick, slowly in the child, reaches a high pitch of delicacy and exactitude. The chick .of a week old will pick a fly off your finger, and not so much as touch the finger itself. But this accuracy is the result of trial and error. What we term the control over our activities is gained in and through the conscious reinforcement of those modes of response which are successful, and the inhibition of those modes of response which are unsuccessful. The. successful response is repeated because of the satisfaction it gives ; the unsuccessful response fails to give satisfaction, and is not repeated. Sufficient has, however, been said in the chapter on the sense-experience of animals concerning the role of consciousness in the acquisition of

(214) skill. It is a vitally important matter in the psychology of animals, and involves the selective activity of intelligence. But we need not here repeat what has been already discussed on previous pages.

Let us pass, therefore, to another aspect of intelligent guidance, and in order to avoid referring back to instances before given in this chapter, let me further describe some observations on the young chicks, mention of which was made in a previous chapter. On the evening of their third day of active life, I placed before my little birds two objects new to their experience, a small worm and a yellow and black caterpillar-that of the cinnabar moth, so common in the summer on ragwort. The birds looked a little timidly and suspiciously at both of them. So far as I could judge, they were not more suspicious of one than of the other; they were probably suspicious of both, because the objects were rather larger than those which the chicks had been accustomed to peck at, and because they moved, They pecked at them timidly once or twice; but as it was getting late, and my chicks were rather sleepy, I felt it my duty, as their acting foster-mother, to put them to bed. Next morning, when they were fresh and vigorous, I repeated the experiment. Again both objects, the worm and the cinnabar caterpillar, were pecked at timidly, and eventually taken up in the bill and run off with. But the caterpillar, which is known to be distasteful to most- birds, was dropped at once; while the worm was, after some comical efforts,' bolted. Subsequently the caterpillar was occasionally pecked at, and more frequently merely looked at; but soon it was left, unnoticed. Fresh small worms, on the other hand, were at once and with confidence snapped up and carried off, causing a most exciting chase, the fortunate possessor being allowed no peace for the delightful efforts necessary for swallowing the worm. I have, with other chicks, tried similar experiments with cinnabar caterpillars and loopers,

(215) or other edible caterpillars of about the same size, and with similar results. And with ducklings the results are again similar. In no case, I may mention, was the. caterpillar injured or the skin broken.

In these experiments and observations the points to be noticed are, first, the absence of any instinctive acquaintance with the difference between a nice worm and a nasty caterpillar; secondly, rapid profiting by experience after a few practical trials ; thirdly, arising out of this, the discriminating by sight between the two objects; fourthly, the association of a nasty taste, or perhaps a disagreeable odour, with one of the objects, and pleasant gustatory results with the other; and, fifthly, guidance of subsequent action in accordance with the results of experience. In the last two points we have, in an elementary form, the basis of intelligent adaptation to circumstances. Intelligence, as I use the word in this work, is founded on experience; it involves the association of impressions and ideas, and it implies a power of control over the motor responses.

Let us now take a case illustrative of a rather more advanced stage of intelligence. I kept the chicks in my study, near a small gas-stove, so that I might regulate the temperature. For my first brood I made a sort of yard, paved with newspaper, and with newspaper walls propped against the fender, rugs, and so forth. (I now use wire netting.) At one side the turned-up newspaper rested against a chair. Blackie was a week old, and particularly bright and fresh, perhaps in consequence of his hearty meal of worsted. He was standing near the edge of the yard, pecking vigorously and persistently -it something, which I discovered to be the number of the page of the newspaper. He then transferred his attention -and his efforts to the somewhat turned-in corner of the newspaper, which was just ,-within his reach. Seizing this, he pulled at it, bending the newspaper down, and thus making a breach in the wall of

(216) my yard. Through this breach he stepped out into the wider world of my study. I put the paper back as before, caught the errant Blackie, and placed him in the yard, near the scene of his former efforts. He again pecked at the corner of the paper, again pulled it down, and again escaped. I then put him back as far as possible from this weak place in my poultry-yard. Presently, after some three or four minutes, he sauntered round to the corner, repeated his previous procedure, and again made his escape.

Unquestionably this is a more complex case of intelligence than the one I gave before. But it is of the same order. It was founded on experience; it involved the association of impressions and ideas; and it implied a power of profiting by the experience through the association. The chick found that a certain action, performed in the first instance, it would seem, without any view to any particular result, produced certain effects those effects were pleasurable; an association was formed between the idea of pecking at that corner and the idea of walking out into the room. And, subsequently, the action of pulling down the newspaper was repeated for precisely the same reason that the action of picking up the worm was repeated-namely, because it had become associated through experience with pleasurable consequences.

In Animal Behaviour I have described the results of further observations on young birds; but they serve only to reinforce the conclusions above drawn. As before ,noticed, Dr Stout would interpret the action of Blackie in pulling down the newspaper in terms of "meaning." Instead of saying that an association was formed between the Idea of pecking A that corner of the newspaper and the idea of walking out, he would say that through association pecking at that corner meant escape. This more synthetic mode of statement is preferable to that which seems to give to the several ideas free and independent existence.


  1. As observed by Mr Devenish. See Nature, v. 47, . 587.
  2. As observed by Mr W. Larden in the "Vivora de la Cruz.". See Nature, v. 42, p.115
  3. The complex problem of the migration of birds is a case in point. It is unquestionably one that involves more than instinct, though it has an instinctive basis. What is the nature of the internal craving which prompts to migration probably no one but the bird knows-and the bird only feels, but knows not. Nor do we know what the stimuli are which start the motor activities. in the far simpler case of the migration of recently-hatched eels (elvers) up the streams from the estuaries, the continued stimulus of flowing water may be the determinant of the continued upward and onward progress. I have before suggested that highly developed and differentiated sensations, through the constant use (by the individual) of the membranous labyrinth and semicircular canals, may be a factor in the direction of migration. But in any case there it probably a traditional element of great importance, the tradition having perhaps continued unbroken from a time when the configuration of land and sea differed from that which now obtains.

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