IT

CHAPTER V.

ASSOCIATION OF IDEAS IN ANIMALS.

T 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

shall in this work use the word quite broadly and generally, so as to comprise both consciousness in the more restricted sense 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 the 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, that 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 that 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 through 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

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 its 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 notunnatural tendency begotten by our 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

taste. And when we see that in the chick an association is 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

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 eat 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 he 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