On this view, then, we may see in instinctive behaviour, and the multifarious automatic acts of animals, a means of providing experience of the right kind and on profitable lines. We may see in the play-instincts of the young a training ground for the more serious business of animal life—a theme developed by Professor Groos. We may see in the imitative tendency—the innate proclivity to follow a lead blindly and at first unintelligently—a further means of providing those useful items of experience which intelligence finds so serviceable. And we may see in the intelligence which can profit by chance occurrences that arise in these several ways all that suffices for the simple needs of animal existence.

With some differences of opinion Dr. Thorndike and I have much in common in the conclusions to which we have been independently led as to the method and limits of animal intelligence. We seem to be in essential agreement in the belief that the method of animal intelligence is to profit by chance experience without rational foresight, and that unless such experience be individually acquired, the data essential for intelligent progress are absent. While in our attempts to realize the general nature of animal consciousness there is a close similarity of treatment. In my “Introduction to Comparative Psychology” a good deal of space is devoted to an analysis of the psychology of skill “in order that we may infer what takes place in the minds of animals;” and I said:—“When I am playing a hard game of tennis, or when I am sailing a yacht close to the wind in a choppy sea, self does not at all tend to become focal. Hence, though I am a self-conscious being I am not always self-conscious. And presumably when I am least self-conscious, I am nearest the condition of the animal at the stage of mere sense experience. I am exhilarated with the sense of pleasurable existence, my whole being tingles with sentient life. I sense, or am aware of, my own life and consciousness, in an unusually subtle manner. Experience is vivid and continuous. Such I take it to be the condition of the conscious but not yet self-conscious animal.”

I can therefore cordially endorse Dr. Thorndike’s conclusions as expressed in the following passages:—

“One who has watched the life of a cat or dog for a month or more under test conditions, gets, or fancies he gets, a fairly definite idea of what the intellectual [intelligent] life of a cat or dog feels like. It is most like what we feel when consciousness contains little thought about anything, when we feel the sense-impressions in their first intention, so to speak, when we feel our own body, and the impulses we give to it. Sometimes one gets this animal consciousness while in swimming, for example. One feels the water, the sky, the birds above, but with no thoughts about them or memories of how they looked at other times, or æsthetic judgments about their beauty; one feels no ideas about what movements he will make, but feels himself make them, feels his body throughout. Self-consciousness dies away. Social consciousness dies away. The meanings, and values, and connections of things die away. One feels sense-impressions, has impulses, feels the movements he makes; that is all.”

And after an illustration from such a game as tennis, Dr. Thorndike adds: “Finally the elements of the associations are not isolated. No tennis-player’s stream of thought is filled with free-floating representations of any of the tens of thousands of sense-impressions or movements he has seen and made on the tennis-court. Yet there is consciousness enough at the time, keen consciousness of the sense-impressions, impulses, feelings of one’s bodily acts. So with the animals. There is consciousness enough, but of this kind.”

It may be said that between the method of intelligence and that of fully developed rational procedure there is a wide gap which must have been bridged in the course of mental evolution. Unquestionably. And in contending that the methods of the animal are predominantly intelligent, I am far from wishing to assert dogmatically that in no animals are there even the beginnings of a rational scheme. Indications thereof do not indeed at present appear to have been clearly disclosed by experiment. But the experimental development of the subject is still in its infancy. We shall probably have to await the further results which must be the outcome of patient and well-directed child-study. The human child does pass in the course of his individual development from intelligent to rational procedure. Here there is a bridge which is crossed by every child. When we know more about the stadia of this development we shall be in a position to apply the results obtained in child-study in the analogous field of animal-study. Till then we must possess our souls in patience, and base our provisional conclusions on the results of systematic investigation, rather than on those of casual observation and anecdote.

IV.—The Evolution of Intelligent Behaviour

No attempt can be made in this section to trace the successive stages of the evolutionary progress of intelligence from its lower to its higher developments. It is indeed questionable whether comparative psychology has, as yet, accumulated a sufficient body of data to render such a task profitable or even possible. And the lower the level of intelligence with which we have to deal, the less reliable are the scanty psychological data which we can obtain. To interpret the mental processes which accompany the acts of even the higher animals is a hard task, requiring careful psychological analysis. Still harder is the task to infer the psychological basis of the actions of the lower animals.

It is difficult to say where, in the hierarchy of animal progress, the beginnings of intelligence can first be traced. In the articulated animals, such as the insects, spiders, and crustacea, there is abundant evidence of intelligence of a relatively high grade. But even in their case, how hard it is to realize the nature of their experience—to get any adequate notion of their mental processes! We are inevitably forced to describe their psychology in the most general terms. So, too, with forms still lower in the scale of intelligence. Many molluscs unquestionably profit by experience. But can we clearly picture to ourselves the nature and manner of acquisition of this experience? The way in which limpets return to the scars on the rock which form their homes seems to show that they have acquired a practically adequate experience of their near surroundings. Romanes cites[65] some of the earlier observations which have been extended by Professor Ainsworth Davis.[66] I looked into the matter myself some years ago, at Mewps Bay near Lulworth in Dorsetshire. The method adopted[67] was to remove the limpets from the rock, and affix them at various distances from their scars. This can be done without difficulty or injury to the mollusc if one catches them as they are moving. But one must make sure that they are just leaving or returning to their proper homes, and are not taken in the midst of a more extended peregrination, as in that case their special scars cannot be noted. Failure to be careful in this matter vitiated my earlier observations, which are therefore excluded in the following table:—

Number removed.Distance in inches.Number returned.
In 2 tides.In 4 tides.Later.
25621——
2112135—
21181062
3624113