The Conception of the Animal Mind

It is only in the vertebrates that plastic behaviour steps gradu ally into the foreground, although the lower groups of vertebrates are little in advance of the highest invertebrates. Since memory replaces intellect in the animal, we frequently find quite amazing instances of memory, particularly in relation to the sense of lo cality and of finding the way home. It is remarkable that the types of animal which exhibit a complex faculty of association and capacity for learning from experiences composed of numerous details, are phylogenetically young forms which developed only a little before the Chalk age. These are the social insects, dragon flies, robber-flies, birds, and higher mammals. But the faculty of association is not in itself sufficient to build up higher psychic functions by the summation of simpler psychic elements. The so-called psychology of association, which held the field for some time, came to grief in the attempt to maintain this view. The capacity for highly complex performances and in the end for single-purposed actions depends upon the fact that the method of trial and error, which is exhibited by most animals as a test ing of various reaction possibilities, is now moved up into the brain, where it intervenes in the various physiological processes due to experience.

Reflexes and Consciousness.

We have seen that reflexes are the basis of most animal movements. It is therefore natural to enquire into the relationship of reflex movements to psychic hap penings and all the more so since in man there can be a con nection between reflexes and the phenomena of consciousness. There is a whole series of reflexes which take place without our being conscious of them. Thus the pupil of the eye enlarges or con tracts according to the intensity of the light falling on the retina quite without our knowledge. Nor are we able to alter the size of the pupil aperture at will. In other cases at least the end result is known and often the stimulus also. If one sits with one leg crossed over the other and hanging down loosely, a light tap with the edge of the palm on the front of the shin just beneath the knee-cap causes a jerking up of the leg. The movement and the touch-stimulus are felt. But we are not able to suppress or alter the course of this reflex by an effort of will. There are other reflexes which we can inhibit at will. Such are the closing of the eye-lids when the lashes are lightly touched or when an object comes rapidly towards the eye. Since in ourselves some reflex phenomena take place with, others without, consciousness, and some can be suppressed by the will, while others cannot be so influenced, we can draw no conclusions as to whether consciousness accompanies reflex behaviour seen in animals.

Even though many instinctive actions appear to be accomplished with conscious intention owing to their remarkable adaptiveness, yet we can often convince ourselves by appropriate experiments that the animal has no consciousness of the purposeful nature of its actions. When the conditions are so altered that the actions of

the animal are turned into nonsensical, non-adaptive ones, they still continue to run their course, which corresponds to an inborn plan. From this it becomes evident that the animal acts in reality merely by instinct, that is without knowledge of the object and meaning of its behaviour. We see that instinct is really only a concatenation of reflexes. The burying beetle, Necrophorus yes puilo, attracted by the smell of the corpse of a small animal, com monly buries the latter beneath the soil by undermining the ground. Then it lays its eggs in the corpse, thus providing for its brood when it hatches out. It has been observed that the animals are able to gain possession of a corpse, hung purposely on a small gibbet, by digging around the posts and so making it fall. H. Fabre had proved by a series of extremely ingenious experiments that this bringing down of the gibbet is in no way the result of a special cleverness on the part of the beetles, but that it happens by mere chance. For if the suspended corpse just touches the ground next to the posts of the gibbet, the beetles commence to dig there. As a result, the gibbet often falls down owing to a loosening of the soil. But if the spot at which the corpse touched the ground happened to be some little distance from the posts of the gibbet, the beetles never dug close to the posts. Hens in the open scrape at the ground in a purposeful manner to unearth worms, insects, and so forth. Yet the following experiment shows that they have no knowledge of the intention nor the meaning of their behaviour. A hen climbed into the earthenware plate in which grains of corn were brought to her and, once inside the plate, continued the scraping movements which were now com pletely purposeless. The only effect of the movements was that the corn flew out and was scattered. Next the hen was given her corn in a small box with sides i5cm. high, which was firmly fixed to the floor of the chicken-run. The hen walked up to the box, began to peck at the seeds inside it, and in so doing made power ful scraping movements on the bare wooden floor of the box, which movements were of course completely senseless. Such observa tions must warn us to examine very critically actions of animals which appear to us purposeful, and not to interpret them straight away in an anthropomorphic manner. If consciousness exists in the hen which behaves as we have observed, it is certainly quite another kind of consciousness than that which we should feel in the animal's position.