The Encyclopedia Americana (1920)/Memory in Animals
MEMORY IN ANIMALS is to be studied in the light of comparative psychology, as between the human and the animal mind. To one class of thinkers this difference seems only one of degree; the mind of the animal to them is of the same nature as that of man, but is less developed by reason of limited experience, lack of stimulus because of comparatively small means of intercommunication of ideas, and general inferiority in complexity of brain structure. To another class of thinkers there is an essential difference — a permanent gulf between the menial processes and powers of brute and human beings. Memory is one of the most important attributes of mind and must vary with varying mental abilities. Thus it is hardly, if at all, perceivable in animals of low organization, but is more and more recognizable as we ascend the scale of animal organization, until at the top its operation is clearly visible. In studying it as regards animals we are met, however, with this initial and constant difficulty, that while we are able not only to question ourselves and report what we find for comparison with and discussion of the self-examination by other men, we cannot see into an animal's mind and must judge of its processes by their outward signs. Thus we may assure each other that we possess imagination, which is a high function of memory; but how are we to discover whether an animal indulges itself in such a mental exercise? When a horse goes slowly and with hanging head on an outward journey but becomes instantly animated and brisk in his gait when he is turned toward home, is that because he pictures in his mind the comfortable stable and good food awaiting him? If so, is that not an example of imagination? It has been customary to attribute all such acts as nest-building and the like to “instinct,” but innumerable examples of both faulty and beneficial work of this kind discourage faith in so simple a solution; and when a bee ingeniously stays a falling comb by a new brace or guy of wax, or a beaver overcomes a change in his pond by altering the direction of his dam or by building another in a new place, must these creatures not exercise imagination in order to plan and carry out the new way of meeting an unexpected difficulty? Each is applying his experience, recalled by memory, in the way he pictures (must picture) to himself the result of what he purposes to do, or he could not carry out his intention. That the animals we know best, horses, dogs, cats and so forth, have a very retentive memory, at least in certain directions, every one knows. The theory of many students of the matter is that this is purely “associative,” that something they see or smell or hear recalls a group of facts connected with it; and that it is impossible for them to recall this group without such a concrete suggestion. Much evidence may be produced throwing doubt on this limitation of their power.