ANIMAL PSYCHOLOGY. That depart ment of psychology (q.v.) which has for its sub ject matter the composition and functions of mind as it is found in animals below man. As regards its problem, one cannot question the propriety of the title; but as regards the methods which it employs, animal psychology has little in common with psychology proper. The special method of normal psychology is the method of introspection (q.v.). Modern psychology is a system of facts gleaned from the introspective reports of trained observers, working under the refinements of experimental conditions. In sharp contrast with this is the position of animal psy chology; for an investigator of the animal mind has no source of first-hand evidence. lhesults can be obtained only by a series of inferences. The data at our disposal are simply certain move ments executed by the animal. From these movements we must draw our eouclusion that such and such mental processes are present or absent, using the objective as index or criterion of the subjective.
It is clear that, under such circumstances, even the most conscientious observer is liable to error. And the most obvious fallacy is that of humanizing the animal, of reading our own mind into his actions, and so of endowing him with all the forms of mental experience that are familiar to ourselves. Wundt, commenting on this attitude, cites an instance from Bomanes's Animal Intelligence. "I have noticed," writes an English clergyman, "in one of my formicaria, a subterranean cemetery where I have seen some ants burying their dead by placing earth above them. One ant was evidently much affected, and tried to exhume the bodies: but the united exertions of the yellow sextons were more than sufficient to neutralize the effort of the discon solate mourner." "Ilow much." asks Wundt, "is fact, and how much imagination? It is a fact that ants carry out of their nest, deposit near by, and cover up dead bodies, just as they do any thing else that is in their way. They can then pass to and fro over them without hindrance. In the observed case they were evidently inter rupted in this occupation by another ant, and resisted its interference. The cemetery, the sex tons, the feelings of the disconsolate mourner, which impelled her to exhume the body of the departed—all this is a fiction of the sympathetic imagination of the observer."
Sometimes, however, the observer's attitude to the animal mind is precisely the reverse: there is extreme underestimation, in place of extreme overestimation. Descartes 15913 - 11150 the founder of modern philosophy, after sharply dis tinguishing between matter and mind, body and soul. asserts that man is a composite being, a combination of soul and body, but that the ani mals are mere automata, all their actions and movements taking place automatically. It is plain that there can lie no "animal psychology" for the Cartesians. There were, however, some among the earlier thinkers who did not deny consciousness to the lower creation. Aristotle, the "father of psychology," declared that animals exercise the functions of assimilation and repro duction, and possess a "faculty of feeling." to which is added in higher forms the capacity to retain sense-impressions, or memory. Man is distinguished from the animals by his endowment with the "faculty of knowledge" or "reason." But, at the best, animal psychology was never recognized as a worthy—o• even as a possible— line of special inquiry.
The work of Darwin is admittedly the root of our present interest in animal intelligence. From the point of view- of the theory of evolution, which regards not only the entire physical struc ture of the human body, including the nervous system, but also our entire mental structure. which stands in such intimate relation to the nervous system, as the result of a long period of development in the animal world, the close observation of the pre-human mind becomes a matter of the utmost importance. We always understand things better when we know how they have grown. Hence the psychologist has turned his attention to the problem of genesis. or the growth of mind. The problem may be attacked in two ways. We may trace the growth of mind in the individual: this is the application of the genetic method to child-study, and gives us child psychology (q.v.). Or, since man is but a highly developed animal. we may trace the growth of mind in the animal world: this is the application of the method to mind at large, and gives us comparative (or animal) psychol ogy.