ANIMAL PSYCHOLOGY. Definition. — That portion of the general science of psy chology which concerns itself especially with a study of mind in animals other than man is generally designated either as animal psychol ogy or as comparative psychology. Obviously, it would be more logical as well as scientifically more profitable to designate as animal psychol ogy the study of mind in animals as contrasted with the study of mind in plants. In this defi nition animals should be used as inclusive of man. In this article the popular usage has been accepted, and the discussion will treat of the psychology of infrahuman animals.
For many centuries, the human race has exhibited keen interest in the instincts, habits, experiences, and life-history of animals, as well as in their structures, bodily functions, and development. Animal psychology existed for Aristotle, who, at considerable pains and great expense, accumulated a vast and hetero geneous assemblage of facts concerning animal behavior. Modern science finds little of value in this ancient record, for the observations were uncritically made and carelessly recorded.
In the Middle Ages and later the animal soul became.a bone of contention, and men sought heatedly to prove or to disprove its existence. One camp gathered facts to prove that animals are purely instinctive mechanisms, endowed by the Creator with the necessary powers to meet life's demands, and lacking will, purpose, in sight and reasoning ability. The other camp quite assiduously, albeit not so religiously, mar shalled evidences that intelligence, even to thought and reasoning as 'well as instinct, is common to brute and man.
Not until the last century did inquiry into the nature of the animal mind become fruitful of relatively disinterested and reliable results. The work of Darwin, Wallace, and their con temporaries stirred an interest in the origin, development or natural history of things biolog ical, which shortly came to include mind. In fact, Darwin himself clearly indicated the pos sibility of learning much concerning the evolu tion of mind in animals and its growth in individuals.
In the latter half of the 19th century, especially from 1860 on, the science of animal psychology was born and vigorously advanced. England and the continent shared in this scien tific achievement; but to the former belongs the credit of having produced a small group of gifted and devoted students of animal behavior.
Romanes, Lubbock, and Morgan did more to create a valuable body of knowledge than had all their precursors from Aristotle onward. Their methods, like those of earlier observers, were crude, but in a measure they abandoned the use of anecdotal materials in favor of direct experimental observation and systematic inquiry.
With the present century came another notable change. The experimental method be gan to be applied systematically to specific prob lems of animal psychology. Early observers experimented more or less profitably, but usually with scant control of their materials and for ill-defined purposes. It remained for an American psychologist, Thorndike, to dem onstrate the significant applicability of the method of experimentation to the study of various important problems of animal behavior. His discussion, in Intelligence,' of the associative processes of chicks, cats and dogs, at once brought the new science to the attention of biologists.
Presuppositions and The old problem of instinct versus intelligence in animals has nearly disappeared. It is generally admitted that many animals in addition to man possess intelligence as well as instinct. To prove the existence of mind in animals, or even the existence of intelligence, is not the task of the animal psychologist. Instead, he strives to describe mind in various organisms and to formulate its laws. Certain psychologists as sume that mind in some form is coextensive with life. Others believe that it appears at certain undetermined stages in organic evolu tion. For the one group of observers the chief task is that of discovering the forms and func tions of mind in different organisms; for the other there exists the additional task of deter mining what organisms are conscious. Again, it is assumed by certain observers that mind, as psychic energy, is a factor in behavior, and by others that forms of physical energy are the sole• and sufficient conditions of organic be havior, the mental phenomenon being, as Hux ley put it, merely an epiphenomenon. Still other animal psychologists make no assumption in this matter, but patiently work toward definite knowledge of the role of mind in individual life and in organic evolution.