As we have seen in Chapters 3, 4, and 5, German psychologists concentrated on the experimental study of human behavior and thought processes and gave little attention to comparative psychology. Nineteenth-century British psychologists, in contrast, concentrated on comparative study and were little concerned with experimental studies of human psychology. The combination of the two approaches, which forms the basis for present-day psychology, was the achievement of American psychologists.
Comparative psychology had a promising beginning after Darwin's and Wallace's formulation of the theory of evolution, but by around 1900 interest in it had evaporated in Great Britain. Still, the comparative study of psychology continued in Continental Europe and the United States. In Europe, it was carried on by zoologists as a study of behavior, which they named ethology. Their research remained largely unknown to psychologists until about 1950. In the United States, during the first half of the twentieth century, psychologists approached the study of behavior differently. Whereas the Europeans concentrated on perception and genetic factors, the Americans studied ontogenetic development and emphasized the importance of learning. A confrontation arose, leading to an open academic debate that Robert Hinde (1995) has described as being productive for the development of psychology. I shall return to this confrontation in Chapter 19 and link ethology more closely to psychology; here, I shall merely note the connection between them.
The British comparative psychologists were particularly concerned with the following two problems: the relationship between the intellectual capacities of animals and humans, and the question of whether animals and humans possess instincts. With regard to the latter problem, the discussion revolved primarily around whether any forms of behavior could be regarded as innate. However, at the beginning of the twentieth century, researchers also asked whether behavior is elicited not only by direct outer stimulation but also by an inner state. This question became central in the study of motivation and personality. To gain a perspective on the study of motivation, we will view it in the context of the debate on instincts. These two problems that interested the early British comparative psychologists are related, but at the same time so different that I think it is appropriate to give each of them a separate treatment.