SOURCE: "Psychology as the Science of Behavior: Ivan Pavlov and John B. Watson," in Pioneers of Psychology, W. W. Norton & Company, 1979, pp. 295-338.

In the following excerpt, Fancher surveys Pavlov's life, experiments, theories, and influence.

At the turn of the present century, the Russian physiologist Ivan Petrovitch Pavlov (1849-1936) was on the horns of a dilemma. He had just completed a monumental series of studies on the physiology of digestion that would win him a Nobel Prize, and he was looking for new scientific challenges. Some incidental observations he had made in the course of those studies seemed to point to a new and promising area, but Pavlov was uncertain about its scientific propriety.

The new idea was to study a class of responses that Pavlov initially called "psychic secretions." His earlier research had concerned itself only with innate digestive responses that occurred in response to clear-cut and...