The new science of behaviorism was highly influenced by its antecedents, namely, animal psychology and functionalism. Watson, the founder of behaviorism, adapted many of the original ideas of animal psychologist as well as functionalists into the basic ideas of the new science. Therefore, these ideas were not entirely new; rather they had been developing within the field of psychology for years. "Like all founders, Watson organized and promoted ideas that already were acceptable to the intellectual Zeitgeist" (Schultz, 2002, p. 247). Objectivism, mechanism, and positivism also influenced the basic ideas of the behaviorist movement. .
By the second decade of the twentieth century, the scientific Zeitgeist was shifting away from the less objective older sciences and toward the more objective science of behaviorism. The new science quickly grew popularity among the younger scientists. College students studying psychology and other sciences yearned for a chance to work with Watson. However, the popularity of behaviorism did not last very long. The behaviorist movement ultimately fell into the background as a more cognitive approach began to emerge.
The most important antecedent of behaviorism was animal psychology. Watson stated that "Behaviorism is a direct outgrowth of the studies in animal behavior during the first decade of the twentieth century" (Watson, 1929, p. 327). Thorndike, the most important researcher in animal psychology, conducted an experiment that serves as a good example of the relationship between animal psychology and behaviorism. His puzzle box was designed to study animal learning as well as animal behaviors. .
A cat was placed into the puzzle box and food was placed directly outside. Thorndike observed as the cat performed several random behaviors in order to escape from the puzzle box. Eventually, the cat would display the correct behavior of pulling a lever or chain to escape the puzzle box and get to the food outside.