ABSTRACT
The famous experiments of Ivan Pavlov's laboratory were based strictly on a single external stimulus and a single conditioned reaction, other investigators used complex stimuli and complex reactions in their studies on conditioning and learning. The most eminent cases of complex conditioning were provided by E. L. Thorndike. In spite of the fact that Thorndike called the topic of his experiments "trial-and-error learning," the behaviors he studied can be regarded as cases of the complex instrumental conditioning. The manipulatory reactions of animals of various species described by Thorndike and chain reflexes analyzed by Skinner may serve as examples of complex conditioned behavior. Feeding behavior, therefore, should be considered a complex conditioned act. The food, which is commonly called an "unconditioned stimulus," turns out to be a specific conditioned stimulus, and the act of eating becomes a conditioned instrumental reaction. A case of conditioning to the situation was observed in cats in relation to sleep.
