the process of forming behavior and a form of learning in which the actions of a person or animal change depending on the consequences of this behavior. This process is similar to Darwinian natural selection in that behavior is selected for its lifetime effects, just as species are gradually removed for the effects of survival in evolution. The concept of operant conditioning was introduced and described in detail by the American psychologist Burres Frederick Skinner in the middle of the 20th century. Together with classical (respondent) conditioning, operant conditioning became the basis of behaviorism (see Behaviorism in Chapter 5 Famous Scientists, Their Scientific Schools and Organizations in Psychological Science).