The etymology of basic concepts in the experimental analysis of behavior.

The origins of many of the basic concepts used in the experimental analysis of behavior can be traced to Pavlov's (1927/1960) discussion of unconditional and conditional reflexes in the dog, but often with substantial changes in meaning (e.g., stimulus, response, and reinforcement). Other terms were added by Skinner (1938/1991) to describe his data on the rate of lever pressing in the rat (e.g., operant conditioning, conditioned reinforcement, negative reinforcement, and response induction and differentiation) and key pecking in the pigeon (shaping). The concept of drive, however, has largely disappeared from the current literature.