Quantitative analysis of behavior began with Burrhus Frederic Skinner, who invented objective ways in which to measure and observe behavior. His most significant creation was the operant chamber box. With the use of this device, Skinner was able to observe and manipulate an animal’s behavior by measuring the number of responses it produced throughout a given period of time, called the rate of response. Skinner discovered that some events increased the rate of response, while other events decreased it. The rate of response was measured by a cumulative recorder connected to the operant chamber box.
Operant conditioning was first discovered by psychologist Edward Thorndike and refers to a type of learning whereby consequences affect behavior or responses. According to Thorndike, responses are strengthened by favorable consequences and are weakened by unfavorable consequences. Thorndike referred to this relation between response and consequence as the Law of Effect, and his discovery stimulated many experimental studies in a branch of psychology called behaviorism.
Skinner was the first psychologist to devise a way in which to measure Thorndike’s law of effect. He designed the operant chamber box, which allowed an animal’s behavior to be observed, manipulated, and recorded. The operant chamber box was used for rats and other animals, and was constructed so that certain behaviors such as pressing a lever resulted in a consequence like the delivery of food. Skinner designed a cumulative recorder which could measure responses, such as lever presses and recorded response rate. He manipulated environmental factors that affected the rate of response and discovered that some factors increased response rate, while others decreased it.
Operant conditioning demonstrated that the rate of response is determined by a discriminative stimulus. In this type of conditioning, the stimulus dictates what behavior will result in a particular consequence. Skinner referred to the discriminative stimulus as an event that preceded a behavior and termed the relationship between the discriminative stimulus, behavior, and consequence as the three-term contingency.
Behaviorists study behavior by controlling the relations between the three-term contingency. Manipulating these relations results in five different outcomes: positive reinforcement, negative reinforcement, punishment, response cost, and extinction. Each of these outcomes has a different effect on the rate of response.
Positive reinforcement results in an increase in response rate because the response is followed by a pleasant stimulus. Similarly, negative reinforcement causes an increase in response rate; however, this is because it ceases a negative stimulus. Punishment leads to a decrease in the rate of response because the response results in an aversive stimulus, whereas response cost causes a decrease in response rate because the response stops a positive stimulus. Extinction causes a decrease in what was a reinforced response because that response is no longer followed by a reinforcer.