Pritchett, K., Mulder, G. B. 2004. Operant conditioning. Contemporary Topics in Laboratory Animal Science 43(4), 35-36.

Purpose. “Conditioning” simply means learning, and the term “operant” refers to something that acts upon something else. Operant conditioning, then, is a form of testing in which an animal learns that a response, such as pressing a lever, results in a consequence, such as a food pellet being delivered to the animal. This consequence is also called an unconditioned stimulus. The stimulus is “unconditioned” because animals will react to the stimulus without training. These unconditioned stimuli are often instinctive triggers such as food or pain. In most operant conditioning paradigms, the animal is given positive reinforcement; that is, it receives a reward for a correct behavior. At first, the animal being tested performs behaviors randomly. Once a behavior is exhibited that produces the unconditioned stimulus, animals may be trained or may learn to produce that behavior specifically to receive the reward. After the training period, animals will exhibit what has become a conditioned response, which means that they will perform the behavior in absence of the reward. In some cases, there may be a discriminative stimulus present in the conditioning paradigm to aid the animal in learning. The discriminative stimulus might be a light that flashes when the animal exhibits the behavior and gets the reward