Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Learning based upon the consequences of behavior. For example, a rat may learn to press a lever when this action produces food. Instrumental or operant behavior is the behavior by which an organism changes its environment. The particular instances of behavior that produce consequences are called responses. Classes of responses having characteristic consequences are called operant classes; responses in an operant class operate on (act upon) the environment. For example, a rat's lever-press responses may include pressing with the left paw or with the right paw, sitting on the lever, or other activities, but all of these taken together constitute the operant class called lever pressing.
Consequences of responding that produce increases in behavior are called reinforcers. For example, if an animal has not eaten recently, food is likely to reinforce many of its responses. Whether a particular event will reinforce a response or not depends on the relation between the response and the behavior for which its consequences provide an opportunity. Some consequences of responding called punishers produce decreases in behavior. The properties of punishment are similar to those of reinforcement, except for the difference in direction.
The consequences of its behavior are perhaps the most important properties of the world about which an organism can learn, but few consequences are independent of other circumstances. Organisms learn that their responses have one consequence in one setting and different consequences in another. Stimuli that set the occasion on which responses have different consequences are called discriminative stimuli (these stimuli do not elicit responses; their functions are different from those that are simply followed by other stimuli). When organisms learn that responses have consequences in the presence of one but not another stimulus, their responses are said to be under stimulus control. For example, if a rat's lever presses produce food when a light is on but not when it is off and the rat comes to press only when the light is on, the rat's presses are said to be under the stimulus control of the light. See Conditioned reflex