Operant conditioning
Operant conditioning, also called instrumental conditioning, is a learning process where voluntary behaviors are modified by association with the addition (or removal) of reward or aversive stimuli. The frequency or duration of the behavior may increase through reinforcement or decrease through punishment or extinction.
Operant conditioning originated in the work of Edward Thorndike, whose law of effect theorised that behaviors arise as a result of whether their consequences are satisfying or discomforting. In the 20th century, operant conditioning was studied by behavioral psychologists, who believed that much, if not all, of mind and behaviour can be explained as a result of environmental conditioning. Reinforcements are environmental stimuli that increase behaviors, whereas punishments are stimuli that decrease behaviors. Both kinds of stimuli can be further categorised into positive and negative stimuli, which respectively involve the addition or removal of environmental stimuli.
Operant conditioning differs from classical conditioning, which is a process where stimuli are paired with biologically significant events to produce involuntary and reflexive behaviors. In contrast, operant conditioning is voluntary and depends on the consequences of a behavior.
The study of animal learning in the 20th century was dominated by the analysis of these two sorts of learning,[1] and they are still at the core of behavior analysis. They have also been applied to the study of social psychology, helping to clarify certain phenomena such as the false consensus effect.[2]
Concepts and procedures[edit]
Origins of operant behavior: operant variability[edit]
Operant behavior is said to be "emitted"; that is, initially it is not elicited by any particular stimulus. Thus one may ask why it happens in the first place. The answer to this question is like Darwin's answer to the question of the origin of a "new" bodily structure, namely, variation and selection. Similarly, the behavior of an individual varies from moment to moment, in such aspects as the specific motions involved, the amount of force applied, or the timing of the response. Variations that lead to reinforcement are strengthened, and if reinforcement is consistent, the behavior tends to remain stable. However, behavioral variability can itself be altered through the manipulation of certain variables.[15]
Questions about the law of effect[edit]
A number of observations seem to show that operant behavior can be established without reinforcement in the sense defined above. Most cited is the phenomenon of autoshaping (sometimes called "sign tracking"), in which a stimulus is repeatedly followed by reinforcement, and in consequence the animal begins to respond to the stimulus. For example, a response key is lighted and then food is presented. When this is repeated a few times a pigeon subject begins to peck the key even though food comes whether the bird pecks or not. Similarly, rats begin to handle small objects, such as a lever, when food is presented nearby.[31][32] Strikingly, pigeons and rats persist in this behavior even when pecking the key or pressing the lever leads to less food (omission training).[33][34] Another apparent operant behavior that appears without reinforcement is contrafreeloading.
These observations and others appear to contradict the law of effect, and they have prompted some researchers to propose new conceptualizations of operant reinforcement (e.g.[35][36][37]) A more general view is that autoshaping is an instance of classical conditioning; the autoshaping procedure has, in fact, become one of the most common ways to measure classical conditioning. In this view, many behaviors can be influenced by both classical contingencies (stimulus-response) and operant contingencies (response-reinforcement), and the experimenter's task is to work out how these interact.[38]