operant conditioning

operant conditioning, in psychology and the study of human and animal behaviour, a mechanism of learning through which humans and animals come to perform or to avoid performing certain behaviours in response to the presence or absence of certain environmental stimuli. The behaviours are voluntary—that is, the human or animal subjects decide whether to perform them—and reversible—that is, once a stimulus that results in a given behaviour is removed, the behaviour may disappear. Operant conditioning thus demonstrates that organisms may be guided by consequences, whether positive or negative, in the behaviours they produce.

Operant versus classical conditioning

Operant conditioning differs from classical conditioning, in which subjects produce involuntary and reflexive responses related to a biological stimulus and an associated neutral stimulus. For example, in experiments based on the work of the Russian physiologist Ivan Pavlov (1849–1936), dogs can be classically conditioned to salivate in response to a bell. Food is presented to a dog at the sounding of a bell, the dog salivates involuntarily in response to the food, and over time the animal comes to associate food with the bell ringing. Eventually, the dog salivates involuntarily in response to the ringing bell when food is not present.

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animal learning: Classical and instrumental conditioning

Operant conditioning, in contrast, involves learning to do something to obtain or avoid a given result. For example, through operant conditioning a dog can be taught to offer a paw to receive a food treat. The main distinction between the two conditioning methods is thus the kind of reaction that results. Classical conditioning involves involuntary reactions to a stimulus, whereas operant conditioning involves a change in behaviour to either gain a reward or avoid punishment.

History

The study of operant conditioning began with the work of the American psychologist Edward L. Thorndike (1874–1949). In 1905 Thorndike formulated the law of effect, which states that, given a certain stimulus, animals repeat behavioral responses with positive (desired) results while avoiding behaviours with negative (unwanted) results.

The American psychologist B.F. Skinner (1904–90) built on Thorndike’s law of effect and formalized the process of operant conditioning, which he understood to be the explanatory basis of human behaviour (see behaviourism). In the 1930s he invented the so-called Skinner box, a cage with a closely controlled environment that included no stimuli other than those under study. He placed animals such as rats or pigeons in the box and provided stimuli and rewards to elicit certain behaviours such as pressing a bar or pecking at a light.

Methods and applications

Operant conditioning is dependent upon behaviour enhancers and behaviour suppressors. Behaviour enhancers encourage a desired action, whereas behaviour suppressors discourage an undesired action. Both behaviour enhancers and behaviour suppressors can be either positive or negative. In this context, the terms positive and negative do not represent value judgments; they instead refer to stimuli that are added or present (positive) or removed or absent (negative). Thus, an enhancer may be the addition of a desired consequence or the removal of an undesired consequence, and a suppressor may be the addition of an undesired consequence or the removal of a desired consequence.

The notions of positive and negative enhancement or suppression inform five possible strategies for accomplishing operant conditioning. Positive reinforcement (enhancement) occurs when the subject receives a reward for a desired behaviour. An example is when a dog gets a treat for doing a trick. Negative reinforcement is the absence or removal of an annoying or harmful stimulus when a desired action is performed. An example is using a loud alarm as an incentive to get out of bed in the morning. Positive punishment (suppression) happens when a subject performs an undesired behaviour and receives a negative stimulus. Thus, students who talk too much in class may be required to sit next to the teacher’s desk. Negative punishment occurs when a subject performs an undesired behaviour and a positive stimulus is removed. Thus, teenagers may be punished for bad behaviour by removal of their driving privileges.

Extinction takes place when a behaviour is no longer rewarded, and its occurrences gradually decline in number until it is no longer performed. The subject may initially repeat the behaviour with greater frequency in an attempt to receive a reward, then perform it less frequently, and then eventually stop. For example, people who tell unwanted, off-colour jokes are more likely to stop their behaviour if they consistently receive no attention, positive or negative, after telling such a joke.

Another component of operant conditioning is the reinforcement schedule, of which there are two kinds. Interval schedules reward behaviour after a given amount of time has passed since the previous instance of the behaviour. Ratio schedules require the organism to complete a certain number of repetitions of the behaviour before receiving the reward.

Besides the study of human and animal motivations and behaviours, operant conditioning has many applications. It underlies techniques used in animal training, pedagogy, parenting, and psychotherapy.