Burrhus Frederic Skinner(USA)

B.F. Skinner

Behaviorism

Main articles: Behaviorism and Radical behaviorism

Skinner called his approach to the study of behavior radical behaviorism.[27] This philosophy of behavioral science assumes that behavior is a consequence of environmental histories of reinforcement, (see Applied behavior analysis). In contrast to the approach of cognitive science, behaviorism does not accept private events such as thinking, perceptions, and unobservable emotions as causes of an organism's behavior. However, in contrast to methodological behaviorism, Skinner's radical behaviorism did accept thoughts, emotions, and other "private events" as responses subject to the same rules as overt behavior. In his words:

The position can be stated as follows: what is felt or introspectively observed is not some nonphysical world of consciousness, mind, or mental life but the observer's own body. This does not mean, as I shall show later, that introspection is a kind of psychological research, nor does it mean (and this is the heart of the argument) that what are felt or introspectively observed are the causes of the behavior. An organism behaves as it does because of its current structure, but most of this is out of reach of introspection. At the moment we must content ourselves, as the methodological behaviorist insists, with a person's genetic and environment histories. What are introspectively observed are certain collateral products of those histories.

...

In this way we repair the major damage wrought by mentalism. When what a person does [is] attributed to what is going on inside him, investigation is brought to an end. Why explain the explanation? For twenty five hundred years people have been preoccupied with feelings and mental life, but only recently has any interest been shown in a more precise analysis of the role of the environment. Ignorance of that role led in the first place to mental fictions, and it has been perpetuated by the explanatory practices to which they gave rise.

Theoretical structure

Skinner's behavioral theory was largely set forth in his first book, Behavior of Organisms. Here he gave a systematic description of the manner in which environmental variables control behavior. He distinguished two sorts of behavior respondent and operant which are controlled in different ways. Respondent behaviors are elicited by stimuli, and may be modified through respondent conditioning, which is often called "Pavlovian conditioning" or "classical conditioning", in which a neutral stimulus is paired with an eliciting stimulus. Operant behaviors, in contrast, are "emitted", meaning that initially they are not induced by any particular stimulus. They are strengthened through operant conditioning, sometimes called "instrumental conditioning", in which the occurrence of a response yields a reinforcer. Respondent behaviors might be measured by their latency or strength, operant behaviors by their rate. Both of these sorts of behavior had already been studied experimentally, for example, respondents by Pavlov, and operants by Thorndike. Skinner's account differed in some ways from earlier ones, and was one of the first accounts to bring them under one roof.

The idea that behavior is strengthened or weakened by its consequences raises several questions. Among the most important are these: (1) Operant responses are strengthened by reinforcement, but where do they come from in the first place? (2) Once it is in the organism's repertoire, how is a response directed or controlled? (3) How can very complex and seemingly novel behaviors be explained?[clarification needed]

Origin of operant behavior

Skinner's answer to the first question was very much 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; a variation that is followed by reinforcement is strengthened and becomes prominent in that individual's behavioral repertoire. "Shaping" was Skinner's term for the gradual modification of behavior by the reinforcement of desired variations. As discussed later in this article, Skinner believed that "superstitious" behavior can arise when a response[clarification needed] happens to be followed by reinforcement to which it is actually unrelated.

Control of operant behavior

The second question, "how is operant behavior controlled?" arises because, to begin with, the behavior is "emitted" without reference to any particular stimulus. Skinner answered this question by saying that a stimulus comes to control an operant if it is present when the response is reinforced and absent when it is not. For example, if lever-pressing only brings food when a light is on, a rat, or a child, will learn to press the lever only when the light is on. Skinner summarized this relationship by saying that a discriminative stimulus (e.g. light) sets the occasion for the reinforcement (food) of the operant (lever-press). This "three-term contingency" (stimulus-response-reinforcer) is one of Skinner's most important concepts, and sets his theory apart from theories that use only pair-wise associations.

Explaining complex behavior

Most behavior of humans cannot easily be described in terms of individual responses reinforced one by one, and Skinner devoted a great deal of effort to the problem of behavioral complexity. Some complex behavior can be seen as a sequence of relatively simple responses, and here Skinner invoked the idea of "chaining." Chaining is based on the fact, experimentally demonstrated, that a discriminative stimulus not only sets the occasion for subsequent behavior, but it can also reinforce a behavior that precedes it. That is, a discriminative stimulus is also a "conditioned reinforcer." For example, the light that sets the occasion for lever pressing may also be used to reinforce "turning around" in the presence of a noise. This results in the sequence "noise - turn-around - light - press lever - food." Much longer chains can be built by adding more stimuli and responses.

However, Skinner recognized that a great deal of behavior, especially human behavior, cannot be accounted for by gradual shaping or the construction of response sequences. Complex behavior often appears suddenly in its final form, as when a person first finds his way to the elevator by following instructions given at the front desk. To account for such behavior, Skinner introduced the concept of rule-governed behavior. First, relatively simple behaviors come under the control of verbal stimuli: the child learns to "jump", "open the book", and so on. After a large number of responses come under such verbal control, a sequence of verbal stimuli can evoke an almost unlimited variety of complex responses.