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Conditioning is a psychological term for what Ivan Pavlov described as the learning of "conditional" behavior. Most psychologists believe that there are two types of conditioning: classical conditioning and operant conditioning.
As psychologists use the term, conditioning is less prescriptive than descriptive. While Pavlov explicitly conditioned his dogs to salivate to tones, the interest in Pavlov's work is that his explicit conditioning procedures are considered useful laboratory models for what happens in the natural world. People also display natural food-related behavior in response to stimuli that are reliably paired or associated with food. Pavlov merely provided a procedure for modeling and investigating these natural phenomena in the laboratory. Pavlov's model is still used to investigating the natural behavior of organisms.
Similarly, reinforcement and punishment are understood to be natural phenomena occurring moment by moment in the lives of all animals. Laboratory studies are designed to enlighten the investigator into the nature of these phenomena rather than to discover better techniques of social, political, or economic control.
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Pavlov's Dogs
The most famous example of conditioning involves the development of conditional salivary responses in Pavlov's dogs. If a tone was reliably sounded before the dogs were fed, the dogs would eventually start salivating when they heard the tone, even if no food was present. The dog's responses (salivation) to the tone are said to be conditional upon the dogs' experience with the pairings of the tone and food. Dogs that have not experienced this condition do not salivate when they hear tones. Pavlov's dogs are therefore said to have been conditioned. Their reactions to the tone have been changed through experience.
Classical Conditioning
Classical conditioning--also called "pavlovian conditioning" or "respondent conditioning"--involves learning about the association of two or more (usually external) stimuli. Classical conditioning is generally associated with Ivan Pavlov. When two things generally occur together, encountering one can bring the other to mind (c.f., Aristotle's law of contiguity). Thus, when Pavlov's dog hears the tone, salivation and other food-related responses occur because the tone and food commonly occurred together in the dog's experience.
- In the most famous example of classical conditioning, Pavlov exposed dogs to repeated pairings of a tone and food. Again and again, a tone was audible for several seconds and then the dog was given a small portion of food. Before these pairings, the dog had innate, unconditional, food-related responses (most famously, salivation) to the food, but no food-related reactions to the tone. The food, therefore, was called an unconditional stimulus(abbreviated US or UCS), and salivation was called an unconditional response (abbreviated UR or UCR). These terms were chosen to reflect that no experience or conditions were needed for this stimulus-response relationship to occur. The food and tone were part of an unconditional reflex.
- The tone, however, initially elicited no food-related responses, and was therefore termed a neutral stimulus(abbreviated NS). After the dog experienced the pairings of the tone and food, however, the effects of the tone were changed. The previously neutral tone began to elicit salivation. The newly conditioned tone, therefore, was called a conditional stimulus (abbreviated CS) because its effects on food-related responses were conditional upon the dog's experiences. The salivation elicited by the tone, also conditional upon the dog's experience, was called a conditioned (or conditional) response (abbreviated CR). After conditioning, the tone and salivation were part of a conditional reflex.
- Extinction of a conditional reflex occurs when the conditional stimulus is repeatedly presented in the absence of the unconditional stimulus. Food-related responses to conditional stimulus generally cease over the course of extinction.
- Classical conditioning is involved in a number of important phenomena, like taste aversions, phobias, sexualfetishes, immune function, drug tolerance, and drug overdose.
Operant Conditioning
Operant conditioning, also called "instrumental conditioning", involves the modification of behavior due to the consequences of behavior. When a response or act is followed by a reinforcing consequence, the future probability of the response increases. When a response or act is followed by a punishing consequence, the future probability of the response decreases. Operant conditioning is generally associated with B.F. Skinner (1938, 1953, 1957). During reinforcement and punishment, the behavior of an organism is changed by the experience of the coincidence of the response and consequence (some would say the contingency between the response and consequence). The organism (or the response) is thus said to have been conditioned.
- A typical example of operant conditioning in the laboratory would be a comparison of the response rates of rats under two conditions. In the first, rats are allowed to press a lever with no programmed consequence. In the second, rats are allowed to press a lever with the result that each lever press is immediately followed by giving the rat a small portion of food. Generally, the rate of lever pressing is higher in the second condition. It is then said that lever pressing was reinforced by the presentation of food, or that the response-contingent presentation of food strengthed lever pressing.
- Consequences can be either reinforcing (strengthening the response) or punishing (weakening the response).
References
- Pavlov, I. P. (1927). Conditioned reflexes. (G. V. Anrep, Trans.). London: Oxford University Press.
- Skinner, B. F. (1938). The behavior of organisms: An experimental analysis. Acton, MA: Copley.
- Skinner, B. F. (1953). Science and human behavior. New York. Macmillan.
- Skinner, B. F. (1957). Verbal behavior. Englewood Cliffs, NJ: Prentice Hall.
- Siegel, S. (1978). Evidence from rats that morphine tolerance is a learned response. Journal of Comparative and Physiological Psychology, 89, 498-506.
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