Classical conditioning
Overview
Classical conditioning (also Pavlovian or respondent conditioning, Pavlovian reinforcement) is a form of conditioning that was first demonstrated by Ivan Pavlov
Ivan Pavlov
Ivan Petrovich Pavlov was a famous Russian physiologist. Although he made significant contributions to psychology, he was not in fact a psychologist himself but was a mathematician and actually had strong distaste for the field....

 (1927). The typical procedure for inducing classical conditioning involves presentations of a neutral stimulus
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....

 along with a stimulus of some significance, the "unconditional stimulus." The neutral stimulus could be any event that does not result in an overt behavioral response from the organism under investigation.
Encyclopedia
Classical conditioning (also Pavlovian or respondent conditioning, Pavlovian reinforcement) is a form of conditioning that was first demonstrated by Ivan Pavlov
Ivan Pavlov
Ivan Petrovich Pavlov was a famous Russian physiologist. Although he made significant contributions to psychology, he was not in fact a psychologist himself but was a mathematician and actually had strong distaste for the field....

 (1927). The typical procedure for inducing classical conditioning involves presentations of a neutral stimulus
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....

 along with a stimulus of some significance, the "unconditional stimulus." The neutral stimulus could be any event that does not result in an overt behavioral response from the organism under investigation. Conversely, presentation of the significant stimulus necessarily evokes a natural response. Pavlov called these the unconditional stimulus (US) and unconditional response (UR), respectively. If the neutral stimulus is presented along with the unconditional stimulus, it would become a conditional stimulus (CS). Pavlov used the term conditional because he wanted to emphasize that learning required a dependent or conditional relationship between CS and US. If the CS and US always occur together and never alone, this perfect dependent relationship or pairing, causes the two stimuli to become associated and the organism produces a behavioral response to the CS. Pavlov called this the conditional response (CR). Because of early errors in translation of Pavlov's work from Russian to English, the term "conditioned" rather than "conditional" is very often used but is not technically correct. A perfect conditioner is not necessary for conditioning but the strength of the CR progressively degrades as the conditional relationship is weakened (see for example, Rescorla, 1967 Psychological Review).

It is often thought that the conditional response is a replica of the unconditional response but this has been disproven. The CR may be any new response to the previously neutral CS that can be clearly linked to experience with the conditional relationship with the US. It was also thought that repeated pairings are necessary for conditioning to emerge, however many CRs can be learned with a single trial as in fear conditioning and taste aversion learning.

Popular forms of classical conditioning that are used to study neural structures and functions that underlie learning and memory include fear conditioning
Fear conditioning
Fear conditioning is a behavioral paradigm in which organisms learn to predict aversive events. It is a form of learning in which an aversive stimulus is associated with a particular neutral context or neutral stimulus , resulting in the expression of fear responses to the originally neutral...

, eyeblink conditioning
Eyeblink conditioning
Eyeblink conditioning is a form of classical conditioning that has been used extensively to study neural structures and mechanisms that underlie learning and memory. The procedure is relatively simple and usually consists of pairing an auditory or visual stimulus with an eyeblink-eliciting...

, and the foot contraction conditioning of Hermissenda crassicornis
Hermissenda crassicornis
Hermissenda crassicornis is a species of small, brightly-colored, sea slug or nudibranch, a marine gastropod mollusk in the family Glaucidae.This species is also commonly known as the "opalescent sea slug."-Distribution:...

.

Origins

The original and most famous example of classical conditioning involved the saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...

ry conditioning of Pavlov's dogs. During his research on the physiology of digestion in dogs, Pavlov noticed that, rather than simply salivating in the presence of meat powder (an innate response to food that he called the unconditional response), the dogs began to salivate in the presence of the lab technician who normally fed them. Pavlov called these psychic secretions. From this observation he predicted that, if a particular stimulus in the dog's surroundings were present when the dog was presented with meat powder, then this stimulus would become associated with food and cause salivation on its own. In his initial experiment, Pavlov used a bell to call the dogs to their food and, after a few repetitions, the dogs started to salivate in response to the bell.

Forward conditioning

Learning is fastest in forward conditioning. During forward conditioning the onset of the CS precedes the onset of the US. Two common forms of forward conditioning are delay and trace conditioning.
  • Delay conditioning: In delay conditioning the CS is presented and is overlapped by the presentation of the US.
  • Trace conditioning: During trace conditioning the CS and US do not overlap. Instead, the CS is presented, a period of time is allowed to elapse during which no stimuli are presented, and then the US is presented. The stimulus-free period is called the trace interval. It may also be called the conditioning interval.

Simultaneous conditioning

During simultaneous conditioning, the CS and US are presented and terminated on the same time

Backward conditioning

Backward conditioning occurs when a conditional stimulus immediately follows an unconditional stimulus. Unlike traditional conditioning models, in which the conditional stimulus precedes the unconditional stimulus, the conditional response tends to be inhibitory. This is because the conditional stimulus serves as a signal that the unconditional stimulus has ended, rather than a reliable method of predicting the future occurrence of the unconditional stimulus.

Temporal conditioning

The US is presented at regularly timed intervals, and CR acquisition is dependent upon correct timing of the interval between US presentations. The background, or context, can serve as the CS in this example.

Unpaired conditioning

The CS and US are not presented together. Usually they are presented as independent trials that are separated by a variable, or pseudo-random, interval. This procedure is used to study non-associative behavioral responses, such as sensitization
Sensitization
Sensitization is an example of non-associative learning in which the progressive amplification of a response follows repeated administrations of a stimulus. An everyday example of this mechanism is the repeated tonic stimulation of peripheral nerves that will occur if a person rubs his arm...

.

CS-alone extinction
Extinction (psychology)
Extinction is the conditioning phenomenon in which a previously learned response to a cue is reduced when the cue is presented in the absence of the previously paired aversive or appetitive stimulus.-Fear conditioning:...

The CS is presented in the absence of the US. This procedure is usually done after the CR has been acquired through "forward conditioning" training. Eventually, the CR frequency is reduced to pre-training levels. Essentially, the stimulus is presented until habituation
Habituation
Habituation can be defined as a process or as a procedure. As a process it is defined as a decrease in an elicited behavior resulting from the repeated presentation of an eliciting stimulus...

 occurs.

Generalization in classical conditioning

After conditioning, subjects that show the conditional response not just to the original conditional stimulus but also to new stimuli that resemble that stimulus are displaying what is called generalization.

Discrimination in classical conditioning

In classical conditioning, discrimination is when any life form can be taught to differentiate between very alike, but different stimuli. Therefore, we get the development of a CR when one stimulus is presented, however not when the other is. .

Extinction and spontaneous recovery classical conditioning

It was found that that without the US (food in this case), the bell elicited less and less salivation on subsequent trials eventually becoming extinct as a behavior. Even with extinction, there was no clear evidence that the animal returned to its fully unconditioned state. The conditional reflex can be partially renewed after a certain time period has passed, a phenomenon known as spontaneous recovery. Pavlov concluded that the conditional reflex is not entirely lost during extinction, but possibly inhibited. In this state, the behavior can be recovered after the passage of time or the recurrence of the unconditional stimuli.

Latent inhibition conditioning

In this procedure, a CS is presented several times before paired CS–US training commences. The pre-exposure of the subject to the CS before paired training slows the rate of CR acquisition relative to organisms that are not CS pre-exposed. Also see Latent inhibition
Latent inhibition
Latent inhibition is a technical term used in Classical conditioning. A stimulus that has not had any significance in the past takes longer to acquire meaning than a new stimulus...

 for applications.

Conditioned inhibition conditioning

Three phases of conditioning are typically used:
Phase 1
A CS (CS+) is paired with a US until asymptotic CR levels are reached.


Phase 2
CS+/US trials are continued, but interspersed with trials on which the CS+ in compound with a second CS, but not with the US (i.e., CS+/CS− trials). Typically, organisms show CRs on CS+/US trials, but suppress responding on CS+/CS− trials.


Phase 3
In this retention test, the previous CS− is paired with the US. If conditioned inhibition has occurred, the rate of acquisition to the previous CS− should be impaired relative to organisms that did not experience Phase 2.

Blocking

This form of classical conditioning involves two phases.
Phase 1
A CS (CS1) is paired with a US.


Phase 2
A compound CS (CS1+CS2) is paired with a US.


Test
A separate test for each CS (CS1 and CS2) is performed. The blocking effect is observed in a lack of conditional response to CS2, suggesting that the first phase of training blocked the acquisition of the second CS.

Behavioral therapies

In human
Human
Humans are the only living species in the Homo genus...

 psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

, implications for therapies and treatments using classical conditioning differ from operant conditioning
Operant conditioning
Operant conditioning is a form of psychological learning during which an individual modifies the occurrence and form of its own behavior due to the association of the behavior with a stimulus...

. Therapies associated with classical conditioning are aversion therapy
Aversion therapy
Aversion therapy is a form of psychological treatment in which the patient is exposed to a stimulus while simultaneously being subjected to some form of discomfort...

, flooding
Flooding (psychology)
Flooding is a form of behavior therapy and based on the principles of respondent conditioning. It is sometimes referred to as exposure therapy or prolonged exposure therapy. As a psychotherapeutic technique, it is used to treat phobia and anxiety disorders including post-traumatic stress disorder...

 and systematic desensitization
Systematic desensitization
Systematic desensitization is a type of behavioral therapy used in the field of psychology to help effectively overcome phobias and other anxiety disorders. More specifically, it is a type of Pavlovian therapy / classical conditioning therapy developed by a South African psychiatrist, Joseph Wolpe...

.

Classical conditioning is short-term, usually requiring less time with therapists and less effort from patients, unlike humanistic
Humanistic psychology
Humanistic psychology is a psychological perspective which rose to prominence in the mid-20th century, drawing on the work of early pioneers like Carl Rogers and the philosophies of existentialism and phenomenology...

 therapies. The therapies mentioned are designed to cause either aversive feelings toward something, or to reduce unwanted fear and aversion.

Conditional drug response

Certain drug reactions can also be partly viewed in terms of classical conditioning. Conditional drug reactions can occur if a drug is repeatedly paired with a stimulus. After a time, the stimulus alone can evoke in the drug user the same effects as the drug itself. This is sometimes the case with caffeine; habitual coffee drinkers find that simply the smell of coffee gives them a feeling of alertness (Psychology 102). In other cases, repeated use of a drug can cause the body to develop a compensatory reaction to the drug in which the body enters a state that will counterbalance the effects of the drug. For example, if a drug causes the body to become less sensitive to pain, the compensatory reaction will be one that makes the user more sensitive to pain, to counteract the drug's pain-relieving effects. Thus, in the context of drug use, this compensatory reaction is used to restore the body to homeostasis. Upon the repeated pairing of a drug and a stimulus, over time the stimulus, which has come to be associated with the effects of drug use, can trigger compensatory reactions in the body that counteract the effects of the drugs and thereby contributing to drug tolerance. Additionally, in the cases where the stimulus is absent at the time of drug use, the user is likely to overdose since there is no stimulus to elicit the compensatory reaction to counteract the effects of the drug (Psychology 103).

Conditional hunger

Signals that consistently precede food intake can become conditional stimuli for a set of bodily responses that prepares the body for food and digestion. These reflexive responses include the secretion of digestive juices into the stomach and the secretion of certain hormones into the blood stream, and they induce a state of hunger (Psychology 104). An example of conditional hunger is the "appetizer effect." Any signal that consistently precedes a meal, such as a clock indicating that it is time for dinner, can cause people to feel hungrier than before the signal. The lateral hypothalamus (LH) is involved in the initiation of eating. The nigrostriatal pathway, which includes the substantia nigra, the lateral hypothalamus, and the basal ganglia have been shown to be involved in hunger motivation.

Conditional sexual response

From an evolutionary viewpoint, classical conditioning involves an individual preparing itself for important biological events in the individual's life, particularly sexual activity. For example, a stimulus that is conditioned to occur before sexual interaction prepares animals both mentally (increased sex drive) and physically (sexually aroused body responses). Sexual arousal can actually be conditioned in human subjects by pairing a conditional stimulus like a picture of a jar of pennies with an unconditional stimulus like an erotic film clip. Similar experiments involving blue gourami fish and domesticated quail have shown that these conditioning techniques often increase the number of offspring, compared to unconditioned males. These findings could possibly be beneficial in terms of conditioning techniques aimed to increase fertility rates in infertile individuals and endangered species (Psychology, Gray).

Theories of classical conditioning

Stimulus–response (S–R) theory suggests that the CS is associated with the US within the brain, without involving conscious thought. The second, stimulus–stimulus (S–S) theory, involves cognitive activity in which the CS is associated to the concept of the US, a subtle but important distinction.

S–S theory is a theoretical model of classical conditioning that suggests a cognitive component is required to understand classical conditioning, while S–R theory proposes that a cognitive component is merely at play. S–R theory suggests that an animal can learn to associate a CS with the impending arrival of the associated US, resulting in an observable behavior such as salivation. S–S theory suggests that the animal salivates to the bell because it is associated with the concept of the US, which is a very fine but important distinction.

In popular culture

One of the earliest literary references to classical conditioning can be found in the comic novel The Life and Opinions of Tristram Shandy, Gentleman
The Life and Opinions of Tristram Shandy, Gentleman
The Life and Opinions of Tristram Shandy, Gentleman is a novel by Laurence Sterne. It was published in nine volumes, the first two appearing in 1759, and seven others following over the next 10 years....

(1759) by Laurence Sterne
Laurence Sterne
Laurence Sterne was an Irish novelist and an Anglican clergyman. He is best known for his novels The Life and Opinions of Tristram Shandy, Gentleman, and A Sentimental Journey Through France and Italy; but he also published many sermons, wrote memoirs, and was involved in local politics...

. The narrator Tristram Shandy explains how his mother was conditioned by his father's habit of winding up a clock before having sex with his wife:
Another example is in the dystopian novel, A Clockwork Orange
A Clockwork Orange
A Clockwork Orange is a 1962 dystopian novella by Anthony Burgess. The novel contains an experiment in language: the characters often use an argot called "Nadsat", derived from Russian....

in which the novel's anti-hero
Anti-hero
In fiction, an antihero is generally considered to be a protagonist whose character is at least in some regards conspicuously contrary to that of the archetypal hero, and is in some instances its antithesis in which the character is generally useless at being a hero or heroine when they're...

 and protagonist
Protagonist
A protagonist is the main character of a literary, theatrical, cinematic, or musical narrative, around whom the events of the narrative's plot revolve and with whom the audience is intended to most identify...

, Alex, is given a solution to cause severe nausea, and is forced to watch violent acts. This renders him unable to perform any violent acts without inducing similar nausea.

Another example is from the TV series The Office. In the episode Phyllis' Wedding Jim conditions Dwight to want a breath mint whenever there is a computer chime.

See also

  • Behaviorism
    Behaviorism
    Behaviorism , also called the learning perspective , is a philosophy of psychology based on the proposition that all things that organisms do—including acting, thinking, and feeling—can and should be regarded as behaviors, and that psychological disorders are best treated by altering behavior...

  • Eyeblink conditioning
    Eyeblink conditioning
    Eyeblink conditioning is a form of classical conditioning that has been used extensively to study neural structures and mechanisms that underlie learning and memory. The procedure is relatively simple and usually consists of pairing an auditory or visual stimulus with an eyeblink-eliciting...

  • Fear conditioning
    Fear conditioning
    Fear conditioning is a behavioral paradigm in which organisms learn to predict aversive events. It is a form of learning in which an aversive stimulus is associated with a particular neutral context or neutral stimulus , resulting in the expression of fear responses to the originally neutral...

  • Latent inhibition
    Latent inhibition
    Latent inhibition is a technical term used in Classical conditioning. A stimulus that has not had any significance in the past takes longer to acquire meaning than a new stimulus...

  • Learned helplessness
    Learned helplessness
    Learned helplessness, as a technical term in animal psychology and related human psychology, means a condition of a human person or an animal in which it has learned to behave helplessly, even when the opportunity is restored for it to help itself by avoiding an unpleasant or harmful circumstance...

  • Nocebo
    Nocebo
    In medicine, a nocebo reaction or response refers to harmful, unpleasant, or undesirable effects a subject manifests after receiving an inert dummy drug or placebo...

  • Measures of conditioned emotional response
    Measures of conditioned emotional response
    In experimental psychology, there are multiple measures of conditioned emotional response used by researchers as the measure of conditioned emotional response in a subject in classical conditioning experiments.-Movement ratio:...

  • Operant conditioning
    Operant conditioning
    Operant conditioning is a form of psychological learning during which an individual modifies the occurrence and form of its own behavior due to the association of the behavior with a stimulus...

  • Placebo (origins of technical term)
  • Quantitative analysis of behavior
    Quantitative Analysis of Behavior
    Quantitative analysis of behavior is the quantitative form of the experimental analysis of behavior. This has become the dominant scientific approach to behavior analysis. It represents behavioral research using quantitative models of behavior. The parameters in the models hopefully have...

  • Rescorla-Wagner model of conditioning
    Rescorla-Wagner model
    The Rescorla–Wagner model is a model of classical conditioning in which the animal is theorized to learn from the discrepancy between what is expected to happen and what actually happens. This is a trial-level model in which each stimulus is either present or not present at some point in the trial...

  • Reward system
    Reward system
    In neuroscience, the reward system is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects...

  • Preparedness (learning)
    Preparedness (learning)
    In psychology, preparedness is a concept developed to explain why certain associations are learned more readily than others. For example, phobias related to survival, such as snakes, spiders, and heights, are much more common and much easier to induce in the laboratory than other kinds of fears....

  • Second-order conditioning
    Second-order conditioning
    In classical conditioning, second-order conditioning or higher-order conditioning is a form of learning in which a stimulus is first made meaningful or consequential for an organism through an initial step of learning, and then that stimulus is used as a basis for learning about some new stimulus...

  • Taste aversion
    Taste aversion
    Conditioned taste aversion, also known as Garcia effect , and as "Sauce-Bearnaise Syndrome", a term coined by Seligman and Hager, is an example of classical conditioning or Pavlovian conditioning...

  • Edwin B. Twitmyer
    Edwin B. Twitmyer
    Edwin Burket Twitmyer was Professor of Psychology and Director of the Psychological Laboratory and Clinic at the University of Pennsylvania...

  • Proboscis extension reflex
    Proboscis extension reflex
    Proboscis extension reflex is when a bee extends her proboscis as a reflex to antennal stimulation. It is evoked when a sugar solution is touched to a bee's antenna.- Use of PER :...


Further reading


External links

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