The Evolution of Classical Conditioning

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A person can learn in both conscious and unconscious ways. Behaviors, attitudes, ideas, and the absorption of new information can be learned with or without a person’s knowledge.

Classical conditioning is a form of unconscious learning that was popularized by Ivan Pavlov, a Russian physiologist. Today, classical conditioning is often used as a therapeutic technique to change or modify negative behaviors, such as substance use.

Read on to find out more about classical conditioning and how it’s used today.

a therapy specialist taking notes while listening to a tattooed young person with emotional and behavioral problems

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What Is Pavlov’s Theory?

When Pavlov discovered classical conditioning, he was performing unrelated research on dog digestion. He noticed how the dogs' reactions to the food they were being fed evolved based on stimuli in the test environment, which had nothing to do with the actual food he was giving to them.

At the beginning of the experiment, the dogs would salivate only when presented with food. Later on, other neutral noises, such as the food cart coming into the testing area, began to make them salivate because it always occurred prior to the dogs being fed.

To test out whether the dogs were actually being conditioned by external and unrelated stimuli, Pavlov set up an experiment that involved ringing a bell right before giving food to the dogs. After some time, the dogs began salivating after hearing the bell without seeing or hearing the food cart come into the room.

The results of this discovery led Pavlov to develop the theory that behavior could be learned simply by introducing consistent stimuli.

The Pavlovian Impact

Classical conditioning is often considered the most important discovery in the history of psychology, because it forms the basis of behavioral psychology. It can be used in a variety of different ways, from helping people with mental health disorders to keeping domestic livestock safe from ravenous coyotes. Because of Pavlov's findings on classical conditioning, the process is also sometimes called Pavlovian conditioning.

Terms to Know 

To fully understand the process behind classical conditioning, there are several terms you need to know. They include:

  • Unconditioned stimulus: Unconditioned stimulus occurs when you have an automatic response to a certain stimulus in a natural and unlearned way. For example, if you cut an onion and your eyes tear up, that is an automatic response and thus an unconditioned stimulus.
  • Neutral stimulus: A neutral stimulus in the environment does not evoke any response by itself. It can, however, be used later to trigger a response.
  • Conditioned stimulus: A conditioned stimulus is one that used to be neutral but has since garnered a response because it has been connected to a stimulus that evokes that specific response.
  • Unconditioned response: An unconditioned response is automatic, meaning that it is a type of response that just happens naturally. Using food as an example, if you smell food you like, your mouth may begin to water in anticipation of the meal. That is automatic.
  • Conditioned response: This response is learned based on a neutral-to-conditioned stimulus.

Key Principles

The five key principles of classical conditioning are:

  • Acquisition: The initial stage of learning
  • Extinction: When the conditioned response is slowly unlearned because the unconditioned stimulus is no longer paired with the conditioned stimulus
  • Spontaneous recovery: The emergence of a conditioned response after a period of time when the conditioned stimulus was not used
  • Generalization: Occurs when stimuli are similar to the conditioned stimulus and evoke a similar response
  • Discrimination: The ability to tell the difference between the conditioned stimulus and similar stimuli

What Is the Classical Conditioning Process?

If the classical conditioning process is successful, a learned response will form based on unconscious associations between two different stimuli. There are three steps in this process: before conditioning, during conditioning, and after conditioning.

Before Conditioning

Prior to the conditioning, a naturally occurring unconditioned stimulus must be present.

In the case of Pavlov’s research, it was simply presenting the dogs with food. The food being presented led to an unconditioned response, which was the dogs' salivating. This response is automatic and not learned.

A neutral stimulus is also present but has not yet evoked any response at all. The neutral stimulus needs to be paired with the unconditioned stimulus for it to begin causing a response.

During Conditioning

The second phase of classical conditioning involves the pairing of the unconditioned and neutral stimulus to drive a response.

In Pavlov’s experiment, for instance, he used a bell. The bell acts as a neutral stimulus, whereas presenting the food to the dogs acts as an unconditioned stimulus.

When the dogs hear the bell and then are presented with food, they unconsciously form a connection between the two stimuli. The neutral stimuli—the bell—evolves into a conditioned stimulus. The dogs now respond to the bell in the same way they did when given food because they view the bell as part of the process.

After Conditioning

Once the conditioning has occurred and the association is made between the unconditioned and conditioned stimulus, the unconditioned stimulus can be removed from the equation entirely and the response will be the same. A response is now triggered by using the conditioned stimulus by itself.

For example, the dogs in Pavlov’s experiment soon salivated at hearing only the sound of the bell because they associated it with getting fed.

Classical Conditioning

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What Are Real-World Applications of Classical Conditioning?

There are many areas in which classical conditioning is used today, including in mental health treatment, education, and pet training.

Mental Health 

Classical conditioning may be used in mental health applications because it can be useful to help treat and understand the development of certain disorders.

Research has shown classical conditioning principles to be helpful in treating:

Certain therapies are used to help counter-condition some people with various mental health disorders. They include exposure and aversion therapy.

In exposure therapy, people with anxiety and phobias are exposed to what they fear most in a safe environment until they are no longer afraid. Aversion therapies replace positive experiences drawn from negative behaviors into negative responses.

For example, if a person misuses alcohol, they may be given a medication that causes them to feel ill every time they drink it. This negative response will, in turn, condition them to no longer desire alcohol.

Classical Conditioning and Phobias

One older study looked at how classical conditioning could be used in the fear and anxiety response. It examined the fear levels of a child who was exposed to a rat in a calm environment. The child felt no fear toward the rat. However, when the child was exposed to the rat repeatedly along with loud and scary noises, the child began to fear the rat, as well as other similar-looking fuzzy objects. This shows that although classical conditioning can be helpful in treating mental health disorders, it can also lead to the development of new phobias.


In school systems, classical conditioning can be used to provide students with positive associations within their learning experiences.

For example, if a student has to give a presentation in front of the class but feels great anxiety because of it, a teacher can develop certain positive stimuli that can later be associated with public speaking.

The student, in turn, learns to associate public speaking with a positive environment.

Taste Aversions

Taste aversions can improve the survival of a species. One particular study demonstrated this using rats. The rats in question were exposed to a type of radiation that caused them to feel nauseated. Following their exposure, the rats no longer liked flavored water when it was presented to them at the same time as the radiation.

The radiation acts like an unconditioned stimulus, because it triggers feelings of automatic nausea. The flavored water acts as a conditioned stimulus, because when the rats were exposed to only the flavored water without the radiation, they experienced nausea in the same way as if the radiation were present.


Advertisers will often use classical conditioning to encourage consumers to buy their product.

For example, a commercial may show a product that people enjoy using. Eventually, a person will associate happy people having fun with that product. This association of good feelings could alter a person’s perspective and lead them to buy the product in question.

Advertising will also use music as a form of classical conditioning. Upbeat and joyful music will eventually be associated with feelings of happiness for the people that see the ad. They will then associate that company with good emotions.

Placebo Effects

Classical conditioning has also been researched as a part of the placebo effect. The research surrounding this area of study has found that classical conditioning can essentially cause the placebo effect to occur.

One study looked at classical conditioning in relation to the placebo effect and pain modulation and found that a person can reduce their pain if given certain cues that are associated with lower levels of pain.

Pet Training

Classical conditioning is a highly popular tool used to train pets to be more obedient. It is performed to assist your dog in unconsciously engaging in good behaviors.

Classical Conditioning and Your Pet

Classical conditioning is used to help train pets in various ways. However, it can also occur by accident. For example, if you pick up your keys prior to taking them for a walk, they may not initially react to your keys at all. Eventually, though, the sound of keys will trigger them to believe that they are going for a walk, which will cause a response.


Classical conditioning is a form of unconscious learning style. It was popularized by physiologist Ivan Pavlov after he accidentally stumbled upon it during an unrelated experiment using dogs. The theory maintains that people can be directed to unconsciously respond to a certain stimulus different from what would trigger the response naturally.

The idea of classical conditioning has been used in various real-world applications, especially mental health. Others include the education system, advertising, pet training, placebos, and taste aversions.

A Word From Verywell 

While Pavlov’s dogs led to the discovery of classical conditioning, not all people will react in exactly the same way. However, there are many real-world ways to utilize classical conditioning for your benefit. Pavlov’s discovery shaped behavioral psychology, but as the study of classical conditioning continues, more gaps will be filled in when it comes to understanding human behavior.

Frequently Asked Questions

  • How is classical conditioning different from operant learning?

    Classical and operant conditioning differ in a few ways. Where classical conditioning uses stimuli to help evoke an involuntary response, operant conditioning uses behavior and consequences as a way of conditioning. For example, different from Pavlov’s dogs, operant conditioning would involve rewards for good behaviors and punishment for bad behaviors.

  • When would classical conditioning be harmful?

    Classical conditioning can be harmful when a stimulus that presents no danger to a person becomes associated with something that causes great fear. For example, if a person eats food and gets food poisoning, it’s possible that they would get an aversion to that food, even though it is not always harmful to their health.

  • What’s a simple way to remember how classical conditioning works?

    Classical conditioning may seem like a complicated concept, however, the process itself is quite easy to remember. When two stimuli are paired together to evoke the natural response of the first stimulus, it creates a conditioned response.

    Think of Pavlov’s dogs: They were given food causing them to salivate. The food was then paired with a bell, which also led them to salivate. When the bell rang, they eventually thought that it meant they were getting food, even when no food was presented, and they salivated anyway.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Angelica Bottaro
Angelica Bottaro is a professional freelance writer with over 5 years of experience. She has been educated in both psychology and journalism, and her dual education has given her the research and writing skills needed to deliver sound and engaging content in the health space.