PAVLOV'S DOG EXPERIMENT (CLASSICAL CONDITIONING) - PSYCHOLOGY - 2025

The experiment of Pavlov is one of the most famous of psychology. Russian physiologist Ivan Petrovich Pavlov used dogs that were presented with a sound before food. After several repetitions, the sound alone caused the dogs to salivate.

Pavlov's experiments led him to discover a form of learning that has been called classical conditioning, also known as Pavlovian conditioning. This learning is observed in most organisms to adapt to their environment.

Pavlov and dog investigated

Classical conditioning has been central to the history of psychology because Pavlov demonstrated that the learning process could be studied objectively. This allowed the application of the scientific method to psychology, separating complex blocks of behavior in order to study them objectively.

Pavlov's conclusions are fundamental and many of his premises continue to be applied in behavior modification techniques and in psychological treatments. Classical conditioning is used to treat phobias, anxiety, panic disorder, and addictions, among others.

Brief history

Before Pavlov's famous experiment, research had already been done on operant behaviors in cats. Edward Thorndike designed a device that he called a "problem box." In this box he placed hungry cats, who had to find their way out to reach the food that was outside.

When the cats, by accident at first, brushed against each other with a rope, the door would open. Little by little, and after several repetitions, the animals managed to learn the association between rubbing the rope and escaping from the box to eat. In this way, each time they came out of her faster.

Edward thorndike

Thorndike interpreted this fact as a learning test, serving as inspiration for Pavlov to develop his studies.

Pavlov was born in 1849, at first his father wanted him to become a priest. However, he deviated from this plan and graduated from medicine at age 33. His first research was focused on the digestive system, winning in 1904 the Nobel Prize in Physiology or Medicine.

Ivan Pavlov

Although his experiments on conditioned reflex and learning, which he devoted the last 30 years of his life, were what really made him famous.

Pavlov's studies were further developed by the American psychologist John B. Watson. He applied Pavlov's conclusions to humans. In 1921, Watson conducted an experiment on an 11-month-old boy known as "little Albert."

The objective was to demonstrate how specific fears could be conditioned. At first Albert was afraid of loud noises (unconditioned stimulus), but not of rats. The researchers showed the baby a rat, and when he wanted to pet it they made a loud noise behind him with an iron bar.

After several repetitions in which the noise was made when seeing the rat, little Albert cried only when he saw the rat. Days later, he generalized his answer by being scared when he saw a rabbit, a dog or a fur coat.

Description of Pavlov's experiment

Pavlov's stuffed dogs. Hygiene Museum, Saint Petersburg, Russia.

Pavlov changed the course of his investigations after a fortuitous discovery. During his studies on the digestive system, he focused on the secretion of saliva in dogs. He observed that when food was put into a dog's mouth, it would automatically start salivating.

Also, I can verify that he also salivated if he saw the food or smelled it. What's more, he gave the same response when he saw his plate of food or the person who gave it to him. He even salivated upon hearing that person's footsteps.

At first Pavlov thought that these dog responses interfered with his experiments, but later discovered that this demonstrated a form of learning. From this moment on, he directed his research to understand this phenomenon.

Pavlov and his colleagues began by trying to understand what the dog was thinking and feeling when it salivated when it saw food. However, this did not lead to any results.

Control

Then they began to conduct experiments to get a more objective view of the dog's reaction.

So that there were no other stimuli that could affect the experiment, the dog was put in an isolated room, tied up with leashes, and fitted with a device to collect and measure saliva.

The researchers were put into another room from which they could feed the dog in a bowl.

They wanted to find out if a neutral stimulus (which has no meaning for the dog or is related to food) could become a signal that food was going to appear. Thus, they wanted to observe if the dog learned to associate this stimulus with food.

They decided to use the sound of a bell as a neutral stimulus. In this way, they rang the bell just before giving the meat and powder to the dog.

Sound-response association

1-The dog salivates seeing the food. 2-The dog does not salivate at the sound of the bell. 3-The sound of the bell is shown next to the food. 4-After conditioning, the dog salivates with the sound of the bell.

After several bell-food repetitions, they discovered that the animal began to salivate only at the sound of the bell, even though the food did not appear. Thus, they achieved that a neutral stimulus, which had no meaning, elicited the same response as food: salivation.

From the experiment, Pavlov trained other dogs to salivate at other stimuli such as a light, a buzz, by touching his paw or even when he showed him a drawn circle. He found that the dog learned to associate any of these stimuli with the appearance of food, causing salivation by themselves.

There are several fundamental elements in Pavlov's experiment that you must necessarily know:

- Neutral stimulus (EN): as explained, it is a meaningless stimulus that can consist of a light, a sound, an image, etc.

- Unconditioned stimulus (ENC): it is a stimulus that causes a natural and innate reaction of the body automatically. In this case, an unconditioned stimulus is food.

- Conditioned stimulus (CS): this is the name given to the neutral stimulus when it is learned to associate with another element that causes an automatic response. For example, the sound of the bell at first was a neutral stimulus and thanks to learning, it was related to food. It thus becomes a conditioned stimulus, causing salivation by itself.

- Unconditioned reflex or unconditioned response (RNC): it is the one that is produced by the appearance of an unconditioned stimulus. The example is salivation as the dog's innate response to food in its mouth.

- Conditioned response (CR): it is the response caused by a conditioned stimulus. This occurred with the sound of the bell, which was able to trigger salivation (conditioned response) as if it were an unconditioned stimulus (food).

This whole process was called classical conditioning, being an essential element of behavioral psychology. Today it is still used to explain why certain behaviors such as those associated with phobias or addictions are established.

Conditioning processes

Building on these experiments, Pavlov and his colleagues turned to the study of classical conditioning. Thus they identified five conditioning processes:

The acquisition

This concept is related to the initial learning of the relationship between stimulus and response. Pavlov wondered how much time had to pass between the neutral stimulus (bell) and the unconditioned stimulus (food) for them to be associated.

He discovered that this period of time had to be very short. In some species half a second was sufficient.

He also wondered what would happen if the food appeared before the sound. He concluded that conditioning rarely happened in this way. The sound had to be given before the meal for the association to be learned.

Classical conditioning can be done with different species

This showed that conditioning is biologically adaptive, that is, it helps us prepare for good or bad situations. For example, for a deer, the crackling of some branches may be related to the arrival of a predator.

In humans, smells, objects, or images that are associated with sexual pleasure could become conditioned stimuli for sexual arousal. Some experiments showed that a geometric figure could generate sexual arousal if it was presented several times together with an erotic stimulus.

Extinction

Pavlov wondered what would happen if, after conditioning, the conditioned stimulus (sound) was presented without the unconditioned stimulus (food). He found that if the dog heard the sound several times without feeding it, it salivated less and less.

This is known as extinction, since the response is reduced when the conditioned stimulus stops announcing the appearance of the unconditioned stimulus.

Spontaneous recovery

Pavlov found that after the response expired, the response could be reactivated if he allowed a time-out. After that period, salivation reappeared spontaneously after the sound.

This led him to conclude that extinction weakened or repressed the conditioned response, but did not eliminate it.

Generalization

Pavlov was also able to observe that a dog conditioned to respond to a particular sound can also respond to other similar sounds.

The generalization is adaptive. For example, there were people who suffered anxiety when they saw planes similar to those with which the 9/11 attacks were carried out. It didn't have to be the planes themselves that triggered the unconditioned anxiety response.

Generalization also causes object-like stimuli that are naturally unpleasant or pleasant to lead us to feel pleasure or rejection.

Some experiments are curious. In one of them, a very attractive food was presented: the cream of a chocolate. But it was served in the form of dog excrement, which generated rejection in the subjects.

Other tests have shown that we generally view adults with childish features as affectionate and obedient.

The discrimination

Pavlov also taught dogs to respond to a specific stimulus and not to others. This is what is known as discrimination, that is, the ability to distinguish a conditioned stimulus (bell sound) from a neutral stimulus (birdsong).

Discrimination is very important for survival, since different stimuli can have very different consequences.

Applications of classical conditioning

One of Pavlov's dogs stuffed. Source: Rklawton / CC BY-SA (http://creativecommons.org/licenses/by-sa/3.0/)

The discovery of classical conditioning remains one of the most important in the history of psychology. Pavlov's postulates are the foundation of behavioral psychology and are still applied today.

Classical conditioning is a form of learning that most organisms use to adapt to their environment. This has been demonstrated in numerous studies in which the response of different organisms has been conditioned. From fish, birds, monkeys, to humans.

Some of the applications of classical conditioning are:

To treat alcoholism and other addictions

Some treatments link the sight, taste, and smell of alcohol to a drug that causes vomiting. After repeating this several times, a nausea response to alcohol develops. This treatment is called aversive therapy, and it can be helpful with other addictions as well.

Explanation of addictions

People addicted to drugs feel the need to use again when they are in places and with people with whom they had used. Especially if they had felt pleasant effects.

In addiction treatment, one of the first measures is for the addict to move away from everything related to the sensations that consumption produced.

Treatment of phobias

Classical conditioning has also been used to treat fear or phobias. For example, certain harmless insects.

In one study, patients were asked to think of bugs, which produced a fear response. This answer was soon removed because it was not associated with a sting or bite.

After the response was extinguished, photos of bugs were presented to the patients little by little until in the end the fear was lost, even getting them to touch them.

This procedure is known as systematic desensitization therapy, and it has been applied to overcome the fear of water, injections, flying, etc.

References

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3. Pavlov's Dogs. (sf). Retrieved on March 3, 2017, from Verywell: verywell.com.
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5. Pavlov's Dogs and Classical Conditioning. (sf). Retrieved on March 3, 2017, from Psychologist world: psychologistworld.com.
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