Ivan Pavlov and His Dogs

At the turn of the 20th century, a Russian physiologist made a discovery that would fundamentally change how we understand learning and behavior.

What began as research into digestion unexpectedly revealed that animals, and humans, could be trained to associate one stimulus with another.

The experiments involved bells, food, and a group of very famous dogs. Yet the implications reached far beyond the laboratory, influencing psychology, education, and even marketing.

Learn more about Ivan Pavlov and the surprising experiments that reshaped our understanding of the mind on this episode of Everything Everywhere Daily.

Ivan Petrovich Pavlov was born the first of 10 children in Ryazan, Russia, on September 26, 1849. His father was a Russian Orthodox Priest, and his mother was a homemaker.

Pavlov started school at age 11, where he demonstrated a deep love for learning, a desire he described as “the instinct for research.” He began his education at Ryazan Church Schools and later at a theological seminary.

Pavlov ultimately abandoned his religious education due to the works of Russian Literary Critic Dmitry Pisarev and Russian physiologist Ivan Sechenov. He decided to abandon his religious education and devote himself to science.

In 1870, Pavlov enrolled in the University of Saint Petersburg, where he studied natural science. While at school, he excelled, receiving a prestigious award for his research on the nerves of the pancreas.

By 1875, Pavlov had earned his degree in natural science and decided to continue his education. Primarily interested in physiology, Pavlov attended the Russian Imperial Academy of Medical Surgery.

While in school, Pavlov worked as a laboratory assistant to Konstantin Ustimovich, who worked in the Veterinary Institute’s physiological department. During his time at the Veterinary Institute, Pavlov worked on his medical dissertation, where he studied the circulatory system.

Following this research, Pavlov served as the chief of the physiological laboratory at the clinic until he graduated in 1879 with a gold medal for his research at the Medical Military Academy. He then won a fellowship that allowed him to complete post-graduate work at the academy.

After completing his doctorate, Pavlov moved to Germany, where he studied for two years. He worked with Carl Ludwig and Eimear Kelly at Heidenhein Laboratories, where he studied the digestion of dogs.

After two years in Germany, Pavlov returned to Russia where he was appointed Professor of Pharmacology at the Military Medical Academy in 1890. He held this position for five years before becoming chair of physiology in 1895, a position he held for three decades.

In 1891, Pavlov was given the opportunity to organize and direct the Department of Physiology at the Institute of Experimental Medicine in St. Petersburg. Pavlov held this role for 45 years. Under his leadership, the institute became one of, if not the most important, centers for physiological research.

Ivan Pavlov received the 1904 Nobel Prize in Medicine for his groundbreaking research on the physiology of digestion.

Something you might have noticed is that up till this point, I’ve described the career of an eminent physiologist who went so far as to win the Nobel Prize in his field.

What I haven’t mentioned is the field he is most associated with…psychology.

It was an accidental discovery that led to a fundamental shift in his field of study, eventually culminating in the development of the concept of Pavlovian conditioning.

In the 1890s, Pavlov began testing dogs’ salivation in response to feeding. This was part of his research into digestion. To measure the amount of saliva produced by the dog, Pavlov placed a small test tube in the dog’s mouth. He pressed the tube against the dog’s cheek and measured the amount of saliva produced during feeding.

Pavlov had expected the dogs to salivate when they saw food, but had noticed that they salivated before eating, just from hearing their owner approach.

This realization led Pavlov to conclude that the dogs had learned to respond to any stimulus associated with food. He called this phenomenon “psychic secretions.”

However, Pavlov sought to demonstrate this phenomenon scientifically. He conducted a controlled experiment to determine whether he could elicit a response from a dog to a neutral stimulus. This stimulus could have no natural connection to food, because if it did, the results of the experiment would be invalid.

A bell was ultimately chosen as the neutral stimulus.

The idea behind the experiment was that there were things a dog didn’t need to directly learn. For example, a dog does not need to learn to salivate when it sees food; it does so naturally as a reflex.

To test this idea, Pavlov set up an experiment. To maintain the integrity of the experiment, all the dogs were placed in secluded environments and secured with harnesses to prevent potential distractions.

A food bowl was placed in front of the dog, with a surgically attached tube to its salivary glands. By doing this, Pavlov could divert the dogs’ saliva away from their throats and into a measuring container.

The measurements were taken on a rotating drum, allowing Pavlov to monitor saliva volume in real time.

Before conducting the experiment, the different variables need to be formally described. These variables were known as the unconditioned stimulus, the unconditioned response, and the neutral stimulus.

In Pavlov’s experiment, the unconditioned stimulus was food. An unconditioned stimulus is something that occurs naturally and automatically elicits a response without prior learning.

The automatic reaction to the unconditioned stimulus is the unconditioned response. This is a built-in, instinctive reaction. For example, when a dog smells or tastes food, it naturally salivates. It cannot be helped; therefore, it is an unconditioned response.

Finally, a neutral stimulus is something that does not cause any specific reaction on its own. In Pavlov’s experiment, the bell was the neutral stimulus because it did not elicit salivation in the dogs at first.

So, at the base of the experiment, the unconditioned stimulus, or the food, should result in an unconditioned response, which is to produce saliva. Simultaneously, the bell, which is a neutral stimulus, should elicit no response in the dog.

The second part of the experiment involved the neutral stimulus becoming associated with the unconditioned stimulus through repeated trials. This was done by repeatedly introducing a neutral stimulus, in this case the bell, then immediately delivering the unconditioned stimulus, food.

Because of the short interval between the neutral stimulus and the unconditioned stimulus, Pavlov believed the brain would begin to associate the two. In this experiment, the dog will associate the sound of the bell with its feeding time and begin to salivate.

After numerous trials, the neutral stimulus will no longer be neutral; instead, it will have a learned association with the unconditioned stimulus. Because of this learned association, it would then be considered to be a conditioned stimulus.

It is a conditioned stimulus because the dog will salivate when it hears the bell, regardless of whether food is present.

This newly learned reaction, salivating at the sound of the bell, is called a conditioned response, or a reaction developed through learning. The reaction, to produce saliva, is exactly the same as the unconditioned response, which is the natural, automatic reaction to food, and it is only considered different because the conditioned response is learned rather than an automatic biological one.

Pavlov furthered his experimental findings by testing additional variables.

One variable he tested was how far apart, in time, the bell and the food needed to be presented for the association to be learned.

This phenomenon is known as temporal contiguity, and basically states that if the time between the unconditioned stimulus, the bell, and the conditioned stimulus, the food, is presented too far apart, then the learned behavior will not be acquired.

Another variable tested was experimental extinction. This is tested after the initial experiment, when the bell is already associated with the food.

In extinction, or the bell, is presented over and over again without the food. Over time, the connection between the bell and the food will wane, and the saliva produced will lessen until it disappears. This means the bell is no longer conditioned and is considered extinguished.

However, this response is not completely lost. Pavlov tested the idea of spontaneous recovery. This occurs after a rest period, during which the conditioned response can reappear, regardless of whether it was extinguished. This shows that the learned association can remain despite fading over time.

Pavlov also found that stimuli similar to the unconditioned stimulus, the bell, can elicit a similar salivation response. This is known as generalization. So, if Pavlov presented a buzzer, the dog would salivate when it heard it because the sound was similar.

Classical or Pavlovian Conditioning is a theory that claims different learning behaviors can be acquired through an association between a naturally occurring stimulus and an environmental stimulus.

Pavlov had initially hesitated to study psychology because it lacked definitive answers. Through his experiments, Pavlov fundamentally changed the field of psychology by shifting it from a subjective study of the mind to the creation of methods of experimental, objective science. His ability to create and observe a measurable response underpins much of modern psychological research.

Pavlov’s ideas echo in modern-day psychological practices. Modern therapy techniques used to treat extreme phobias, like exposure therapy and systematic desensitization, use techniques of Pavlovian conditioning to lessen the anxiety responses by introducing relaxation techniques or repeated exposure.

Additionally, classical conditioning is employed in therapeutic techniques for treating maladaptive behaviors. These behaviors are typically based on substance abuse.

This type of therapy pairs something like alcohol with something unpleasant, like a nausea-inducing drug. This links alcohol and illness, making the patient less likely to continue alcohol abuse.

Pavlov was the first to scientifically describe this idea, but behaviorists took the data found by Pavlov and used it to further develop the theories of behavioral conditioning.

The most notable of these is the “Little Albert Experiment,” which involved pairing a neutral, harmless stimulus, a white rat, with a loud, scary noise.

Albert, a human infant, was exposed to the rat’s noise and developed a fear of the white rat. It was found that Little Albert’s brain generalized anything resembling something white and fluffy as scary, and proved that fear is learned by environmental factors rather than the unconscious.

The ideas of conditioning can be found in all parts of the human body. The “Garcia Effect,” or taste aversion, explains that falling ill after eating a specific food can create a lifelong aversion to that food. This is a survival mechanism conditioned into your body that associates specific foods with illness, regardless of whether those foods actually caused the illness.

Classical conditioning can also be seen in our everyday lives. Brands market products using unconditioned stimuli, such as catchy songs, specific colors, beautiful backdrops, and attractive people, to elicit a conditioned response to the brand.

It’s also used in educational capacities. Many people use rote memorization techniques, such as flashcards, to associate a question with a specific answer. The goal is to make the answer an innate response.

Additionally, the idea of Operant Conditioning, discovered by B.F. Skinner was heavily inspired by the ideas of classical conditioning. Operant conditioning is similar to Pavlovian conditioning but focuses on studying behavior through the use of rewards and punishments.

Skinner found that reinforcement or punishment of behavior can be used to shape and encourage desired behaviors.

Operant conditioning and classical conditioning differ because classical conditioning is a passive, automatic form of learning, whereas operant conditioning shows the consequences of active, voluntary behavior.

There are some critiques of Pavlov’s theory of classical conditioning.

Because all of Pavlov’s work was done in a controlled environment, it raises questions about whether the findings were applicable in everyday life.

Additionally, there is a question about the variables’ lack of complexity. Every tested response was an involuntary reflection, so there are questions about how it can accurately explain voluntary responses.

The research conducted by Ivan Pavlov is considered the foundation of behavioral psychology. His research on classical conditioning revolutionized the field of psychology and helped shape our understanding of how the mind works.