Pavlov's experiments are interesting. Who is she, "Pavlov's Dog" - a heroine or a victim

- the fate of the "martyrs of science" did not bypass the dogs. Moreover, it is the dog with its trusting and devoted canine friendship for a person that causes special sympathy here. From science quickly migrated to folklore, art and everyday life, the expression "Pavlov's dog" has not without reason become a symbol of the silent victim of cruel and inhuman experiments.

There are many legends about this most authoritative scientist. Rumor has it that Ivan Petrovich Pavlov tortured not only his experimental dogs, but also all his colleagues and employees, because he was very meticulous and demanding in relation to everything that happened.

Throwing jokes aside, recall the merits of Pavlov: it was he who laid the foundation in the doctrine of higher nervous activity, the largest physiological school and received the Nobel Prize in medicine and physiology "for his work on the physiology of digestion."

Unhappy, salivating, with cut esophagus and fistulas - what to do if the mere mention of Pavlov and his dogs unanimously evokes such gloomy associations in a simple layman, and the image of the dearest Ivan Petrovich is "stained" with such a persistent silent condemnation from compassionate cooks. The greatest physiologist was neither a sadist nor a flayer, although his experimental subjects could well be called heroes, victims, and even, in a sense, the scientist's employees (subordinates, of course). At the same time, aimless and sophisticated mockery of the innocent should not be confused with scientific work Pavlova. The results of the experiments are used to improve the quality and save the lives of those very inhabitants, who with such vain reproach look at the immortal works of the scientist.

By the way, Pavlov was not the first to slaughter dogs. "Friends of Man" was sent to the slaughter by Hippocrates - for the sake of science, of course, not just like that. Although these experiences of the "father of medicine" were not included in school textbooks. But Pavlov's experiments on the study of conditioned reflex activity were not only included in textbooks, but in most cases they were clearly illustrated. Now every schoolchild knows how strongly dogs "attach" to certain nutritional conditions that usually accompanied their feeding.

I.P. Pavlov was not heartless at all. On the contrary, he felt natural with dogs and did everything possible, wanting to minimize them. He not only treated the animals after the experiments, but also did not leave "pensioners" to the mercy of fate. Even during the period of severe flooding in Leningrad, the dogs were not abandoned. So, aged dogs lived “under the wing” of the scientist for a long time, receiving their well-deserved rations, and many of them died of natural causes.

The dogs of the scientist and trusted him. And Ivan Petrovich also had great respect for dogs. As a sign of immense recognition and respect, Pavlov even ordered - "Unknown dog from grateful mankind", which now stands in St. Petersburg near the building of the Institute of Experimental Medicine. This monument is the hand of the sculptor I.F. Bespalov in 1935 worthily perpetuates the memory of the scientist's selfless colleagues.

Ivan Pavlov. Probably everyone has heard about this scientist. Some, not only know this name, but are also well acquainted with his scientific activities. After all, his achievements touched practical activities both physicians and teachers with psychologists. In addition, many philosophers are actively studying his legacy. Yet, what was so revolutionary that Pavlov brought to science with his dog? Read on for this and more.

A little biography

The creative path of an outstanding scientist began in a small laboratory in St. Petersburg at the clinic of another outstanding scientist, Botkin. It was here that Pavlov set his first and formulated the concept of nervism, fundamental for all his subsequent activities. By this category he understood the influence of the central nervous system throughout the life of a living organism.

The dissertation of the scientist for the degree of Doctor of Medical Sciences was devoted to the topic of the nerve discovered by him. This nerve affects the heart. His work in this area has advanced the study of the heart and self-regulation. blood pressure. These little-known achievements, while significant discoveries, were only the beginning of a journey along which other innovative ideas were developed.

Dog

One of the most interesting scientific questions in terms of human physiology has always been the question of digestion. Scientists have long tried to figure out how this process proceeds, which causes food to break down into small particles and be absorbed by the body.

By the time Pavlov began to study this issue, scientists had already made a number of discoveries, but much remained unexplored. The problem was the lack effective method study. It was almost impossible to follow the full course of digestion in a living organism. The most popular were experiments with animals, during which a tube was attached to the pancreas, which made it possible to monitor the separation of bile. However, this experience provided very little information. Attempts were also made to sew an animal with a tube into the pancreatic duct, but such operations were accompanied by inflammatory processes, and scientists have abandoned them.

Both methods did not satisfy Pavlov in any way. He wanted to get information about the work of not one separate body, but the entire system as a whole with all its constituent elements. The scientist also wanted to find out the relationship between body reactions and conditions. environment. That is why he began to study the most common reactions of the animal to external stimuli.

In 1879, Pavlov performed his famous operation, during which he made a hole in the pancreas of a dog without disturbing its functioning. The dog remained alive and healthy, and the scientist had the opportunity to observe the full cycle of the digestion process.
Subsequently, other innovative operations were carried out in the laboratory of the scientist, during which similar holes (fistulas) were superimposed on the stomach and intestines of the animal. The ducts of the salivary glands of the animal were also brought out.

By numerous successful experiments, Pavlov proved great importance for the process of digestion of the nervous system. The direct relationship between the two systems was clearly demonstrated.

Pavlov until the end of his life was full of energy and enthusiasm. His desire for knowledge of the unknown remained with him until his very last days.

The text is dedicated to the dogs that participated in the experiments of the Russian scientist IP Pavlov. I will talk about where the famous expression "Pavlov's dog" came from and what lies behind it.

What is Pavlov's dog

Ivan Petrovich Pavlov was a Russian scientist from Ryazan, a member of the Imperial St. Petersburg Academy of Sciences. He was born at the end of the 19th century and devoted his research to the study of the higher nervous activity of man.

His merit was the creation, practically from scratch, of the doctrine of the physiology of digestion and the separation of conditioned and unconditioned reflexes. His research was highly recognized at the international level - in 1904 he received the Nobel Prize in Medicine, becoming the first Russian Nobel laureate.

In his experiments, the scientist used animals - dogs. For the sake of scientific purposes, animals were subjected to operations, many of which cost their lives. Ivan Petrovich was not cruel and made every effort to reduce the suffering of animals.

He not only put his experiments on them, but also treated them after that. Many animals grew old around him and died of natural causes, having lived full life after surgical interventions.

Going to experiments that entail the inevitable death of pets, Pavlov experienced real suffering. According to contemporaries, the dogs loved the scientist and went to the operating room themselves, as if they understood the importance of research.

In the memorial museum-estate of academician I. P. Pavlov in Ryazan there is an exhibit - a stuffed dog in an installation for an experiment on the study of conditioned reflexes. This animal collective image all participants scientific experiments Pavlova.

The House of Science on the territory of the museum presents an exposition that details the progress of research.

The essence of experiments and experiments

Pavlov's experiments initially concerned exclusively the work digestive tract. He performed an operation, thanks to which he could observe the process of secretion of gastric juice in animals at the time of feeding.

The complexity of this work was that the ingress of gastric juice on the tissues abdominal cavity led to their digestion and the animals died. Pavlov spent a decade overcoming this problem and obtaining a fistula - a sealed opening in the gastrointestinal tract.

Later, the scientist noticed the reaction of the dogs to the sound of the steps of the person who usually feeds them. He saw that animals salivate while waiting for food, before the very moment of feeding.

The scientist thought about the study of reflex activity. The experiments took on a different character. Studied salivation and secretion of gastric juice in connection with external events (a light bulb was lit or a bell sounded).

Development of classical conditioning theory

The study of conditioned reflexes led to the emergence of the theory of conditioning, which consists in the effect of an initially neutral stimulus on the brain.

A neutral stimulus, associated with a stimulus that unconditionally generates a certain reaction, causes the same reaction. These data subsequently had a huge impact on the development of psychology.

In gratitude for the help and sacrifices made by the four-legged for the sake of science, Pavlov ordered and erected a monument to an unknown dog in the square of the building of the Institute of Experimental Medicine in St. Petersburg on Aptekarsky Island.

On four sides, the pedestal is decorated with bas-reliefs depicting important aspects dog and human behavior during the experiments. The inscriptions under the bas-reliefs pay tribute to the loyalty, patience and intelligence of the experimental animals.

Throughout the entire path of mankind along the path of science, dogs are their faithful companions. It is they, of all animals, who have the ability to communicate with humans, which puts them at risk of scientific experiments.

Dogs go under the knife or fly into space before people dare to do so. It is possible to preserve humanity in these conditions only by remembering, like I. P. Pavlov, the inadmissibility of cruelty and vain sacrifices.

Experimental work on the study of the mechanisms of formation of conditioned reflexes was carried out in the laboratory of I.P. Pavlov in Koltushi, near St. Petersburg. In order to get rid of the influence of numerous random stimuli interfering with the development of the conditioned reflex, the dogs were worked on in isolated soundproof chambers, in the so-called "Tower of Silence". The experimenter was outside the chamber and watched the dog through a small hole with a special glass system that prevented the animal from seeing the experimenter. In addition, the dog was fixed in a special machine, limiting the possibility of its unnecessary movements.

Prior to the start of work, the dog underwent an operation in which one of the ducts of the salivary glands was brought out to the cheek. After this operation, part of the saliva did not enter the oral cavity, but was brought out through the fistula, which made it possible to record the beginning of salivation, the quantity and quality of saliva released. There were a number of devices in the cell, with the help of which it was possible to give the dog various signals: sound (bells, metronome beats, ratchet crackling, etc.), light (bulb flashes, projection different figures on the screen, etc.). With the help of special devices, touches of different frequencies, various temperature irritations, etc. could be applied to the dog's skin. Automatically, the dog was given a feeder with additional food, usually in the form of meat-and-sugar powder.

The classic "Pavlovian" experiment on the development of conditioned reflexes was carried out as follows. The dog, located in the chamber and in the machine, was automatically fed food (unconditioned stimulus), then the appearance of food began to be preceded by a “conditioned stimulus”, or “conditioned signal”, in the form of a call, a flash of a light bulb, or the sound of a metronome. The reaction of the dog to the unconditioned stimulus in the form of food is accompanied by an unconditioned reflex separation of saliva. The presentation of an unconditioned stimulus following a conditioned stimulus during an experiment is called "reinforcement". If, during the development of a conditioned reflex, a reinforcement is applied that corresponds to the motivation of the animal (for example, food reinforcement in a hungry animal), then it is called “positive”. It is possible to develop a conditioned reflex with the use of "negative reinforcement" (punishment), that is, such an impact that the animal seeks to avoid. In the experiment, blows are most often used as a negative reinforcement. electric current, causing the animal to run to the safe compartment of the chamber or causing it to have an unconditioned reflex withdrawal of the limb. An example of a negative reinforcer is the action of an air jet directed at the cornea of ​​the eye, causing a blinking reflex.

Pavlov's discoveries. Pavlov managed to show how a conditioned reflex arises in response to various signals and different types and reinforcement conditions. In addition, he found that in the case when the conditioned signal is repeatedly presented without reinforcement, the reflex is attenuated. In this case, the reaction weakens, often becomes irregular, and eventually the conditioned signal ceases to operate. Pavlov also showed the presence of behavioral reactions associated with conditioned reflex reactions. For example, after the conditioned reflex reaction of salivation to the sound of a bell of a certain pitch was developed, it was also possible to evoke it with a bell with a different pitch; in another experiment, salivation was induced by scratching not only a certain place on the paw, but also neighboring areas. In each case, the degree of response to the new stimulus depended on how similar it was to the original stimulus. A call slightly different in pitch, or scratching a place close to the original, resulted in almost the same salivation as the original signals; a call that was very different in height or scratching at a distant site caused the release of a smaller amount of saliva. As it turned out, this effect, called generalization, can be neutralized by reinforcing only the original signal, stopping the reinforcement of the rest. In this case, the animal develops the ability to distinguish: the reaction is fully manifested only to the initial conditioned signal, and to all others it is insignificant or completely absent. Using this technique, Pavlov was able to determine what are the minimum changes in the stimulus that the dog is able to distinguish.

Based on his experiments, Pavlov developed several theories of the work of the cerebral cortex, in particular the theory of excitation and inhibition - cortical states characterized by increased and decreased activity. He suggested that inhibition, spilling over the cortex, is the cause of such a phenomenon as the attenuation of the conditioned reflex. Pavlov believed that sleep is a state in which inhibition completely captures the cerebral cortex. Later work in neurology and psychophysiology showed that the work of the cortex is much more complex than he thought.

Modern ideas. Pavlov applied the term "conditioned reflex" to any individually acquired types of behavior. The concept of a signal stimulus, however, does not explain all types of learning. The term "conditioned reflex" is now used in a narrower sense, in relation to situations similar to Pavlov's original experiments, for example, the work of the autonomic nervous system, managing activities glands and smooth muscles. It is also acknowledged that conditioned reflexes widely represented in emotional behavior. The conditioned human reflexes that arise on the basis of the blinking reflex, salivation, sweating, constriction and expansion of the pupils, contraction and relaxation of the smooth muscles of the walls are well studied. blood vessels. Nevertheless, there is a significant area of ​​acquired behavior that is formed on the basis of other mechanisms. So, it turned out that, unlike a conditioned reflex, in which the appearance of a reaction to a conditioned signal is always preceded by its reinforcement, the animal can form a reaction that was reinforced in the past after its manifestation (this mechanism was called operant conditioning).

There is no need to prove that IP Pavlov was an outstanding scientist. For my long life(1849-1936) he achieved great success thanks to great diligence, purposeful work, a sharp eye, theoretical clarity, exceptionally skillful experimentation and, last but not least, a masterful presentation of the results of his research and thoughts. He began his scientific activity in the field of physiology, the science of the processes occurring in a healthy human body such as circulation, temperature regulation, digestion and excretion. Knowledge acquired in this special field of science is absolutely necessary for mastering the art of healing.

Modern scientific research constantly asks nature questions. For example, what happens in the body when it is in conditions of very low atmospheric pressure and limited oxygen, as it happens when climbing a high mountain or in an airplane? The answer to this question can be obtained on earth. To do this, use the camera low pressure(pressure chamber), from which air is gradually pumped out, thereby lowering the pressure. Since it is impossible to say in advance whether such experiments will not be dangerous for humans, they are usually carried out first on animals. To some extent, they answer the questions posed in the experiment, in our example - a change in the work of the heart, rapid breathing and other carefully recorded phenomena. All these processes cannot be studied simultaneously, and therefore particular problems are singled out.

While still a young physiologist, Pavlov dealt with issues of digestion, or rather part of this problem - the causes of secretion (excretion) of saliva into the oral cavity and gastric juice into the stomach. What causes this secretion?

It was suggested that the glandular cells of the walls of the stomach begin to secrete juice when they are touched by swallowed and chewed pieces of food. Having performed two operations on dogs, Pavlov proved that this explanation is incorrect. He cut the esophagus and brought the end of the segment coming from the oral cavity into a cut in the skin on the neck; as a result, each piece swallowed by the animal fell out. In addition, Pavlov put a fistula on the stomach. A fistula is a tube that is inserted at one end into the wall of the stomach, and the other is brought to the surface of the abdomen; the juice formed in the stomach flows drop by drop through the fistula into a special vessel. These studies have shown that with each meal, the dog produces gastric juice, although no food enters the stomach. What is happening is clearly shown in Fig. 6.

It turns out that the secretion of juice in the stomach can only be caused by nervous excitement. However, there are no direct nerve pathways that would lead from the mouth to the stomach, and there are only those that go from the mouth to the brain and already from the brain to the stomach.

Even before Pavlov, another outstanding Russian physiologist, Ivan Mikhailovich Sechenov (1829-1905), reduced everything that happens in the body to reflexes. The nerve pathways of the reflex form the so-called reflex arc, which consists of a sensitive branch that transmits to the brain everything that the sense organs perceive (of course, this is a purely biological, and not physical transmission), and a motor branch that departs from the brain and goes to the "working organs", that is, muscles and glands.

Pavlov paid the main attention to the activity of the salivary glands. It is known that a dog with sand in its mouth secretes more saliva than when eating. And people only at the sight delicious dish salivation may begin. This is evidenced by the well-known expression "drooling." At the end of the last century, there was a "scientific" opinion that bodily secretion is caused by non-corporeal joy caused by received or expected pleasure. It was believed that something independent of the body and called the soul can mysteriously influence the functioning of organs. At the same time, two points remained unclear: firstly, whether some kind of joy, pleasure, pleasant taste, desire, expectation, or even a thought really was the root cause and, secondly, how this action manifests itself in each specific case.

Physiological research helped Pavlov understand the value of accurate measurements. He set out to study as fully as possible the secretion of saliva, the amount of which varied greatly depending on the circumstances. The experiment that he set up reveals in him a very skillful master of operations on animals. To measure the amount of saliva produced, he had to put a fistula on the parotid salivary gland. The operation was complicated by the fact that the tube had to fit exactly into the excretory duct of the gland. Subsequent researchers did not immediately succeed in repeating Pavlov's experiment. They had to first learn the intricacies of operating. When Pavlov gave the dog thus prepared small pieces of meat, saliva dripped from the fistula into a measuring vessel placed under it.

In other experiments, Pavlov combined feeding with a sound stimulus - a bell or a buzzer. Normally, exposure to the dog's hearing does not cause salivation. From this point of view, noise is an indifferent stimulus. But everything changes as soon as this exposure is repeatedly repeated before feeding. In contrast to noise, irritation of the oral cavity in all cases causes the release of saliva. This is an innate reflex, unlike those that cause secretion only when certain conditions. Pavlov called reflexes of the first type unconditioned, and the second - conditional.

The installation with which IP Pavlov worked is shown in fig. 7 in a highly simplified form. The experimental dog was fixed with straps in a special machine, a bowl was placed in front of it, and there was a bell on the front of the frame. As soon as it rings, the animal receives a small portion of food. After several repetitions of this procedure, saliva is released immediately after the call, including when the acoustic signal is not reinforced by food. In these cases, secretion is evoked by a conditioned reflex that has developed in the animal as a result of repeated combination of a sound stimulus with food reinforcement.

But I.P. Pavlov was looking for scientific explanation the facts they discovered. He was interested in how irritation of the organ of hearing (or vision), which is not associated with digestion, affects the glands of the mouth. The significance of the theory developed by Pavlov, about which most of my readers have already heard, can only be correctly assessed in view of the worldviews and social relations that prevailed in his time.

As before, there were people (there was such a person among Pavlov's employees) who, as we have already said, believed that everything was explained by the action of spiritual forces. Pavlov, listening to them, only shook his head. He later wrote: “Among my laboratory staff, one young doctor stood out. One could see in him a living mind, understanding the joys and triumph of investigating thought. Imagine my astonishment when this true friend laboratory showed true and deep indignation when he first heard about our plans to investigate the mental activity of the dog in the same laboratory and by the same means that we have hitherto used to solve various physiological problems. None of our beliefs had an effect on him, he promised and wished us all sorts of failures. And, as one could understand, all this was because in his eyes that lofty and peculiar thing that he believed in spiritual world man and higher animals, not only could not be fruitfully investigated, but directly, as it were, offended by the rudeness of actions in our physiological laboratories.

Here I must draw the reader's attention to scientific facts, which are often omitted in numerous descriptions of Pavlov's main researches. We will talk about the brain, the functions and structure of which, until the last quarter of the last century, did not yet have a clear idea.

In the early 1970s, brain research showed that certain well-defined areas of the cerebral cortex control certain areas of the body, such as the muscles of the face, arm or leg. If, as a result of a severe head wound, the corresponding part of the brain was damaged, then the hand and only it ceased to function, and not any other part of the body. If another part of the brain was damaged, the activity of any sense organ was disturbed: the wounded man was blind or deaf. Such areas of the brain are called centers; from them, as it is now absolutely undeniably proven, there are nerve pathways respectively to the ear, tongue or salivary glands. Although the doctrine of centers was also new to the young Pavlov, in his writings the existence of these centers is already taken for granted. Now we know that the doctrine of the centers is not as comprehensive as it was thought in those days; however, we will not dwell on this in detail.

Pavlov was a physiologist-materialist. He understood that the explanation of the phenomena he observed during the release of saliva should be sought in real-life processes that can be detected by precise research. In accordance with the doctrine of the centers, he suggested that with each impact of an irritant on the taste buds of the mouth, the corresponding center is excited, this excitation is transmitted in a certain way to the second center that controls the activity of the salivary gland, which brings the organ subordinate to it into an active state. This explains the mechanism of the unconditioned reflex.

If, simultaneously with the excitation of the center that controls hearing, we repeatedly excite the center that controls taste sensations, then a connection is established between these centers, which Pavlov called temporary. From now on, any irritation of the first center leads to irritation of the second, and that, in turn, to the release of saliva.

It is very important to note that this relationship is temporary. During the development of a conditioned salivary reflex, for example, to light light bulb, the experimental animal receives food after each activation of the optical signal. Experts say in such cases about the reinforcement of the conditioned reflex by the unconditioned one. The conditioned reflex will work even if you stop reinforcing it, that is, turn on the light stimulus and not give food. But if the conditioned stimulus is repeatedly applied without reinforcement, then the number of droplets of saliva released from experience to experience will decrease until the salivation eventually stops altogether. The conditioned reflex will fade away.

What does it mean? It can be assumed that the animal has forgotten about the connection between the stimulus and the receipt of food. This assumption does not strike us as improbable. It is not uncommon to hear one person tell another that they have forgotten something, such as the price of a book whose title they remember but cannot relate to the price. Between the name and the price there was a temporary connection, which disappeared. This disappearance is comparable to the fading of a poorly fixed photograph, in which, after a long time, nothing can be made out. It would seem that forgetting the appearance of a certain person or building can be explained in exactly the same way. It seems that the previously perceived image - not only reflected, but also imprinted in the brain - disappears.

Pavlov, on the other hand, proved undeniably that sufficiently firmly imprinted perceptions, as well as the relationship between them, are not forgotten; the analogy with either the slowly “fading” photograph or the final disappearance of the image is inapplicable to them. If the conditioned reflex was reinforced only a few times, it fades quickly. Almost as much effort has to be expended on its restoration as in its primary development.

The situation is different when the conditioned stimulus - a sound or light signal - was reinforced repeatedly.

In this case, the conditioned reflex fades away slowly. If he is then reinforced again, even after a long pause, he recovers surprisingly quickly; this means that such a conditioned reflex is not completely “forgotten”.

Brilliantly and boldly, I. P. Pavlov suggested that in such cases the temporary connection between the stimuli causing the reflex (sound and irritation of the taste buds) does not disappear, just the conditioned reflex was inhibited. Consequently, any forgetting of sufficiently firmly fixed temporal connections is explained by inhibition. The excitation transmitted from one center to another is gradually inhibited, which eventually leads to a complete stop. this process. To this it should be added that excitation and inhibition in various combinations are the processes on which all higher nervous activity is based. Modern research bring more and more evidence to this.

To illustrate what forgetting is, let's take a convincing example from people's lives. Let's ask forty-year-old men the names of their classmates in graduation class with whom they studied long years. IN best case they will remember a few names and say that they have forgotten the names of the rest. After 25 years, already in old age, the memories of these people will become much more complete, they will name more names than before. The content of their memory did not "fade", did not disappear, it was only muted by something else.

In the practice of studying conditioned reflexes, it often happened that some extraordinary stimulus, for example, the crash of a door suddenly slamming shut, stopped the action of the conditioned reflex. The saliva that had been secreted before stopped dripping. This phenomenon can be explained by assuming that a certain third center was strongly excited and this excitation led to the suppression of the conditioned reflex. In the same way, in forty-year-old men, youthful memories are inhibited, and not “forgotten” in the usual sense of the word, since the brain is in its most complete flowering creativity operates at full load and ratios and connections that do not currently play a special role are muted. All especially exciting events slow down those nervous processes that are in no way connected with them. Pavlov wrote on this occasion: "Before the urgent demand of the external situation, other current activities must temporarily recede."

The study of conditioned reflexes helps to understand the process of forgetting. Needless to say, much more important is what this research method has contributed to understanding learning. In accordance with what we have already learned, we can say that learning consists in the formation of temporary connections. Is this true for any kind of learning?

The answer can only be negative. However, there are numerous learning processes in people's lives that can indeed be reduced to temporal connections. This refers to memorizing words or turning on a light with a switch, remembering the time a train leaves or which shelf a book is on. This type of learning can also take place in animals. In this sense, we can say that the dog also understands the meaning of words. Following the “sit” command, she actually sits on her hind legs. Her understanding is based on the temporal relationship between the sound signal and the rewarded behavior. The reward serves as nothing more than a reinforcement of the acoustic signal. Therefore, dog training is based to a large extent on the teachings of Pavlov, who convincingly showed us how this understanding and training is carried out.

Conditioned reflexes are formed already in the first days of life. Everything looks as if a newborn puppy, sucking mother's milk, reacts to the smell, the action of which is innate for him. sucking is unconditioned reflex. One Soviet scientist, using a well-thought-out experiment, showed that the first conditioned reflexes are formed in a puppy immediately after birth. Puppies that are born are first cleaned by their mother, who licks them. Then, crawling around her, they look for and find the nipples. To study the behavior of the puppies, their mother had her nipples, tail, and paws washed and peppermint shortly before birth; this smell was the first thing that blind puppies perceived in their lives. After the first suckling of the mother, they fell asleep. They were placed in a box for 80 minutes and then placed one by one on the table. Here, a piece of wool was brought to the nose of each puppy, smelling the same as their mother, mint. The little creature crawled forward and sometimes even tried to suck on wool (Fig. 8). Soon the experiment was repeated, this time the pieces of wool smelled differently than the mother, for example, menthol oil. The puppies, sensing the smell, turned away and crawled back (Fig. 8, below).

The conditioned reflex plays a big role in the life of both animals and people. Ignoring the sudden red light of a decorative street lamp, the driver drives past without hesitation. But, if the red light of the traffic light lights up, it immediately slows down. Using the above terms, we can say that when a red traffic light appears, a braking reflex is triggered.

Perhaps one of the readers might think that what happens when a driver perceives a color signal is thought process. But then he must admit that thinking (even in its simplest form) could only be discussed if the driver, before braking, took into account the likelihood of an accident or paying a traffic ticket. In fact, of course, he did not think about either of these at the moment of braking. We have not yet discussed what should be understood by the word "thought." In any case, the action we have just been talking about is much easier than that what does an engineer designing a turbine for a power plant do. The processes taking place in his brain cannot be imagined as a simple chain of conditioned reflexes. The human mind is much more complex. Very complex and relatively simple processes that mutually influence each other. Therefore, it can be argued that conditioned reflexes play a subordinate, particular role in our thinking.