Ivan Pavlov
Ivan Petróvich Pávlov (from Russian): 
Петрович Павлов (?·i)[chuckles]Ivan Petróvich Pávlov]; Rizan, September 14,Jul./ 26 September 1849Greg.-Lingened, February 27, 1936) was a Russian physiologist, celebrating for having formulated the classic condition (also called Pávlov Dog or Pavlovian Dog).
He was awarded the Nobel Prize in Physiology or Medicine in 1904 "in recognition of his work on the physiology of digestion, through which knowledge about vital aspects of its functioning have been transformed and expanded."
Biography
He was the son of Pyotr Dmitrievich Pavlov (1823-1899), a priest of the Russian Orthodox Church, and Varvara Ivanovna Uspenskaya (1826-1890). He began studying theology, but gave it up to start medicine and chemistry at the University of Saint Petersburg, being his main teacher Vladimir Béjterev. After completing his doctorate in 1883, he furthered his studies in Germany, where he specialized in intestinal physiology and in the functioning of the circulatory system, under the direction of Ludwid and Haidenheim.
In 1890, he was appointed professor of physiology at the Imperial Medical Academy and appointed head of the Department of Physiology at the Institute of Experimental Medicine in Saint Petersburg. In the following decade he focused his work on the investigation of the digestive system and the study of gastric juices. The scientist dedicated more than 10 years to learning how to make holes in the intestinal tract. It was a very complicated operation, since the gastric juice when leaving the intestine corroded the tissues of this and those of the abdominal wall. Pavlov's technique was based on introducing a metal tube through a small incision. It was essential to skillfully suture the skin and mucous membrane and close the cannula outlet with a stopper. In this way he was able to obtain gastric juice from any part of the intestinal tract, from the salivary glands to the large intestine, work for which he won the Nobel Prize in Physiology or Medicine in 1904, thus becoming the first Russian to receive this distinction. The results of Pavlov's research were published in 1897 in the book The Work of the Digestive Glands.
Pavlov is known above all for formulating the law of conditional reflex which, due to an error in the translation of his work into English, was called «conditioned reflex», which he developed from 1901 with his assistant Ivan Filippovich Tolochinov, while in the US Edwin Burket Twitmyer made similar observations. Pavlov observed that the salivation of the dogs used in their experiments occurred in the presence of food or the experimenters themselves, and later determined that it could be the result of a psychological activity, which he called a "conditional reflex." This difference between "conditioned" and "conditional" is important, since the term "conditioned" refers to a state, while the term "conditional" refers to a relationship, which is precisely the object of his investigation.
He performed the well-known experiment of sounding a metronome (at 100 beats per minute, although it is popularly believed to have used a bell) just before feeding a dog powdered food, concluding that when the dog he was hungry, he began to salivate as soon as he heard the sound of the metronome (a device that musicians sometimes use to mark the rhythm). Tolochinov, who called the phenomenon "reflection at a distance", reported the first results at the Congress of Natural Sciences in Helsinki in 1903. Later that year, Pavlov gave a detailed presentation of the results at the 14th International Medical Congress in Madrid, where he read their paper under the title The Experimental Psychology and Psychopathology of Animals.
The Russian Civil War and the arrival of the Bolsheviks did not influence his research. Despite not feeling sympathy for the new regime, he suffered no reprisals from the communists. After the October Revolution he was appointed director of the physiology laboratories at the Institute of Experimental Medicine of the USSR Academy of Sciences.
In the 1930s, he rose to prominence again by announcing the principle that the function of human language is the result of a chain of conditioned reflexes that would contain words.
The foundation of behaviorism as such has been criticized by some philosophers and psychologists as a school of psychology that focuses on the interaction between behavior and the environment, and how it can be learned.
In August 1935, the Soviet Union held the World Physiology Congress in Moscow and Leningrad with more than 900 world scientists in attendance. He was named the world's foremost physiologist. He closed the conference with an emotional speech: "My whole life is made up of experiments, our government also experiments, only at a higher level."
On February 27, 1936, Ivan Pavlov died of pneumonia. He is buried in Saint Petersburg.
Pavlov Studies
Pavlov's original observations were simple. If food or certain dilute acids are put in the mouth of a hungry dog, it begins to secrete a stream of saliva from certain glands. This is the salivation reflex, but that's not all. Pavlov observed that the animal also salivated when the food had not yet reached the snout: simply seeing or smelling food elicited a similar response. In addition, the dog salivated at the mere presence of the person who usually brought it food or any other stimulus that systematically announced it. This led Pavlov to develop an experimental method to study the acquisition of new stimulus-response connections. Undoubtedly, those that he had observed in his dogs could not be innate or connatural to this kind of animal, so he concluded that they had to be learned (in his terms, conditional). The first step, when carrying out this experiment, is to familiarize the dog with the experimental situation that he is going to experience, until he shows no signs of disturbance, especially when the harness is put on and left alone in an isolated room.. A small opening or fissure is made in the dog's jaw, next to the duct of one of the salivary glands. Then, a glass tube (cannula) is placed so that the saliva comes out of it at the moment the salivary gland is activated. The saliva ends up in a glass container with graduation marks, to facilitate its quantification.
One of his fundamental texts, Conditioned Reflexes, was published in Spanish in 1929 (Javier Morata, Madrid) with a foreword by Gregorio Marañón and a few words by the author himself for the Spanish edition. A new edition of this text appeared in 1997 (Editorial Morata, Madrid).
Stimulus-response
The magnitude of the responses to the different stimuli can be measured by the total volume or the number of drops secreted in a certain unit of time. From the next room, and through a window, the experimenter can observe the behavior of the dog, applying the stimuli and evaluating the responses. Before starting the experiment, Pavlov measured salivary reactions to food in the muzzle, which was considerable, while very little salivated under sound stimulation. Next, he began the conditioning tests. He sounded the metronome (neutral stimulus), and immediately thereafter presented food to the animal (unconditional stimulus), with a very short interval. He repeated the relationship between this pair of stimuli many times over several weeks, always when the dog was hungry. Then, after several days, he played only the metronome, and the salivary response came when the sound was heard, despite the fact that no food was presented.
A conditional relationship had been established between the salivary response and the sound that did not originally elicit salivation. It is then said that the salivation of the dog before food is an unconditional response; Salivation after hearing the bell is a conditional response that depends on the relationship that has existed in the subject's history between the sound and the food. The metronome sound stimulus that was originally neutral now functions as a conditional stimulus. This conditional stimulus (sound) works for the subject with that story as a signal that the unconditional stimulus (food) is about to appear.
Finally, the strengthening of the association between an unconditional stimulus and the conditional one was called reinforcement. Reinforcement is an event that increases the probability that a given response will occur to certain stimuli. The definition of classical or responsive conditioning is the formation (or reinforcement) of an association between an originally neutral stimulus and a response (usually a reflex or glandular secretion, as in the case of salivation). The principles of conditioning respondent are used, among others, for the acquisition of habits such as sphincter control. Stimuli can be classified into sensory, proprioceptive, and verbal.
First signal system
This is how he called the relationship by which an association is established in the central nervous system, especially in the brain, for example, between a sound, with the possible food: the sound (or another substitute stimulus) works as a sign. Pavlov considered that most animals are governed by a "thought" based on this system of reflex substitutions, a first system of signals.
Second signal system
But, unlike other authors, Pavlov considered that many "human behaviors" are more complex than a system of simple conditional reflexes in a linear "stimulus/response" model. In Homo sapiens, Pávlov considered that a qualitative leap was produced with respect to the first signal system; In humans, the issue is no longer restricted to conditional reflexes or stimuli that function as a direct substitute for reality. The complexity of human psychological functions facilitates a second system of signals that is verbal or symbolic language. In this the substitutions from the stimuli seem to be infinite and, nevertheless, highly ordered (logical). To a large extent, Pávlov postulates such a capacity of the second system of signals because he considers that in the human being there is a capacity for self-conditioning (learning directed by oneself) that, although it seems contradictory, is liberating: the human being can react to stimuli that he itself is generating and that it can transmit (see information).
The preeminently experimental psychology of Pavlov and his epigones is called reflexology, which is confusing for some people, who confuse it with reflexogen therapy, a form of therapy sometimes called "reflexology."
Other investigations
Pavlov has influenced his country, during the XX century, in a decisive way over other important Psychology researchers: Lúriya, Leontiev, Vygotsky, Bejterev, Shaunyan, etc. Outside of Russia, Watson incorporated Pavlovian terminology and concepts into his own work. Some of the parts of Pavlov's work that have generally remained ignored consisted of the systematic variations that he introduced into his experiments.
For example, he showed that the optimal interval between the presentation of the conditional stimulus and the unconditional stimulus to promote learning (ie, the presentation of a conditional response) is 0.5 seconds. Longer or shorter intervals between stimuli require more trials for learning to occur, and responses are often weaker.
Similarly, he showed that the order in the sequence of stimulus presentation was crucial. If he tried to achieve the establishment of new conditional relationships by first presenting the unconditional stimulus and then the neutral (which was intended to function as a conditional), learning did not occur.
He also showed that not all the relationships between stimuli generated new responses, because in the case of reflexes, such as the patellar (stretching the leg before a light blow in a certain region of the knee), one did not learn to respond to the stimuli that they "announced" the coup (Millenson, 1974).
Pávlov also studied phenomena such as "generalization", that is, the presentation of conditional responses to stimuli similar to the original conditional stimulus. He found that, unlike unconditional (unlearned) reflexes, the magnitude of the response was not directly proportional to the intensity of the stimuli (i.e., the greater the intensity of the stimulus, within limits, the greater the magnitude of the stimulus). the response), but in the case of conditional relationships, the greater magnitude in the response depends on how similar the stimulus presented is to the original conditional stimulus. This results in a gradation (sometimes called a gradient), such that stimuli of slightly less or greater intensity relative to the original conditioned stimulus elicit conditional responses of greater magnitude than do stimuli of greater intensity than the conditioned stimulus., although the greatest magnitude of the conditioned response is always given to the original conditional stimulus (Millenson, 1974).
On the other hand, Pavlov also studied «stimulus discrimination», that is, both the subject learns to behave differently when faced with different stimuli that announce other stimuli. In one of the best-known examples, he managed to get his subjects to salivate at circles that announced the presence of food and to behave in a species-typical manner when faced with aversive stimuli, such as electric shocks, in the presence of ellipses. That is, the dogs jumped, howled, tensed, etc., before ellipses, but salivated before circles, if in their history, each of these stimuli was consistently presented as an "announcement" of the corresponding unconditional stimuli (electric shocks before the ellipses and food before circles) (Millenson, 1974).
Pavlov studied many other learnings, both in animals and in humans, including what was called the induction of "experimental neurosis," and practically founded the experimental study of behavior considered "abnormal" or "psychopathological," as well as his counterpart to modify various undesirable behaviors, including phobias, tics, and "neurotic" behaviors, so that subjects learn adaptive behaviors and eliminate anxiety and other undesirable reactions (Sandler & Davidson, 1980).
Pavlov is an example of how great scientific discoveries often include a combination of "accidental" events and an observation of them by people with sufficient training not to consider them not as failures or exceptions, but as objects of interest in their own right. themselves, which are a function of their relationship with one or more independent variables.
One of these cases, according to Sandler and Davidson (1980), occurred when a strong flood endangered the integrity of the dogs that Pavlov experimented with, as the basement where their cages were located began to fill up. of water. Pavlov and some of his assistants went to the laboratory despite the environmental conditions and brought the dogs to safety. The fact may not have been disclosed, but it happened that, when an attempt was made to reinstall the dogs in the basement, several aspects of their behavior presented "strange" variations. Although they had behaved docilely before the investigators, now they were hostile; In addition, they stopped eating regularly, withdrew, stopped having sex, and often howled as if there were other dogs or people, even though they weren't there. This behavior could be considered "neurotic." On the other hand, said behavior lessened when the dogs were transferred to environments very different from the basement. Pavlov reasoned, in his terms, that the sudden and intense presence of strong aversive stimuli had caused a conditioning to the stimuli that were present in the basement.
After reflecting on this, he instituted a systematic way to reverse the effects of that conditioning. He started by leaving the dogs in an environment quite different from the basement, and when the dogs behaved in a "normal" way, he began to carefully and gradually replace different stimuli from the new environment (subtraction fading) with ones that had been present. in the basement (add fade). In the end, the dogs were able to return to the basement, while their behavior remained completely "normal."
Pavlov also noted that he could induce "neurotic" behaviors by presenting very difficult discriminations. In the aforementioned case of the circle (to which food was presented) and the ellipse (to which an electric shock was presented), the subjects behaved appropriately towards each after a series of trials (say, for example, 50 trials). However, as the circle and ellipse became more and more similar, there came a point at which the subjects behaved in a manner similar to that of the dogs that had undergone the aversive experience in the basement. But by restoring the original conditions for the circle and the ellipse, the subjects gradually returned to behaving in the appropriate way for each, even though the number of trials required was about twice the original (say, 100 trials). As the subjects adequately discriminated the circle of the ellipse, their behavior outside the experimental situation also changed from "neurotic" to "normal."
Pávlov's reasoning was of the type: if neurotic behavior could be induced under certain conditions (experimental neurosis), it can also be modified if the independent variables of which it is a function are changed. Pavlov thus inaugurated what can be considered experimental behavior modification in Russia.
Both the scientific study of "abnormal" behavior and its modification were greatly influenced by Pavlov's type of findings and reasoning.
Eponymy
- The lunar crater Pavlov bears this name in his memory.
- The asteroid (1007) Pawlowia bears this name in his memory.
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