Pavlov's Dog Pavlov's Dog Ivan Petrovich Pavlov (1849-1936) Who was Ivan Pavlov? The Russian scientist Ivan Petrovich Pavlov was born in 1849 in Ryazan, where his father worked as a village priest. In 1870 Ivan Pavlov abandoned the religious career for which he had been preparing, and instead went into science. There he had a great impact on the field of physiology by studying the mechanisms underlying the digestive system in mammals. For his original work in this field of research, Pavlov was awarded the Nobel Prize in Physiology or Medicine in 1904. By then he had turned to studying the laws on the formation of conditioned reflexes, a topic on which he worked until his death in 1936. His discoveries in this field paved the way for an objective science of behavior. Pavlov's drooling dogs While Ivan Pavlov worked to unveil the secrets of the digestive system, he also studied what signals triggered related phenomena, such as the secretion of saliva. When a dog encounters food, saliva starts to pour from the salivary glands located in the back of its oral cavity.

This saliva is needed in order to make the food easier to swallow. The fluid also contains enzymes that break down certain compounds in the food. In humans, for example, saliva contains the enzyme amylase, an effective processor of starch. Pavlov became interested in studying reflexes when he saw that the dogs drooled without the proper stimulus. Although no food was in sight, their saliva still dribbled. It turned out that the dogs were reacting to lab coats. Every time the dogs were served food, the person who served the food was wearing a lab coat. Therefore, the dogs reacted as if food was on its way whenever they saw a lab coat. In a series of experiments, Pavlov then tried to figure out how these phenomena were linked. For example, he struck a bell when the dogs were fed. If the bell was sounded in close association with their meal, the dogs learnt to associate the sound of the bell with food. After a while, at the mere sound of the bell, they responded by drooling. Different kinds of reflexes Reflexes make us react in a certain way. When a light beam hits our eyes, our pupils shrink in response to the light stimulus.

And when the doctor taps you below the knee cap, your leg swings out. These reflexes are called unconditioned, or built-in. The body responds in the same fashion every time the stimuli (the light or the tap) is applied. In the same way, dogs drool when they encounter food. Pavlov's discovery was that environmental events that previously had no relation to a given reflex (such as a bell sound) could, through experience, trigger a reflex (salivation). This kind of learnt response is called conditioned reflex, and the process whereby dogs or humans learn to connect a stimulus to a reflex is called conditioning. Animals generally learn to associate stimuli that are relevant to their survival. Food aversion is an example of a natural conditioned reflex. If an animal eats something with a distinctive vanilla taste and then eats a tasteless poison that leads to nausea, the animal will not be particularly eager to eat vanilla-flavoured food the next time. Linking nausea to taste is an evolutionarily successful strategy, since animals that failed to learn their lesson did not last very long. Why were Pavlov's findings given so much acknowledgment?

Pavlov's description on how animals (and humans) can be trained to respond in a certain way to a particular stimulus drew tremendous interest from the time he first presented his results. His work paved the way for a new, more objective method of studying behavior. So-called Pavlovian training has been used in many fields, with anti-phobia treatment as but one example. An important principle in conditioned learning is that an established conditioned response (salivating in the case of the dogs) decreases in intensity if the conditioned stimulus (bell) is repeatedly presented without the unconditioned stimulus (food). This process is called extinction. In order to treat phobias evoked by certain environmental situations, such as heights or crowds, this phenomenon can be used. The patient is first taught a muscle relaxation technique. Then he or she is told , over a period of days, to imagine the fear-producing situation while trying to inhibit the anxiety by relaxation. At the end of the series, the strongest anxiety-provoking situation may be brought to mind without anxiety. This process is called systematic desensitization. Conditioning forms the basis of much of learned human behavior. Nowadays, this knowledge has also been exploited by commercial advertising.

An effective commercial should be able to manipulate the response to a stimulus (like seeing a product's name) which initially does not provoke any feeling. The objective is to train people to make the "false" connection between positive emotions (e.g. happiness or feeling attractive) and the particular brand of consumer goods being advertised. Pavlov's prize Although the first image that comes to mind while mentioning Ivan Pavlov's name is his drooling dogs, he became a Nobel Laureate for his research in a different field. In 1904 he received the Nobel Prize in Physiology or Medicine for his pioneering studies of how the digestive system works. Until Pavlov started to scrutinize this field, our knowledge of how food was digested in the stomach, and what mechanisms were responsible for regulating this, were quite foggy. In order to understand the process, Pavlov developed a new way of monitoring what was happening. He surgically made fistulas in animals' stomachs, which enabled him to study the organs and take samples of body fluids from them while they continued to function normally.

By Lotta Fredholm, Science Journalist First published 15 May 2001 Ivan Pavlov Glossary Ivan Petrovich Pavlov Essentially, only one thing in life is of real interest to us - our psychical experience. Its mechanism, however, was and still is shrouded in profound obscurity - I. P. Pavlov Ivan Pavlov was a Russian scientist most famous for describing the psychological phenomenon referred to as a "conditioned response". Pavlov made a number of other very important discoveries in the realm of physiology, particularly related to digestion. Indeed, it was while studying the secretion of digestive enzymes that he became interested in the integration of the body and the brain. Born to a Russian minister on September 14, 1849, Pavlov grew up in the town of Ryazan. Due to a childhood accident, Ivan was unable to attend school as early as other children, but did get started at age 11. After finishing school he was sent to theological seminary to follow in his father's footsteps, but dropped out in 1870 to enroll at the University of St. Petersburg. It was there that Pavlov became interested in and started his career in physiology.

His first research project, under the tutelage of Elie Cyon, involved investigation of pancreatic nerves, and this work earned him gold medal honors at the university. Pavlov continued his studies at the Military Medical Academy between the years of 1875 and 1879. He finished his dissertation and earned the degree of doctor of medicine in 1883. Pavlov gained the influence of prominent researchers such as Ludwig, Heidenhain, and Bofkin during the next several years, and was named Professor of Pharmacology at St. Petersburg Institute of Experimental Medicine in 1895. Soon after this honor he became Professor of Physiology, and held that position until 1924. Pavlov's first independent work focused on the physiology of the circulation of the blood. He studied the influence of variations in blood volume on blood pressure. He also investigated the nervous control of the heart, and argued that rhythm and strength of cardiac contractions are controlled by four types of nerves. It was during this first independent study that Pavlov used unanesthetized, neurologically intact dogs. This method became the mainstay of Pavlov's methodology.

Pavlov felt that the experimental methods used by many physiologic researchers introduced too many sources of error. In order to understand the true physiological mechanisms of an organ, that organ had to be observed as it functioned as a part of whole body: "I would prefer to remain a pure physiologist, that is, an investigator who studies the functions of separate organs, the conditions of their activity, and the synthesis of their function in the total mechanism as a part or in the whole of the organism; and I am little interested in the ultimate, deep basis for the function of an organ or of its tissues, for which primarily chemical or physical analysis is required." Pavlov's methodology involved training dogs to lie calmly on the operating table while he incised the skin and surface tissues, disclosed the artery, and connected it to instruments for measuring blood pressure. Pavlov's second independent work centered around digestion. He started studying digestion as early as 1879, and it was his major focus from 1890 to 1897. His work was an accumulation of observations on the nervous control of one organ system through the method of chronic experiment.

The study of digestion involved developing "fistulas" through which secretions from salivary glands, stomach, the pancreas, and small intestine could be collected. His technique was truly unique in that he did not cut the nerve supply nor contaminate the secretions with food. Pavlov's accomplishments from study of digestive organs included: discovery of enterokinase, an enzyme in the duodenum that activates trypsin description of the neural control of the pancreas and pancreatic control as a response to different foods demonstration that chewing and swallowing alone would cause gastric secretion conclusion that the secretory nerve that controls the gastric glands is the vagus nerve demonstration of variance in types and amounts of secretions of the stomach is a response to different foods observation that the mere sight of food stimulates salivary and gastric secretion In 1897, Pavlov published his results and generalizations in a book called "Work of the Digestive Glands". For this work, he was the first Russian and physiologist to receive the Nobel Prize, which was awarded in 1904. This last observation listed above marks the beginning of a shift of Pavlov's research focus.

He began to study the "higher mental processes", particularly the effects of sight and smell of food on salivation. He classified all the reactions of an animal as conditioned or unconditioned. The most famous and well-known experiment of Pavlov is that he conditioned dogs to initiate a salivary response to the sound of a bell. He began by measuring the amount of salivation in response to only food. As the experiments continued, he rang a bell as he presented the food. Again, he noted a salivary response. Finally, by only ringing the bell, Pavlov observed the same response as having presented food to the dogs - salivation. These experiments defined what has been a "conditioned response". It is this same principle that makes our our mouths water and stomachs awaken when we smell the odors of a restaurant or see the 'golden arches' come into view. The final 35 years of Pavlov's research were devoted to the investigation of the conditioned reflex and the study of the brain. In the late 1920's, he began working with clinical patients, trying to understand the qualitative differences between the higher nervous processes of animals and of people.

"Science will sooner or later bring the obtained objective results to our subjective world, and will at once illuminate our mysterious nature, will explain the mechanism and vital meaning of that which eternally occupies the human mind - it's conscience, and it's tribulations." The 'conditioning' model presented by Pavlov had an enormous influence on western behavioral psychology. For Pavlov, the assumption was that the unconscious processes that existed were simple reflexes which could be conditioned to affect behavioral change. Ivan Petrovich Pavlov can be thanked for maintaining the purity of observational science and striving to keep the standards for experimental methodology at its highest level. Although he is most remembered for his groundbreaking work in behavioral psychology, the inspiring research that led Pavlov to these observation cannot be forgotten. He was a truly great scientist and researcher. References Girogian, NA: Pavlov, Ivan Petrovich. In The Dictionary of Scientific Biography. Charles Schribner's Sons, New York, Vol 10, pp. 431-6, 1974. Kozulin, Alex. Personalities and Reflexes: The Legacies of Ivan Pavlov and Vladimir Bekterev.

In Psychology in Utopia: Toward a Social History of Soviet Psychology. MIT press, Cambridge, pp. 40-61, 1984. Thanks to Dr. Daniel Todes for translation of the opening quote from the original Russian. Last updated on April 24, 2006 Author: R. Bowen Ivan Pavlov - Science Shorts Comments Off on Ivan Pavlov Ivan Pavlov Posted by Bob Ivan Pavlov was a Russian scientist whose work bridged the disciplines of physiology and psychology. Although he was by training a doctor, his most significant contribution lay in the field of behavioral psychology. After working as an experimental researcher, Pavlov became head of the department of physiology at Russia’s Institute of Experimental Medicine. Pavlov received the Nobel Prize in 1904 for his classic experiments in the role of conditioned reflexes in dogs’ neurophysiology. As sometimes happens in the world of experimental research, Pavlov began his work in an rather ordinary undertaking which took a dramatic turn mid-course. Observations and events quite unrelated to the focus of the experiment took on greater import than the original purpose of the work. In essence, Pavlov’s study is quite easy to understand, yet its implications are profound.

Pavlov began experiments on the digestive activities of dogs. This included, quite simply, studying the saliva and gastric juices which are produced reflexively when food is placed into a dog’s mouth. However, over the course of the experiments, Pavlov noted that the dogs began to salivate when other environmental clues associated with food delivery were presented. Thus, the sound of a ticking metronome which always preceded food delivery could cause the dogs to begin to salivate. Perhaps this does not seem a profound insight on Pavlov’s part. But what he had inadvertently discovered was that inborn reflexes (such as the salivary reflex) could be conditioned to environmental stimuli (such as ticking metronomes). In psychological terms, the unconditioned stimulus (food) which inevitably produces an unconditioned response (salivation and gastric juice secretion) could be paired in such a way that a tone or a sight or a smell could come to elicit the same response (now called a conditioned response). There was no inborn reason why a dog should salivate upon hearing a tone, seeing a lab coat, or smelling a certain odour, but with close time associations, these same reflexes could be programmed to occur.

Pavlov discovered that even in the absence of food, these signals from the environment could cause the organism to respond with a conditioned reflex. Pavlov had discovered one of the key ways in which organisms learn. Reflexes are an important part of inborn survival tools, but learning to hone them through external clues makes the animal or the human much more adaptive and responsive to the nuances of the environment. A neutral event could be paired with a pleasant or an unpleasant unconditioned stimulus and the neutral signal would take on the ability to elicit the reaction. The organism is therefore in a more favourable state to meet the meal or the predator. Pavlov’s discovery lead to the beginnings of the science of behaviorism – in which an organism’s behavior could be objectively seen and measured. Behaviorism moved psychology from introspection about the mind, to a study of observable events in the environment. It became the second wave of psychological theorizing and methodology. Classical conditioning is used as a psychotherapy today primarily in desensitization procedures in phobias. It is thought that phobias might be learned by the pairing of rather harmless events with fear-producing ones. However, most adults with phobias seem unable to remember such occurrences.

Nevertheless, a counter-conditioning procedure can help them to alter their typical phobic responses. By learning to pair deep relaxation with mental images of their phobic situation, the fear response gradually begins to be marginalized. Relaxation and fear are incompatible responses. As relaxation becomes the conditioned response to the phobia, the fear response is reduced. weirdexperiments.com - pavlov weirdexperiments.com stories from the wilder side of science More 0 comments "The Mad Science Book" is the UK edition of the German bestseller "Das Buch der verrückten Experimente". The amazing stories of 113 strange experiments from the middle ages to today. Entertaining, mind opening, deeply researched, with original illustrations (the second volume has not yet been licensed for the UK or US. Foreign rights ). "Do embarrassement researchers ask you to suck a pacifier in public?" "Did Darwin play the bassoon for worms?" Know the answers? Then you are ready for the mad experiments quiz . Poll The weirdest experiments Visitors to this website voted for their favorite weird science experiment. The ranking: 1. The three Christs of Ypsilanti -Three men think they are Jesus.

What happens when they meet?(1959) full story 2. Diagnosing schizophrenics with spider webs (1955) full story 3. The hanging studies (1905) full story 4. Brilliantly saying nothing. Does anyone notice? (1970) full story 5. Staying in bed for one year (1986) full story 6. Crucifiying volunteers (1984) more Editions 매드 사이언스 북 (Puriwa Ipari 2008) Polish buy Pavlov only rings once The Russian medic Ivan Petrovich Pavlov is the holder of an unusual record: no set of scientific experiments has had more bands named after them than those that Pavlov conducted at the beginning of the 20th century with dogs. In the 1970s there was a rock band that went by the name of Pavlov’s Dog and the Condition Reflex Soul Revue and Concert Choir, while in the 1980s Ivan Pavlov and the Salivation Army made their debut.

The 1990s saw not only the bluegrass band called Pavlov’s Dawgs, but also a rock group called Conditioned Response, while the new millennium witnessed the appearance of the English folk outfit Pavlov’s Cat. Nor were musicians the only ones who lighted on Pavlov when scouting around for a name: ‘Pavlov’s Dog’ is also the name of a communications agency in Ireland, a pub in England, a theatre group in Canada, and a drink in the One World Café in Baltimore, USA, a blend of Kahlúa, Bailey’s and milk. Pavlov was awarded the Nobel Prize in 1904 for his researches into the digestive system. However, this is not the reason why his name is so well known nowadays. Rather, the source of his fame is the basic learning mechanism that he discovered quite by chance in the course of his studies. While undertaking his research into digestion, Pavlov also became interested in the function of the salivary glands, and in order to observe how they worked in living dogs, he channelled the animals’ saliva directly from the gland through a hole in their cheeks into a small measuring jar.

In doing so, he was trying to determine the composition of their saliva when he fed the dogs with different diets. However, a problem soon arose. After the dogs had been fed a couple of times, they began to secrete saliva as soon as they caught sight of the food. At first Pavlov regarded this effect as a disruptive element in his research and so devised ways of putting the food into the dogs’ mouths without alerting them in advance. Yet it transpired that the animals associated even quite subtle signals with feeding. The mere sight of the researcher or the sound of his footsteps were enough to stimulate the flow of saliva. It was not long, however, before Pavlov stopped regarding this phenomenon as a flaw in his experimental method and came to look on it as a new area of research in its own right. He conducted experiments in which he controlled the signals that occurred prior to feeding. Five seconds before feeding, a metronome was set in motion or an electric bell rung. After a few such couplings – in the case of the bell, a single ring was enough – the dogs’ saliva began to flow as soon as they heard the signal. The dogs had learned that they would be fed after the bell was rung.

Because the dogs interpreted even the faintest cues from their surroundings as signals for impending feeding, Pavlov had a new building with soundproofed rooms constructed in St Petersburg, in which he could perform all the necessary operations remotely via a system of cables and levers. The fundamental learning mechanism that Pavlov discovered through his experiments is known as ‘classical conditioning’. This involves pairing a natural combination of stimulus and response (i.e. food and salivation) with a new stimulus (i.e. a bell). In doing so, the new stimulus can only ever trigger an innate behaviour, though admittedly this can occur in almost any combination one could think of. On the other hand, the question of how new behaviours are learned was only investigated 30 years after Pavlov’s experiments by the American psychologist B.F. Skinner, using the socalled Skinner box. During his experiments, Pavlov also discovered how conditioning can be unlearned. It was only necessary to ring the bell a couple of times without then feeding the dog for the animal to forget the connection. This was the basic principle behind the later development of behavioural therapy, which involved patients being confronted under controlled conditions with precisely those situations that usually triggered anxiety, for example.

This technique was designed to break the association between certain situations and anxiety. Today, everyone is familiar with the concept of Pavlov’s dogs. Cultural commentators have used them to symbolize the common herd in Western industrial societies, who have allowed themselves to be trained by advertising into ‘consumer animals’ and who display predictable purchasing reactions when confronted with particular stimuli. Unlike Pavlov himself, who has gone down in history as one of the most famous scientists of all time, the bands named after him never made the breakthrough – or at least haven’t done so yet. The one that came closest was the rock group Pavlov’s Dog and the Condition Reflex Soul Revue and Concert Choir, who were rechristened simply Pavlov’s Dog in 1973 and paid $600,000 for their debut album, which at the time was the largest ever advance for a record in the USA. But three years later their record company dropped them, and the musicians found themselves broke and in dispute with one another. How Everyone Gets Pavlov Wrong - The New Yorker Ivan Pavlov’s real quest.

By Michael Specter Pavlov (operating on a dog in 1902) ran his lab like a factory; dogs were his machines.CreditCourtesy Wellcome Library, London As a college student, B. F. Skinner gave little thought to psychology. He had hoped to become a novelist, and majored in English. Then, in 1927, when he was twenty-three, he read an essay by H. G. Wells about the Russian physiologist Ivan Pavlov. The piece, which appeared in the Times Magazine, was ostensibly a review of the English translation of Pavlov’s “Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex.” But, as Wells pointed out, it was “not an easy book to read,” and he didn’t spend much time on it. Instead, Wells described Pavlov, whose systematic approach to physiology had revolutionized the study of medicine, as “a star which lights the world, shining down a vista hitherto unexplored.” That unexplored world was the mechanics of the human brain.

Pavlov had noticed, in his research on the digestive system of dogs, that they drooled as soon as they saw the white lab coats of the people who fed them. They didn’t need to see, let alone taste, the food in order to react physically. Dogs naturally drooled when fed: that was, in Pavlov’s terms, an “unconditional” reflex. When they drooled in response to a sight or sound that was associated with food by mere happenstance, a “conditional reflex” (to a “conditional stimulus”) had been created. Pavlov had formulated a basic psychological principle—one that also applied to human beings—and discovered an objective way to measure how it worked. Skinner was enthralled. Two years after reading the Times Magazine piece, he attended a lecture that Pavlov delivered at Harvard and obtained a signed picture, which adorned his office wall for the rest of his life. Skinner and other behaviorists often spoke of their debt to Pavlov, particularly to his view that free will was an illusion, and that the study of human behavior could be reduced to the analysis of observable, quantifiable events and actions.

But Pavlov never held such views, according to “Ivan Pavlov: A Russian Life in Science” (Oxford), an exhaustive new biography by Daniel P. Todes, a professor of the history of medicine at Johns Hopkins School of Medicine. In fact, much of what we thought we knew about Pavlov has been based on bad translations and basic misconceptions. That begins with the popular image of a dog slavering at the ringing of a bell. Pavlov “never trained a dog to salivate to the sound of a bell,” Todes writes. “Indeed, the iconic bell would have proven totally useless to his real goal, which required precise control over the quality and duration of stimuli (he most frequently employed a metronome, a harmonium, a buzzer, and electric shock).” Pavlov is perhaps best known for introducing the idea of the conditioned reflex, although Todes notes that he never used that term. It was a bad translation of the Russian uslovnyi, or “conditional,” reflex. For Pavlov, the emphasis fell on the contingent, provisional nature of the association—which enlisted other reflexes he believed to be natural and unvarying.

Drawing upon the brain science of the day, Pavlov understood conditional reflexes to involve a connection between a point in the brain’s subcortex, which supported instincts, and a point in its cortex, where associations were built. Such conjectures about brain circuitry were anathema to the behaviorists, who were inclined to view the mind as a black box. Nothing mattered, in their view, that could not be observed and measured. Pavlov never subscribed to that theory, or shared their disregard for subjective experience. He considered human psychology to be “one of the last secrets of life,” and hoped that rigorous scientific inquiry could illuminate “the mechanism and vital meaning of that which most occupied Man—our consciousness and its torments.” Of course, the inquiry had to start somewhere. Pavlov believed that it started with data, and he found that data in the saliva of dogs. Pavlov’s research originally had little to do with psychology; it focussed on the ways in which eating excited salivary, gastric, and pancreatic secretions. To do that, he developed a system of “sham” feeding.

Pavlov would remove a dog’s esophagus and create an opening, a fistula, in the animal’s throat, so that, no matter how much the dog ate, the food would fall out and never make it to the stomach. By creating additional fistulas along the digestive system and collecting the various secretions, he could measure their quantity and chemical properties in great detail. That research won him the 1904 Nobel Prize in Physiology or Medicine. But a dog’s drool turned out to be even more meaningful than he had first imagined: it pointed to a new way to study the mind, learning, and human behavior. “Essentially, only one thing in life is of real interest to us—our psychical experience,” he said in his Nobel address. “Its mechanism, however, was and still is shrouded in profound obscurity. All human resources—art, religion, literature, philosophy, and the historical sciences—all have joined in the attempt to throw light upon this darkness. But humanity has at its disposal yet another powerful resource—natural science with its strict objective methods.” Pavlov had become a spokesman for the scientific method, but he was not averse to generalizing from his results.

“That which I see in dogs,” he told a journalist, “I immediately transfer to myself, since, you know, the basics are identical.” Ivan Pavlov was born in 1849 in the provincial Russian city of Ryazan, the first of ten children. As the son of a priest, he attended church schools and the theological seminary. But he struggled with religion from an early age and, in 1869, left the seminary to study physiology and chemistry at St. Petersburg University. His father was furious, but Pavlov was undeterred. He never felt comfortable with his parents—or, as this biography makes clear, with almost anyone else. Not long after “The Brothers Karamazov” was published, Pavlov confessed to his future wife, Seraphima Vasilievna Karchevskaya, who was a friend of Dostoyevsky’s, that he identified with the rationalist Ivan Karamazov, whose brutal skepticism condemned him, as Todes notes, to nihilism and breakdown. “The more I read, the more uneasy my heart became,” Pavlov wrote in a letter to Karchevskaya.

“Say what you will, but he bears a great resemblance to your tender and loving admirer.” Pavlov entered the intellectual world of St. Petersburg at an ideal moment for a man eager to explore the rules that govern the material world. The tsar had freed the serfs in 1861, helping to push Russia into the convulsive century that followed. Darwin’s theory of evolution was starting to reverberate across Europe. Science began to matter in Russia in a way it hadn’t before. At the university, Pavlov’s freshman class in inorganic chemistry was taught by Dmitri Mendeleev, who, a year earlier, had created the periodic table of the elements as a teaching tool. The Soviets would soon assign religion to the dustbin of history, but Pavlov got there ahead of them. For him, there was no religion except the truth. “It is for me a kind of God, before whom I reveal everything, before whom I discard wretched worldly vanity,” he wrote.

“I always think to base my virtue, my pride, upon the attempt, the wish for truth, even if I cannot attain it.” One day, while walking to his lab at the Institute for Experimental Medicine, Pavlov watched with amazement as a medical student stopped in front of a church and crossed himself. “Think about it!” Pavlov told his colleagues. “A naturalist, a physician, but he prays like an old woman in an almshouse!” Pavlov was not a pleasant person. Todes presents him as a volatile child, a difficult student, and, frequently, a nasty adult. For decades, his lab staff knew to stay away, if at all possible, on his “angry days,” and there were many. As a member of the liberal intelligentsia, he was opposed to restrictive measures aimed at Jews, but in his personal life he freely voiced anti-Semitic sentiments. Pavlov once referred to “that vile yid, Trotsky,” and, when complaining about the Bolsheviks in 1928, he told W.

Horsley Gantt, an American scientist who spent years in his lab, that Jews occupied “high positions everywhere,” and that it was “a shame that the Russians cannot be rulers of their own land.” In lectures, Pavlov insisted that medicine had to be grounded in science, on data that could be explained, verified, and analyzed, and on studies that could be repeated. Drumming up support among physicians for the scientific method may seem banal today, but at the end of the nineteenth century it wasn’t an easy sell. In Russia, and even to some degree in the West, physiology was still considered a “theoretical science,” and the connection between basic research and medical treatments seemed tenuous. Todes argues that Pavlov’s devotion to repeated experimentation was bolstered by the model of the factory, which had special significance in a belatedly industrializing Russia. Pavlov’s lab was essentially a physiology factory, and the dogs were his machines. To study them, he introduced a rigorous experimental approach that helped transform medical research. He recognized that meaningful changes in physiology could be assessed only over time. Rather than experiment on an animal once and then kill it, as was common, Pavlov needed to keep his dogs alive.

He referred to these studies as “chronic experiments.” They typically involved surgery. “During chronic experiments, when the animal, having recovered from its operation, is under lengthy observation, the dog is irreplaceable,” he noted in 1893. “This conversation may be recorded for training purposes and used in a hilarious mix for our annual office party.” Buy a cartoon The dogs may have been irreplaceable, but their treatment would undoubtedly cause an outcry today. Todes writes that in early experiments Pavlov was constantly stymied by the difficulty of keeping his subjects alive after operating on them. One particularly productive dog had evidently set a record by producing active pancreatic juice for ten days before dying. The loss was a tremendous disappointment to Pavlov. “Our passionate desire to extend experimental trials on such a rare animal was foiled by its death as a result of extended starvation and a series of wounds,” Pavlov wrote at the time. As a result, “the expected resolution of many important and controversial questions” had been delayed, awaiting another champion test subject. If Pavlov’s notes were voluminous, Todes’s own investigations are hardly modest. He spent years researching this biography and has made excellent use of archives in Russia, Europe, and the United States.

No scholar of Pavlov or of the disciplines he inspired will be able to ignore this achievement. The book’s eight hundred and fifty-five pages are filled with a vast accumulation of data, although the reader might have been better served if Todes had left some of it out. No minutia appears to have been too obscure to include. Here is Todes describing data that Pavlov had assembled from one extended experiment: “The total amount of secretion in trials 6 and 8 is too low, and the slope of these curves diverges markedly at several points from that in trial 1. Trial 9 fits trial 1 more snugly than does trial 5 in terms of total secretion, but the amount of secretion more than doubles in the second hour, contrasting sharply with the slight decline in trial 1. Trial 10 is again a good fit in terms of total amount of secretion, but the amount of secretion rises inappropriately in the fourth hour.” The diligent reader can also learn, in excruciating detail, what time Pavlov took each meal during summer holidays (dinner at precisely 12:30 P .

M ., tea at four, and supper at eight), how many cups of tea he typically consumed each afternoon (between six and ten), and where the roses were planted in his garden (“around the spruce tree on the west side of the veranda”). It’s hard not to wish that Todes had been a bit less devoted to his subject’s prodigious empiricism. For more than thirty years, Pavlov’s physiology factory turned out papers, new research techniques, and, of course, gastric juice—a lot of it. On a good day, a hungry dog could produce a thousand cubic centimetres, more than a quart. Although this was a sideline for Pavlov, the gastric fluids of a dog became a popular treatment for dyspepsia, and not just in Russia. A “gastric juice factory” was set up for the purpose. “An assistant was hired and paid thirty rubles a month to oversee the facility,” Todes writes. “Five large young dogs, weighing sixty to seventy pounds and selected for their voracious appetites, stood on a long table harnessed to the wooden crossbeam directly above their heads. Each was equipped with an esophagotomy and fistula from which a tube led to the collection vessel.

Each ‘factory dog’ faced a short wooden stand tilted to display a large bowl of minced meat.” By 1904, the venture was selling more than three thousand flagons of gastric juice annually, Todes writes, and the profits helped increase the lab budget by about seventy per cent. The money was helpful. So was the apparent demonstration that a product created in an experimental laboratory could become useful to doctors all over the world. At the turn of the century, Pavlov had begun focussing his research on “psychic secretions”: drool produced by anything other than direct exposure to food. He spent most of the next three decades exploring the ways conditional reflexes could be created, refined, and extinguished. Before feeding a dog, Pavlov might set a metronome at, say, sixty beats a minute. The next time the dog heard a metronome at any speed, it would salivate. But when only that particular metronome setting was reinforced with food the dog became more discriminating.

Pavlov deduced that there were colliding forces of “excitation” and “inhibition” at play—so that, at first, the stimulus spreads across the cerebral cortex and then, in the second phase, it concentrates at one specific spot. As his formulations and models grew more complex, Pavlov was encouraged in his hope that he would be able to approach psychology through physiology. “It would be stupid to reject the subjective world,” he remarked later. “Our actions, all forms of social and personal life are formed on this basis. . . . The question is how to analyze this subjective world.” Pavlov was sixty-eight and had been famous for years when Lenin came to power, and Todes is at his best in describing the scientist’s relationship with the regime that he would serve for the rest of his life. Pavlov harbored no sentimental attachment to the old order, which had never been aggressive in funding scientific research. The Bolsheviks promised to do better (and, eventually, they did). Yet Pavlov considered Communism a “doomed” experiment that had turned Russia back into a nation of serfs. “Of course, in the struggle between labor and capital the government must stand for the protection of the worker,” he said in a speech.

“But what have we made of this? . . . That which constitutes the culture, the intellectual strength of the nation, has been devalued, and that which for now remains a crude force, replaceable by a machine, has been moved to the forefront. All this, of course, is doomed to destruction as a blind rejection of reality.” Lenin had too many other problems to spend his time worrying about one angry scientist. At first, Pavlov, his wife, and their four children were treated like any other Soviet citizens. Their Nobel Prize money was confiscated as property of the state. From 1917 to 1920, like most residents of Petrograd, which would soon be called Leningrad, the Pavlovs struggled to feed themselves and to keep from freezing. It was nearly a full-time occupation; at least a third of Pavlov’s colleagues at the Russian Academy of Sciences died in those first post-revolutionary years. “Some starved to death in apartments just above or below his own in the Academy’s residence,” Todes writes. Pavlov grew potatoes and other vegetables right outside his lab, and when he was sick a colleague provided small amounts of firewood to burn at home.

In 1920, Pavlov wrote to Lenin’s secretary, Vladimir Bonch-Bruevich, seeking permission to emigrate, although, as Todes points out, it was probably not yet necessary to ask. Pavlov wanted to see if, as he suspected, universities in Europe or America would fund his research in circumstances that would prevent his dogs and lab workers from starving. Bonch-Bruevich turned the letter over to Lenin, who immediately grasped the public-relations repercussions of losing the country’s most celebrated scientist. He instructed Petrograd Party leaders to increase rations for Pavlov and his family, and to make sure his working conditions improved. The Soviets came to regard Pavlov as a scientific version of Marx. The comparison could not entirely have pleased Pavlov, who rebelled at the “divine” authority accorded Marx (“that fool”) and denied that his own “approach represents pure materialism.” Indeed, where others thought that the notion of free will would come to be discarded once we had a full understanding of how the mind worked, Pavlov was, at least at times, inclined to think the opposite.

“We would have freedom of the will in proportion to our knowledge of the brain,” he told Gantt in 1927, just as “we had passed from a position of slave to a lord of nature.” That year, Stalin began a purge of intellectuals. Pavlov was outraged. At a time when looking at the wrong person in the wrong way was enough to send a man to the gulag, he wrote to Stalin saying that he was “ashamed to be called a Russian.” Nikolai Bukharin, who considered Pavlov indispensable, made the case for him: “I know that he does not sing the ‘Internationale,’ ” Bukharin wrote to Valerian Kuibyshev, the head of the state planning committee. “But . . . despite all his grumbling, ideologically (in his works, not in his speeches) he is working for us.” Stalin agreed. Pavlov prospered even at the height of the Terror. By 1935-36, he was running three separate laboratories and overseeing the work of hundreds of scientists and technicians. He was permitted to collaborate with scholars in Europe and America. Still, his relationship with the government was never easy.

Soviet leaders even engaged in a debate over whether to celebrate his eightieth birthday. “A new nonsensical letter from academician Pavlov,” Molotov wrote in the margin of a letter of complaint before it was passed to Stalin. Kuibyshev was deeply opposed to any state recognition. “Pavlov spits on the Soviets, declares himself an open enemy, yet Soviet power would for some reason honor him,” he grumbled. “Help him we must,” he said at the time, “but not honor him.” For a while, Kuibyshev prevailed, but in 1936, when Pavlov died, at eighty-six, a hundred thousand mourners, including Party officials, filed past his casket as he lay in state. What Todes describes as Pavlov’s “grand quest”—to rely on saliva drops and carefully calibrated experiments to understand the mechanics of human psychology—lives on, in various forms. Classical conditioning remains a critical tool: it is widely used to treat psychiatric disorders, particularly phobias. But the greater pursuit is for a kind of unified field theory in which psychology and physiology—the subjective and the material realms—would finally be integrated.

And so we have entered the age of the brain. The United States and other countries have embarked upon brain-mapping initiatives, and Pavlov would have endorsed their principal goal: to create a dynamic picture of the brain that demonstrates, at the cellular level, how neural circuits interact. As Todes points out, while Pavlov examined saliva in his attempts to understand human psychology, today we use fMRIs in our heightened search for the function of every neuron. When he delivered his lectures on the “larger hemispheres of the brain,” Pavlov declared, “We will hope and patiently await the time when a precise and complete knowledge of our highest organ, the brain, will become our profound achievement and the main foundation of a durable human happiness.” We are still waiting, but less patiently than before. ♦ Michael Specter has been a staff writer at The New Yorker since 1998, and has written frequently about AIDS, T.B., and malaria in the developing world, as well as about agricultural biotechnology, avian influenza, the world’s diminishing freshwater resources, and synthetic biology. Psychology History Ivan Pavlov was a Russian physiologist whose research on the physiology of digestion led to the development of the first experimental model of learning, Classical Conditioning.

Most of his research was gathered studying salivating dogs. An illustrated review of Pavlov's experiments is available on the [ Discovery Web Site ]. Pavlov was born on September 14, 1849, at Ryazan, Russia. Because he was born into a large family, poverty was always an issue. His father, Peter Dmitrievich Pavlov, was the village priest and young Ivan tended to the church property. Pavlov inherited many of his father's characteristics including a strong will to succeed. The oldest sibbling, Ivan Pavlov was also among the healthiest. He began school at the Ryazan Ecclesiastical High School. Pavlov and his brothers eventually entered the Ryazan Ecclesiastical Seminary. At the Seminary, he planned to pursue a career in theology. However, after being introduced to the works of Charles Darwin and Ivan Sechenov, Pavlov decided to transfer to the University of St. Petersburg to gain knowledge about natural science. There, Pavlov gained great respect for a professor of physiology, Cyon. Due to Cyon's enthusiasm for physiology, he decided to become a physiologist during his third year.

At that point, Pavlov started work as an assistant in a laboratory in which he earned 50 rubles a month. Eventually, Pavlov's research on the physiology of digestion would earn him the Nobel Prize. As a skilled surgeon, he was able to implant small stomach pouches in dogs to measure the secretion of gastric juices produced when the dogs began to eat. With the help of his assistants, he was able to condition the dogs to salivate at the click of a metronome. As his work progressed, Pavlov established the basis for conditioned reflexes and the field of classical conditioning. Theory Pavlov concluded that he was able to pair a neutral stimulus with an excitatory one and have the neutral stimulus eventually elicit the response the was associated with the original, unlearned reflex. In Classical Conditioning terminology, an unconditioned stimulus (US) is an event that causes a response to occur, which is referred to as the unconditioned response (UR). And, in Pavlov's study with dogs, the food within the dog's mouth is the US, and the salivation that results is the UR.

Pavlov took a step further and added an element known as the nonexcitatory, conditioned stimulus (CS), which is paired with the US. Pavlov used a metronome as the CS which he rang first, then fed the dogs. This pairing would eventually establish the dog's conditioned response of salivating to the sound of the metronome. After repeating this procedure several times, Pavlov was able to remove the US (food) and by only ringing the bell the dogs would salivate (CR). Since the bell alone now produced the unconditioned response (salivation), the association had been established (Conditioned). Pavlov continued to present the CS with any pairing with the US until the CR no longer occurred. This elimination of the CR is known as extinction. However, waiting a few days and then reintroducing ticking metronome resulted in the dogs once again salivating to the CS. Pavlov termed this, spontaneous recovery. Pavlov continued of the conditioned response. He replaced the metronome with other stimuli for use as the CS.

He conditioned the dogs using a buzzer, the flash of a light, a touch on the dog's harness, and the use of different pitches of a whistle in which the dogs had to differentiate between to determine which pitch resulted in access to food. Pavlov's experimental research gained much respect throughout Russia as well as America and the rest of the nations. Although he began his investigations late in life he managed to develop the major constructs of a fully realized field of learning. He summarized his discoveries in his remarkable book, Conditioned Reflexes. Time Line September 14, 1894 Born in Ryazan, Russia 1870 Leaving his religious career, Pavlov enrolled to take a natural science course at the University of St. Pertersburg 1875 Graduated from the University of St. Pertersburg and took an assistantship from Cyon in his laboratory at the Military-Medical Academy; received the degree of Candidate of Natural Sciences 1876-78 Becomes an assistant in Ustimovich's laboratory Summer of 1877 He spent time in Physiological Laboratory of Professor R.

Heidenhain at Breslau 1879 Graduated from the Military-Medical Academy 1879 Completed third course of study at the Academy of Medical Surgery; awarded his first gold medal 1879-1904 Wrote for a volume in commemoration of the 25th Graduation Anniversary from the Military-Medical Academy June 13, 1880 Proposed to Seraphima (Sara) Vasilievna karchevskaya 1880-84 Postgraduate study and research at the Academy 1881 Married Sara 1883 Discovered dynamic nerves of the heart and submitted thesis for the degree of Doctor of Medicine April 24, 1884 Made a lecturer in physiology at the Military-Medical Academy 1885-86 Studied abroad June 15, 1890 Made chair and appointed professor of pharmacology in the Military-Medical Academy 1890 Appointed director of physiology department at the Institute of Experimental Medicine in St.

Petersburg June 13, 1891 Gained directorship of the Department of Physiology in the Institute of Experimental Medicine 1891-1900 Did most of his research on physiology of digestion at the Institute of Experimental Medicine May 29, 1895 Appointed to Chair of Physiology until 1925 1897 Published his lectures entitled Lectures on the functions of the principal digestive glands 1901 Elected as a corresponding member of the Russian Academy of Sciences 1904 Received Nobel Prize in Physiology and Medicine for work on the physiology of the digestive glands 1907 Elected Academician of the Russian Academy of Sciences 1912 Given an honorary doctorate at Cambridge University 1915 Awarded the Order of the legion of Honour (Medical Academy of Paris recommendation) January 24, 1921 Awarded a special government decree signed by Lenin 1924 Resigned from professorship at the Military-Medical Academy 1935 Youngest son, Vsevolod, died 1935 Government built a laboratory for Pavlov with his chief work on conditioned reflexes 193

6 On February 27, Pavlov died in Leningrad Babkin, B.P.

(1949). Pavlov: A Biography. Toronto, Canada: The University of Chicago Press. Hothersall, David. (1995). History of Psychology. New York: McGraw-Hill, Inc. pp. 239-253. Morris, C.G., and Maisto, A.A. (1999). Understanding Psychology. 4th ed. New Jersey: Prentice Hall, Inc. WEBSITES: "Pavlov, Ivan Petrovich". Available: Provides the year of birth and death, birthplace, and career field of Pavlov. "Ivan Petrovich Pavlov". Available: Provides factual information about Pavlov's life both personal and career related. What Is Classical Conditioning? (And Why Does It Matter?) - Scientific American Blog Network What Is Classical Conditioning? (And Why Does It Matter?) By Jason G. Goldman on January 11, 2012 Share on Facebook Advertisement | Report Ad Classical conditioning is one of those introductory psychology terms that gets thrown around.

Many people have a general idea that it is one of the most basic forms of associative learning, and people often know that Ivan Pavlov's 1927 experiment with dogs has something to do with it, but that is often where it ends. Classical Conditioning, Explained The most important thing to remember is that classical conditioning involves automatic or reflexive responses, and not voluntary behavior (that's operant conditioning, and that is a different post ). What does this mean? For one thing, that means that the only responses that can be elicited out of a classical conditioning paradigm are ones that rely on responses that are naturally made by the animal (or human) that is being trained. Also, it means that the response you hope to elicit must occur below the level of conscious awareness - for example, salivation, nausea, increased or decreased heartrate, pupil dilation or constriction, or even a reflexive motor response (such as recoiling from a painful stimulus). In other words, these sorts of responses are involuntary. The basic classical conditioning procedure goes like this: a neutral stimulus is paired with an unconditional stimulus (UCS). The neutral stimulus can be anything, as long as it does not provoke any sort of response in the organism.

On the other hand, the unconditional stimulus is something that reliably results in a natural response. For example, if you shine a light into a human eye, the pupil will automatically constrict (you can actually see this happen if you watch your eyes in a mirror as you turn on and off a light). Pavlov called this the "unconditional response." (UCR) As soon as the neutral stimulus is presented with the UCS, it becomes a conditional stimulus (CS). If the CS and UCS always occur together, then the two stimuli would become associated over time. The response that was initially produced in response to the UCS would also be produced in response to the CS, even if it was presented alone. Pavlov called this the "conditional response." (CR) To make this a bit more concrete, we'll use Pavlov's dogs as an example. Before learning took place, the dogs would reliably salivate (UCR) when given meat powder (UCS), but they gave no response to the ringing of a bell (neutral). Then Pavlov would always ring a bell just before he would present the dogs with some meat powder. Pretty soon, the dogs began to associate the sound of the bell with the impending presence of meat powder.

As a result, they would begin to salivate (CR) as soon as they heard the bell (CS), even if it was not immediately followed by the meat powder (UCS). In other words, they learned that the bell was a reliable predictor of meat powder. In this way, Pavlov was able to elicit an involuntary, automatic, reflexive response to a previously neutral stimulus. Note that most English-language textbooks use the terms "unconditioned stimulus," "unconditioned response," and so on. This is due to a translation error from Pavlov's Russian to English. The better translation would be "conditional." Want an infographic? Of course you do: Real-world Examples of Classical Conditioning Classical conditioning can help us understand how some forms of addiction, or drug dependence, work. For example, the repeated use of a drug could cause the body to compensate for it, in an effort to counterbalance the effects of the drug. This causes the user to require more of the substance in order to get the equivalent effect (this is called tolerance). However, the development of tolerance also takes into account other environmental variables (the conditional variables) - this is called the situational specificity of tolerance.

For example, alcohol tends to taste a certain way, and when alcohol is consumed in the usual way, the body responds in an effort to counteract the effect. But, if the alcohol is delivered in a novel way (such as in Four Loko ), the individual could overdose. This effect has also been observed among those who have become tolerant to otherwise lethal amounts of opiates: they may experience an overdose if they take their typical dose in an atypical setting. These results have been found in species ranging from rats and mice to humans. In these examples, it's the environmental context (conditional stimuli) that prompts the body to prepare for the drug (the conditional response). But if the conditional stimuli are absent, the body is not able to adequately prepare itself for the drug, and bad things could happen. Another example of classical conditioning is known as the appetizer effect. If there are otherwise neutral stimuli that consistently predict a meal, they could cause people to become hungry, because those stimuli induce involuntary changes in the body, as a preparation for digestion. There's a reason it's called the "dinner bell," after all. Classical conditioning is also being used in wildlife conservation efforts!

At Extinction Countdown, John Platt pointed out last month that taste aversion, which is a form of classical conditioning, is being used to keep lions from preying on cattle . This should, in turn, prevent farmers from killing the lions. Given and his team of researchers gave eight of the cats meals of beef treated with the deworming agent thiabendazole in doses large enough to make them temporarily sick to their stomachs. “It basically causes a bad case of indigestion,” WildiZe founder Eli Weiss told The Aspen Times. After a few meals of treated beef, the lions were once again offered untreated meat. Seven of the eight refused to eat it, while an eighth actually refused to eat at all for a short period. In this example, the meat is actually the neutral stimulus, when paired with the deworming agent (UCS). The unconditional response is the feeling of being sick. Thus, the feeling of being sick (CR) was associated with the beef (CS), resulting in aversion to beef. Finally, following a conversation on twitter recently, cartoonist Joseph Hewitt pointed out another example of classical conditioning: Can you think of other real-world examples of classical conditioning? Leave them in the comments!

Related: The views expressed are those of the author(s) and are not necessarily those of Scientific American. Advertisement | ABOUT THE AUTHOR(S) Jason G. Goldman Jason G. Goldman is a science journalist based in Los Angeles. He has written about animal behavior, wildlife biology, conservation, and ecology for Scientific American, Los Angeles magazine, The Washington Post, The Guardian, the BBC, Conservation magazine, and elsewhere. He contributes to Scientific American's "60-Second Science" podcast, and is co-editor of Science Blogging: The Essential Guide (Yale University Press). He enjoys sharing his wildlife knowledge on television and on the radio, and often speaks to the public about wildlife and science communication. Recent Articles Basic Principles of Classical Conditioning: Pavlov About Watch and Favorite Watch Watching this resources will notify you when proposed changes or new versions are created so you can keep track of improvements that have been made. Favorite Favoriting this resource allows you to save it in the “My Resources” tab of your account. There, you can easily access this resource later when you’re ready to customize it or assign it to your students.

Basic Principles of Classical Conditioning: Pavlov Ivan Pavlov's research on classical conditioning profoundly informed the psychology of learning and the field of behaviorism. Learning Objective Summarize the process of classical conditioning Key Points Ivan Pavlov is known for his famous experiment with conditioning the salivation response in dogs, which brought about classical conditioning . Classical conditioning is a form of learning whereby a conditioned stimulus becomes associated with an unrelated unconditioned stimulus, in order to produce a behavioral response known as a conditioned response. By teaching dogs to associate the sound of a buzzer with being fed, Pavlov established the principles of classical conditioning. Various behavior therapies for managing fear and anxiety , such as desensitization and flooding, have been developed from Pavlov's work. Terms Register for FREE to remove ads and unlock more features! Learn more Full Text Ivan Pavlov (1849–1936) was a Russian scientist whose work with dogs has been influential in understanding how learning occurs. Through his research, he established the theory of classical conditioning. Pavlov is known for his studies in classical conditioning, which have been influential in understanding learning.

Basic Principles of Classical Conditioning Classical conditioning is a form of learning whereby a conditioned stimulus (CS) becomes associated with an unrelated unconditioned stimulus (US) in order to produce a behavioral response known as a conditioned response (CR). The conditioned response is the learned response to the previously neutral stimulus. The unconditioned stimulus is usually a biologically significant stimulus such as food or pain that elicits an unconditioned response (UR) from the start. The conditioned stimulus is usually neutral and produces no particular response at first, but after conditioning it elicits the conditioned response. Extinction is the decrease in the conditioned response when the unconditioned stimulus is no longer presented with the conditioned stimulus. When presented with the conditioned stimulus alone, the individual would show a weaker and weaker response, and finally no response. In classical-conditioning terms, there is a gradual weakening and disappearance of the conditioned response. Related to this, spontaneous recovery refers to the return of a previously extinguished conditioned response following a rest period. Research has found that with repeated extinction/recovery cycles, the conditioned response tends to be less intense with each period of recovery. Pavlov's Famous Study The best-known of Pavlov's experiments involves the study of the salivation of dogs.

Pavlov was originally studying the saliva of dogs as it related to digestion, but as he conducted his research, he noticed that the dogs would begin to salivate every time he entered the room—even if he had no food. The dogs were associating his entrance into the room with being fed. This led Pavlov to design a series of experiments in which he used various sound objects, such as a buzzer, to condition the salivation response in dogs. He started by sounding a buzzer each time food was given to the dogs and found that the dogs would start salivating immediately after hearing the buzzer—even before seeing the food. After a period of time, Pavlov began sounding the buzzer without giving any food at all and found that the dogs continued to salivate at the sound of the buzzer even in the absence of food. They had learned to associate the sound of the buzzer with being fed. If we look at Pavlov's experiment, we can identify the four factors of classical conditioning at work: The unconditioned response was the dogs' natural salivation in response to seeing or smelling their food. The unconditioned stimulus was the sight or smell of the food itself.

The conditioned stimulus was the ringing of the bell, which previously had no association with food. The conditioned response, therefore, was the salivation of the dogs in response to the ringing of the bell, even when no food was present. Pavlov had successfully associated an unconditioned response (natural salivation in response to food) with a conditioned stimulus (a buzzer), eventually creating a conditioned response (salivation in response to a buzzer). With these results, Pavlov established his theory of classical conditioning. Before conditioning, an unconditioned stimulus (food) produces an unconditioned response (salivation), and a neutral stimulus (bell) does not have an effect. During conditioning, the unconditioned stimulus (food) is presented repeatedly just after the presentation of the neutral stimulus (bell). After conditioning, the neutral stimulus alone produces a conditioned response (salivation), thus becoming a conditioned stimulus. Neurological Response to Conditioning Consider how the conditioned response occurs in the brain. When a dog sees food, the visual and olfactory stimuli send information to the brain through their respective neural pathways, ultimately activating the salivation glands to secrete saliva. This reaction is a natural biological process as saliva aids in the digestion of food.

When a dog hears a buzzer and at the same time sees food, the auditory stimulus activates the associated neural pathways. However, because these pathways are being activated at the same time as the other neural pathways, there are weak synapse reactions that occur between the auditory stimulus and the behavioral response. Over time, these synapses are strengthened so that it only takes the sound of a buzzer (or a bell) to activate the pathway leading to salivation. Behaviorism and Other Research Pavlov's research contributed to other studies and theories in behaviorism, which is an approach to psychology interested in observable behaviors rather than the inner workings of the mind. The philosopher Bertrand Russell argued that Pavlov's work was an important contribution to a philosophy of mind. Pavlov's research also contributed to Hans Eysench's personality theory of introversion and extroversion . Eysench built upon Pavlov's research on dogs, hypothesizing that the differences in arousal that the dogs displayed was due to inborn genetic differences. Eysench then extended the research to human personality traits . Pavlov's research further led to the development of important behavior-therapy techniques, such as flooding and desensitizing, for individuals who struggle with fear and anxiety.

Desensitizing is a kind of reverse conditioning in which an individual is repeatedly exposed to the thing that is causing the anxiety. Flooding is similar in that it exposes an individual to the thing causing the anxiety, but it does so in a more intense and prolonged way.

Question: With which animal is the scientist Pavlov associated
Answer: Dogs