Pavlov, Ivan

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PAVLOV, IVAN

PAVLOV, IVAN (1849–1936), Russian physiologist.

Born in Ryazan, central Russia, the son of a priest, Ivan Petrovich Pavlov was inspired by progressive ideas in the early 1870s to study the natural sciences, and he received a doctor of medicine degree from St. Petersburg University in 1883 for his thesis "The Centrifugal Nerves of the Heart." He then studied for two years in Germany, before becoming director of physiology at the St. Petersburg Institute for Experimental Medicine, where he stayed for many years.

Pavlov's research was groundbreaking and laid the foundations for the development of key branches of physiological psychology. His first set of research interests focused on mammalian digestion, where he determined three phases of absorption and confirmed that a specific hormone was responsible for pancreatic secretion. He also observed that gastric juices could be made to flow even when no food had entered the stomach of an animal. It was for this area of investigation, the results of which were published as "Lectures on the Function of the Principal Digestive Glands" of 1897, that Pavlov was awarded a Nobel prize in 1904. He was the first Russian scientist to be so honored. This work also involved innovative surgical techniques that enabled the continuous observation of organs. However, the area of research that he is more closely associated with, and through which he is linked by name—"Pavlov's dogs"—is conditioned reflexes, which he pursued from 1902 onward.

Developing his initial interest in what he called the psychic secretion of the digestive glands, Pavlov investigated how food inserted into the mouth of a dog produced a flow of gastric juices, this reaction being termed an "unconditioned reflex" or an inherited nervous response. But if a bell was sounded alongside the insertion of food, and this association was repeated, then eventually the dog would salivate on hearing the bell alone, this reaction being termed a "conditioned reflex" or a learned physiological response. This idea was first reported at a conference in Madrid in 1903, and the experiment was part of a larger study of the psychopathology of the living organism in its entirety. Although the popular conception of salivating canines being strapped into a testing frame is nowadays something of a visual pun, in fact Pavlov's work remains part of the contemporary approach to understanding the nature of animal learning, with terms such as "stimulus-response learning" and "classical (or Pavlovian) conditioning" enduring in the literature.

Moreover the results of Pavlov's experiments on dogs were used to provide a more general theory of higher nervous activity in which reflex actions were analyzed in terms of the underlying neural activity that generated them. An initial external stimulus was seen to progress through chains of neurons in the brain to certain muscles or glands in the body, causing the reflex action to occur. Further related enquiry revealed the laws governing the functioning of the cerebral hemispheres. However the notion that conditioning experiments on animals might be an important tool in explaining human behavior fell out of favor with the decline of mechanistic behaviorism in psychology, and the advent of the cognitive revolution focusing on mental processes at the end of the 1970s.

In historical terms, Pavlov's physiological researches before 1917 can be located in a broader "silver age" of Russian natural science culminating in the period of the belle epoque, viewed together with the contributions of other world-famous Russian scientists like Dmitri Mendeleev (1834–1907) on chemical periodicity and Nikolai Lobachevsky (1792–1856) on non-Euclidian geometry. Pavlov built directly on the contributions of older scientists like Ivan Sechenov (1829–1905), the father of Russian physiology, who published a paper on "Reflexes of the Brain" in 1863 that characterized thoughts as reflexes.

After 1917 Pavlov's life constituted a unique case. He was in no sense a Marxist and even criticized Soviet communism on some occasions; his international stature as a scientist gave him a license to be difficult. In 1921 Vladimir Lenin (1870–1924) signed a governmental decree implying that special dispensation should be given to Pavlov's "outstanding scientific services," and a new center for his work was constructed in an area later named Pavlovo. Lenin's apparently admirable concern for scientific progress is however quickly diminished in light of the fact that Pavlov's work on conditioning was (at the time) seen to have propaganda application.

Perhaps as a consequence of such favorable treatment, and partly due to being singled out by the Communist Academy as refusing to cooperate with Soviet power, in the 1930s Pavlov publicly praised the Soviet government's emphasis on science and education, but henceforth remained silent about its political system. Pavlov was not targeted in the purges that occurred in the USSR throughout the 1930s and he died of natural causes in 1936, leaving a legacy of distinguished pupils and world-class physiological institutions.

See alsoScience and Technology.