Ivan Petrovich Pavlov ( September 14, 1849 – February 27, 1936) was a Russian physiologist, psychologist, and physician. He was awarded the Nobel Prize in Physiology or Medicine in 1904 for research pertaining to the digestive system. Pavlov is widely known for first describing the phenomenon of classical conditioning.
Pavlov was born in Ryazan, Russia. He began his higher education as a student at the Ryazan Ecclesiastical Seminary, but then dropped out and enrolled in the University of St. Petersburg to study the natural sciences. He received his doctorate in 1879.
In the 1890s, Pavlov was investigating the gastric function of dogs by externalizing a salivary gland so he could collect, measure and analyze the saliva many had in response to food under different conditions. Ivan noticed that the dogs tended to salivate before food coated with chili powder was actually delivered to their mouths. He decided that this was more interesting than the chemistry of saliva, and changed the focus of his research, carrying out a long series of experiments in which he manipulated the stimuli occurring before the presentation of food. Pavlov thereby established the basic laws for the establishment and extinction of what he called "conditional reflexes" — i.e., reflex responses, like salivation, that only occurred conditionally upon specific previous experiences of the animal. These experiments were carried out in the 1890s and 1900s, and were known to western scientists through translations of individual accounts, but first became fully available in English in a book published in 1927.
Unlike many pre-revolutionary scientists, Pavlov was highly regarded by the Soviet government, and he was able to continue his researches until he reached a considerable age. Moreover, he was praised by Lenin and as a Nobel laureate he was seen as a valuable political asset.
After the murder of Sergei Kirov in 1934, Pavlov wrote several letters to Molotov criticizing the mass persecutions, which followed and asking for the reconsideration of cases pertaining to several people he knew personally.
Conscious until his very last moment, Pavlov asked one of his students to sit beside his bed and to record the circumstances of his dying. He wanted to create unique evidence of subjective experiences of this terminal phase of life. The great scientific courage of Pavlov is exhibited by this story: he tried to learn, and to increase knowledge of physiology, even on his deathbed.
Reflex System Research
Pavlov contributed to many areas of physiology and neurology. Most of his work involves research in temperament, conditioning and involuntary reflex actions.
Pavlov performed and directed experiments on digestion, which earned him the 1904 Nobel Prize in Physiology and Medicine. Experiments included surgically extracting portions of the digestive system from animals, severing nerve bundles to determine the effects, and implanting fistulas between digestive organs and an external pouch to examine the organ's contents. This research served as a base for broad research on the digestive system.
Further work on reflex actions involved involuntary reactions to stress and pain. Pavlov extended the definitions of the four temperament types under study at the time: phlegmatic, choleric, sanguine, and melancholic. Pavlov and his researchers observed and began the study of transmarginal inhibition (TMI), the body's natural response of shutting down when exposed to overwhelming stress or pain. This research showed how all temperament types responded to the stimuli the same way, but different temperaments move through the responses at different times.
Pavlov's term "conditional reflex" was mistranslated from the Russian as "conditioned reflex", and other scientists reading his work concluded that since such reflexes were conditioned, they must be produced by a process called conditioning. As Pavlov's work became known in the West, particularly through the writings of John B. Watson, the idea of "conditioning" as an automatic form of learning became a key concept in the developing specialism of comparative psychology, and the general approach to psychology that underlay it, behaviorism. The British philosopher Bertrand Russell was an enthusiastic advocate of the importance of Pavlov's work for philosophy of mind.