A Science Odyssey
People and Discoveries

Ivan Pavlov
1849 - 1936

Ivan Pavlov was born in a small village in central Russia. His family hoped that he would become a priest, and he went to a theological seminary. After reading Charles Darwin, he found that he cared more for scientific pursuits and left the seminary for the University of St. Petersburg. There he studied chemistry and physiology, and he received his doctorate in 1879. He continued his studies and began doing his own research in topics that interested him most: digestion and blood circulation. His work became well known, and he was appointed professor of physiology at the Imperial Medical Academy.

The work that made Pavlov a household name in psychology actually began as a study in digestion. He was looking at the digestive process in dogs, especially the interaction between salivation and the action of the stomach. He realized they were closely linked by reflexes in the autonomic nervous system. Without salivation, the stomach didn't get the message to start digesting. Pavlov wanted to see if external stimuli could affect this process, so he rang a metronome at the same time he gave the experimental dogs food. After a while, the dogs -- which before only salivated when they saw and ate their food -- would begin to salivate when the metronome sounded, even if no food were present. In 1903 Pavlov published his results calling this a "conditioned reflex," different from an innate reflex, such as yanking a hand back from a flame, in that it had to be learned. Pavlov called this learning process (in which the dog's nervous system comes to associate the sound of the metronome with the food, for example) "conditioning." He also found that the conditioned reflex will be repressed if the stimulus proves "wrong" too often. If the metronome sounds repeatedly and no food appears, eventually the dog stops salivating at the sound.

Pavlov was much more interested in physiology than psychology. He looked upon the young science of psychiatry a little dubiously. But he did think that conditioned reflexes could explain the behavior of psychotic people. For example, he suggested, those who withdrew from the world may associate all stimulus with possible injury or threat. His ideas played a large role in the behaviorist theory of psychology, introduced by John Watson around 1913.

Pavlov was held in extremely high regard in his country -- both as Russia and the Soviet Union -- and around the world. In 1904, he won the Nobel Prize in physiology/medicine for his research on digestion. He was outspoken and often at odds with the Soviet government later in his life, but his world renown, and work that his nation was proud of, kept him free from persecution. He worked actively in the lab until his death at age 87.

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