Ivan Pavlov was a late 19th and early 20th century Russian physiologist best known for his research into conditioned reflexes. 

Professional Life

Ivan Pavlov was born in 1849 in Ryazan, Russia. He was originally enrolled in seminary, but because of his strong scientific interests, he changed direction and began to pursue science. He attended the University of St. Petersburg and studied physiology and chemistry, graduating in 1875.

Pavlov continued his education at the Military Medical Academy, where he earned his medical degree in 1879 and a Gold Medal for his doctoral dissertation in 1883. In his thesis, he explored theories of “nervism” and reflex patterns. Pavlov worked as a professor at the Military Medical Academy from 1895–1925; he also became director of the department of physiology at the Institute of Experimental Medicine in 1895. Pavlov researched the physiology of the digestive system, for which he was awarded the Nobel Prize for Physiology or Medicine in 1904.

Later in life, Pavlov became an outspoken critic of the Soviet government. His fame, however, provided some protection from persecution.

Pavlov married Seraphima Vasilievna Karchevskaya in 1881. They had five children, though the first died early in childhood. Pavlov died of pneumonia in 1936. 

Contribution to Psychology

Pavlov began examining the reflex system while studying the gastric systems of dogs. He studied the digestive system in earnest, and looked to determine the effects of nerves on digestive organs. He later studied the reflex system in relation to pain and stress. He realized that subjects often responded in the same way to different stimuli, regardless of their temperament. Carl Jung and William Sargant continued Pavlov’s theories by researching human temperament types.

Pavlov is best known for his classical conditioning study, also known as Pavlovian conditioning, as published in Conditioned Reflexes in 1926. He developed this theory with Ivan Filippovitch Tolochinov, his assistant, in 1901. They found that when a bell was closely associated with the delivery of food, a dog would begin to salivate when the bell was rung. The bell served as a conditioned stimulus, which elicits a conditioned reflex. Salivating in response to food alone, by contrast, is an unconditioned reflex to an unconditioned stimulus. The experiments that Pavlov conducted on the salivating dogs have become recognized throughout common culture with the term “Pavlov’s Dogs.”

Pavlov's research into classical conditioning began to lay the foundation for the field of behaviorism and comparative psychology, and conditioning techniques are still used in behavior modification. For example, one highly popular form of dog training, called clicker training, conditions a dog to respond to a clicker as if it is a food reward.

Although he was best known for his work in conditioning, Pavlov also developed the theory of transmarginal inhibition. Transmarginal inhibition provides a gauge of a person or non-human animal's response to overwhelming, and often painful, stimuli. Pain tolerance varies between species and among individuals, and Pavlov found that all organisms ultimately reached a “shut-down point.” He believed an organism's shut-down point could provide important information about its nervous system, and argued that there are three stages to TMI: 

  1. Equivalency phase, during which an organism's response is proportional to the stimuli. For example, someone who stubs his or her toe might yelp and quickly recover.
  2. Paradoxical phase, during which insignificant stimuli elicit exaggerated responses, while significant stimuli result in muted responses. For example, a child might scream in pain in response to a paper cut but seem unaware of a broken bone. 
  3. Ultra-paradoxical response, which occurs when negative stimuli elicit a positive reaction. 

He also found that a certain percentage of the population qualified as “highly sensitive persons,” whose reaction to stimuli seemed disproportionate.


  1. Ivan Pavlov - Biographical. (n.d.). NobelPrize.org. Retrieved from http://www.nobelprize.org/nobel_prizes/medicine/laureates/1904/pavlov-bio.html
  2. Ivan Petrovich Pavlov. (2008). Notable Scientists from 1900 to the Present. Retrieved from http://www.gale.cengage.com/InContext/bio.htm