Medicine in stamps. Ivan Petrovich Pavlov (1849-1936): conditioned reflexes.

Pavlov is famous for demonstrating that once conditioned, a dog’s digestive system can respond to the simple ringing of a bell without the actual introduction of food. The phenomenon was termed conditioned reflex, and it won for this Russian physiologist the Nobel Prize in 1904. Secrecy and poor communication led to his premature obituary in the Western media in 1916. Pavlov, in fact, worked on for an additional twenty years as one of the Soviet Union’s leading scientists.