Ivan Pavlov

Ivan Petrovich Pavlov (Russian: Иван Петрович Павлов, September 14, 1849 – February 27, 1936) was a Russian, and later Soviet, 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.

http://en.wikipedia.org/wiki/Ivan_Pavlov