Ivan Petrovich Pavlov

Ivan Petrovich Pavlov (September 14, 1849 – February 27, 1936) was a Russian, and later Soviet, physiologist psychologist, and physician.

He discovered that he could train a dog to know when he was about to eat. He figured out that when the dog heard the fottsteps he started drooling because he knew he was going to eat. Then Pavlov inserted tubes at the sides of the dogs mouth so he could observe when the dog started drooling. Then he used other objects to disguise the fottsteps, and the dog would drool.

For example If a bell was sounded in close association with the meal, the dog learnt to associate the sound of the bell with food. After a while, at the mere sound of the bell, the dogresponded by drooling.