Ivan Pavlov made many discoveries related to animals in his lifetime, one of them being the discovery of the conditioned response, a reflex that occurs in most animals. He experimented right in his own home this theory. He noticed they would drool every time they saw food (linked events). Then, he began to try to link other events to drooling. He rang a bell every time he served them food, and this manipulated them in such a way that they would link the sound of a bell to salivation.