Ivan Pavlov is best known for his studies on the digestive systems which consequently led to the discovery of conditioned reflexes making it possible to study a purely physical reaction to an outside stimulus. His other major fields of study include research on the cardiovascular and nervous systems. I. M. Sechenov and his 1863 book Reflexes of the Brain were strong influences in Pavlov's life. Sechenov hypothesized about physical reflexes and their relation to psychic activity. This idea was the foundation upon which Pavlov based his experiments. Dogs were Pavlov's experimental animals, used in his research on the physiology of digestion that earned him a Nobel Prize in 1904. He noticed that when hungry dogs were presented with the thought of food, provoked by sight, sound, or smell, the dogs would salivate and produce gastric secretions, thus producing a physical response to external stimulus or a conditioned reflex. There was...