Who was Ivan Pavlov?
The Russian scientist Ivan Petrovich Pavlov was born in 1849 in Ryazan, where his father worked as a village priest. In 1870 Ivan Pavlov abandoned the religious career for which he had been preparing, and instead went into science. There he had a great impact on the field of physiology by studying the mechanisms underlying the digestive system in mammals. For his original work in this field of research, Pavlov was awarded the Nobel Prize in Physiology or Medicine in 1904. By then he had turned to studying the laws on the formation of conditioned reflexes, a topic on which he worked until his death in 1936. His discoveries in this field paved the way for an objective science of behavior.
Pavlov's drooling dogs
While Ivan Pavlov worked to unveil the secrets of the digestive system, he also studied what signals triggered related phenomena, such as the secretion of saliva. When a dog encounters food, saliva starts to pour from the salivary glands located in the back of its oral cavity. This saliva is needed in order to make the food easier to swallow. The fluid also contains enzymes that break down certain compounds in the food. In humans, for example, saliva contains the enzyme amylase, an effective processor of starch. Pavlov became interested in studying reflexes when he saw that the dogs drooled without the proper stimulus. Although no food was in sight, their saliva still dribbled. It turned out that the dogs were reacting to lab coats. Every time the dogs were served food, the person who served the food was wearing a lab coat. Therefore, the dogs reacted as if food was on its way whenever they saw a lab coat. In a series of experiments, Pavlov then tried to figure out how these phenomena were linked. For example, he struck a bell when the dogs were fed. If the bell was sounded in close association with their meal, the dogs learnt to associate the sound of the bell with food. After a...