Theory of Classical Conditioning was first introduced by a Russian physiologist Ivan Pavlov in 1927. Pavlov was interested in knowing about the role of nerves in the digestion system of mammals. He used dogs as subjects in his study. When experimenting with dogs, he fitted a tube in the salivary gland of a dog for observing the production of saliva in its mouth. Pavlov first noted that saliva was automatically produced in the mouth of a dog, simply at the time of eating food. He termed this behavior, the production of saliva, of a dog as unlearned or unconditioned response to an unconditioned stimulus, food. However, after some time, he noted that the dog started producing saliva merely by seeing Pavlov’s lab assistant who used to serve food to it. Pavlov was astonished by this change in the dog’s behavior. He discovered that the same behavior, production of saliva, could be elicited from the dog by using some other stimulus instead of the food. Pavlov began to use a bell as a stimulus for this purpose. He named the bell as a neutral stimulus, which by itself had no role in the elicitation of saliva. However, when he started ringing the bell before presenting the food to the dog, the dog began to associate the sound of a bell with the presentation of food, so it began to produce saliva merely by hearing the sound of a bell. Pavlov termed this response of a dog as a conditioned response. The dog behaved, produced saliva, in this way because it learned that it would be served food just after the ring of a bell. Therefore, it conditioned the production of saliva with the ring of a bell.
Pavlov generalized his findings for human being and concluded that human’s behaviors are the results of various stimuli, which are present in our environment. He also discovered that we could control human’s behavior by using different stimuli simply by pairing them with each other.
