First, Pavlov used soundproof lab because it allowed to isolate experimenters from all extraneous stimuli during the experimental procedures. Second, Pavlov chose food as unconditioned stimulus because food will elicit the unconditioned response, which was the salivation of the dog. In order to find a neutral stimulus that was completely unrelated to food, Pavlov decided to use the metronome as the neutral stimulus . The ticking of the metronome was exposed to the dog, immediately followed by the food. After numerous trials under this condition, the dog has began to salivate after hearing the ticking of the bell. In another word, the metronome has changed from neutral stimulus to conditioned stimulus , which has created the conditioned response of dog's salivation. Pavlov and his assistants also elaborated on this preliminary finding by using different unconditioned and neutral stimuli. For example, the odor of vanilla was presented after a mild acid solution (similar to lemon juice) was placed in the dog's mouth . The mild acid solution caused the dog to salivate . However, after several trials, the dog began to salivate solely to the odder of vanilla . Another importance finding was that the neutral stimulus did not affect the subjects conditioning if it was presented after the unconditioned stimulus. Pavlov first gave the mild acid solution to the dog; and after awhile, presented the odor of vanilla . But there was no significant change of the dog's behavior. The odor of vanilla did not changed to a conditioned stimulus. he theory of Classical Conditioning (aka Pavlovian conditioning) has now been accepted universally and unchanged since its first finding through Pavlov's work. It is now used to explain various different human behaviors, such as causation of phobias, why people dislike certain food, source of emotions, etc. Pavlov's finding has showed that classical conditioning focuses on reflexive behaviors,…