PAVLOV'S EXPERIMENT

Ivan Pavlov and His Dogs

Ivan Pavlov (1849-1936) was a Russian scientist interested in studying how digestion works in mammals. He observed and recorded information about dogs and their digestive process. As part of his work, he began to study what triggers dogs to salivate. It should have been an easy study: mammals produce saliva to help them break down food, so the dogs should have simply began drooling when presented with food.
But what Pavlov discovered when he observed the dogs was that drooling had a much more far-reaching effect than he ever thought: it paved the way for a new theory about behavior and a new way to study humans.

Classical Conditioning

The people who fed Pavlov's dogs wore lab coats. Pavlov noticed that the dogs began to drool whenever they saw lab coats, even if there was no food in sight. Pavlov wondered why the dogs salivated at lab coats, and not just at food. He ran a study in which he rang a bell every time he fed the dogs. Pretty soon, just ringing a bell made the dogs salivate.
Pavlov said the dogs were demonstrating classical conditioning. He summed it up like this: there's a neutral stimulus (the bell), which by itself will not produce a response, like salivation. There's also a non-neutral or unconditioned stimulus (the food), which will produce an unconditioned response (salivation). But if you present the neutral stimulus and the unconditioned stimulus together, eventually the dog will learn to associate the two. After a while, the neutral stimulus by itself will produce the same response as the unconditioned stimulus, like the dogs drooling when they heard the bell. This is called a conditioned response. Think of an unconditioned response as completely natural and a conditioned response as something that we learn.

Classical conditioning

Classical Conditioning in Humans: The Little Albert Experiment

Pavlov demonstrated conditioning on dogs, but American psychologist John Watson wanted to prove that it happens in humans, too. He took a 9-month-old boy named Albert and showed him several items, including a white rat. Albert didn't seem scared of any of them.
The next time Watson showed the white rat to Albert, he made a loud noise by hitting a piece of metal with a hammer. Startled and scared, Albert began to cry. After many pairings of the loud noise with the rat, Albert was shown the rat without the noise. Little Albert began to cry. He had learned to associate the white rat with the loud noise and had a conditioned response to the rat.