Ivan Pavlov developed classic conditioning by training a dog to drool to the sound of a bell as if it were food. He did this by making the dog relate the sound of the bell to food. The food was the unconditioned stimulus and drooling was the unconditioned response. This reaction was natural. Pavlov would then ring the bell independently from the food and receive no reaction from the dog. The bell is a neutral stimulus as it causes no reaction. Pavlov would then ring the bell when the dog was receiving its food.
The dog would then drool to the sound of bell. This is a conditioned stimulus and response. Stimulus Generalization occurs when the dog mistakes a different sound as the bell and produces a conditioned response. Discrimination is when the dog can distinguish between two different bell sounds. Pavlov stopped ringing the bell when the dog received its good causing the dog to forget the connection. This loss of a conditioned stimulus and response is called extinction.