The unconditioned stimulus is the stimulus that elicits a natural and unlearned response. For example, the child does not have to learn to feel pain from the shot. A dog does not have to learn to feel pleasure when fed. The conditioned stimulus is a formerly neutral stimulus that now elicits a response through its pairing with the conditioned stimulus. The perfume that the child associates with his grandmother is a conditioned stimulus. The doctor that the child associates with the shot is also a conditioned stimulus.