Discrimination is a term that is used in both classical and operant conditioning. In classical conditioning, it refers to an ability to distinguish between a conditioned stimulus (CS) and other, similar stimuli that don't signal an unconditioned stimulus (US). For example, if Pavlov's dog had developed discrimination, it would have salivated to the tone that had been paired with the delivery of the meat powder, and not a similar tone with a slightly different pitch. In operant conditioning, the definition is essentially the same, but here the organism discriminates between a learned, voluntary response and an irrelevant, non-learned response. For example, a dog that has learned to sit when a person says "sit" in order to receive a treat, but the dog does not sit when a person says "bit".