Figure 4.1 | The Elements of Classical Conditioning | In classical conditioning, you start with a reflex—an unconditioned stimulus (UCS) that automatically elicits an unconditioned response (UCR). To condition a new response to a neutral stimulus, the neutral stimulus is presented just before the unconditioned stimulus. After several pairings, the neutral stimulus elicits a new response called the conditioned response (CR). The neutral stimulus is now referred to as the conditioned stimulus (CS).