The baby bottle (food) is the unconditioned stimulus which leads to an unconditioned response of the baby being happy. When the baby is presented with neutral stimulus (mother), they are not bothered which is a neutral response. During conditioning, the unconditioned stimulus and the neutral stimulus (food and mum) is presented to the baby to give an unconditioned response of being happy. After conditioning, the conditioned stimulus of seeing the mum makes the baby happy which is the conditioned response