Joe eventually develops and shows excitement and joy to the bell's sound because of the conditioned stimulus that led to a conditioned response. His mother hugging after him after entering the house after ringing the bell is a conditioned stimulus. Eventually, Joe develops interest and joy in the bell sound due to repeated bell ringing serving as a conditioned stimulus. Therefore the excitement and joy after the bell ring is a conditioned response. Joe's mother hugging him and ringing the bell after coming from work remains a conditioned stimulus that develops excitement and joy towards the bell sound after his mother ringing the bell, which stands as a conditioned response that always occurs after Joe mother rings the bell.