Kennedy has a new puppy. When he gets home from psychology class, Kennedy turns on the television, and the puppy sits down beside him. However, within 10 minutes the dog is barking and whimpering for attention. Kennedy gives him a toy, and the barking and whimpering stop. This pattern goes on for a week, until Kennedy learns about operant conditioning in class and realises that his situation shows both positive and negative reinforcement. Why is this an example of negative reinforcement?