When it comes to understanding the feelings and behaviors of your pets, it helps to keep in mind that they have a sense of fairness. Studies have shown this in dogs, birds, and other animals. It’s a good bet that cats will have a sense of fairness, too. So if one dog is allowed on the couch and the other isn’t, keep that in mind when you are wondering what happened to your slippers.
This was clipped out of recent TED talk given by Frans de Waal regarding moral behavior in animals. In a nut shell we get to observe reaction and response of two Capuchin monkeys when they receive different rewards for the same type of work.