Dogs feel envy and reject unequal treatment

Dogs can feel a simple form of envy and will respond with petulance to unequal treatment, a study has found. But while dogs will refuse to give their paw when they see another dog is given a treat for doing it and they are not, they do not seem to care whether the other dog gets a better treat.

And unlike monkeys - who in previous experiments got so frustrated with the unequal treatment that they refused to eat the less tasty treat - the dogs never rejected a snack. Researchers believe that sensitivity to being treated unequally is a critical element in the evolution of social cooperation and until recently it was believed that only humans were capable of this behaviour.

Austrian researchers believed that this may also occur in dogs because they engage in complex and elaborate cooperation with humans and show a high sensitivity to human behaviour. They conducted an experiment in which they monitored how 29 dogs responded to a request to put their paw in the experimenter's hand when they were alone or sitting next to another dog.



If the dogs saw that their partner was getting a treat for giving the paw and they were not, they soon refused to give their paw and would even go so far as to look away from the experimenter. But they did not seem to care if they were only given bread after the other dog was given sausage, the study published in the Proceedings of the National Academy of Sciences found.

"It was not the presence of the second dog but the fact that the partner received the food that was responsible for the change in the subjects' behaviour," wrote lead researcher Friederike Range of the University of Vienna.

"The fact that the subjects refused earlier and hesitated longer to obey the command to give the paw to the experimenter when the partner received a reward but they themselves did not ... suggests that dogs are sensitive to an unequal reward distribution."