Wolves and dogs refused to continue with the experiment when only the partner got a reward.

Behaviour likely inherited from common ancestor

Dogs and wolves react to unfairness in a similar way to primates and humans, new research has found.

Until now, experts believed that a dog’s sensitivity to unfairness was likely to be an effect of domestication. But results from a new study, published in Current Biology, suggest that the behaviour is inherited.

In the study, psychologists at the University of Veterinary Medicine, Vienna, investigated the behaviour of dogs and wolves in a no-reward test and a quality test. Both species were brought into adjacent enclosures and, when asked to do so, they had to press a button with their paw to receive a reward.

“In the no-reward test, only the partner got a treat in every trial. The test animal got nothing. In the quality test, both animals got a reward, but the preferred and thus higher quality treat was again given to the partner,” explained study author Jennifer Essler. “The ability to realise this inequity became evident when they refused to continue the experiment.”

Co-author Friederike Range said that was interesting to see the animals continue when there was no partner.

“This showed that the fact that they themselves had not received a reward was not the only reason why they stopped to cooperate with the trainer,” he said. “They refuse to cooperate because the other one got something, but they themselves did not.”

In the quality test, wolves and dogs refused to continue to cooperate with the trainer and press the buzzer.

“This reaction has not been shown in experiments so far. But it confirms even more clearly that wolves and dogs really understand inequity,” said Essler. “Wolves, however, were considerably more sensitive than dogs, requiring more commands from the trainer to continue working."

Image (C) University of Veterinary Medicine, Vienna / Rooobert Bayer.