If you've ever imagined what it would be like if your dog could talk, add another phrase to his or her imaginary phrase book—"Hey, no fair!"—because recent evidence suggests that dogs do have a sense of fairness and equality.
In an experiment that gets you wondering just how long it will be before dogs form trade unions, researchers at the Clever Dog Lab at the University of Vienna, Austria, discovered that dogs share a characteristic with primates (such as humans) when faced with inequity. Pairs of familiar dogs were trained to "shake hands" for a food reinforcer. When one dog received a reward for this behavior, but the other did not, the dog who had not been rewarded would tend to "go on strike!"
There were behavioral differences in dogs tested without a food reward in the presence of a rewarded partner compared to both a baseline condition, where both partners were rewarded, and an asocial control situation, where there was no reward and no partner present.
Interestingly, dogs did not seem to care if another dog received a more valuable reward for the same behavior. This is in contrast to primates, who in similar experiments do appear to mind if their partner gets a better reward than them for performing the same behavior.