A specialized trait previously thought to exist only in humans and primates has been found in dogs too. Researchers from the Faculty of Veterinary Medicine at the University of Helsinki, Finland said that dogs have the ability to recognize familiar faces including its owner's just by looking at their photographs.

For the study, the researchers tracked their eye movements while they watched a series of familiar and unfamiliar images of humans and dogs on the computer screen.

"Dogs were trained to lie still during the image presentation and to perform the task independently. Dogs seemed to experience the task rewarding, because they were very eager to participate" Researcher Outi Vaino said in statement.

The researchers found that the dogs stared longer at images of familiar faces and eyes when compared to the stranger ones. This finding indicates that dogs do possess facial recognition skills, similar to humans.

The researchers also found that dogs gazed at images of dogs longer than that of humans, irrespective of their familiarity. This finding supports a previous study that found that dogs prefer viewing conspecific faces (images belonging to the same species) when compared to others.

Some of the images were shown in inverted forms. The researchers found that dogs looked at upright faces as long as inverted faces. But the dogs focused their attention more on the eye area of the upright faces like humans.

"This study shows that the gazing behavior of dogs is not only following the physical properties of images, but also the information presented in the image and its semantic meaning," Researcher Outi Vaino wrote.

The study has been published in the journal Animal Cognition. This is the first study that has analyzed the eye movement patterns to determine the facial recognition ability of dogs.