Your pet dog can recognise your photo from a variety of other pictures by tracking or looking at your eyes, a new study has found, suggesting the canines may have facial recognition skills similar to humans.

So far the specialised skill for recognising facial features holistically has been assumed to be a quality that only humans and possibly primates possess.

Although it is known that faces and eye contact play an important role in the communication between dogs and humans, this was the first study where facial recognition of dogs was investigated with eye movement tracking, scientists say.

Typically animals' ability to discriminate different individuals has been studied by training the animals to discriminate photographs of familiar and strange individuals.

The researchers, led by Professor Outi Vainio at the University of Helsinki, tested dogs' spontaneous behaviour towards images - if the dogs are not trained to recognise faces are they able to see faces in the images and do they naturally look at familiar and strange faces differently?

"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," said Vainio.

Dogs' eye movements were measured while they watched facial images of familiar humans and dogs being displayed on the computer screen. As a comparison, the dogs were shown facial images from dogs and humans that the canines had never met.

The results indicate that dogs were able to perceive faces in the images. Dogs looked at images of dogs longer than images of humans, regardless of the familiarity of the faces presented in the images.

The pooches fixed their gaze more often on familiar faces and eyes rather than strange ones, ie dogs scanned familiar faces more thoroughly.

In addition, part of the images was presented in inverted forms ie upside-down. The inverted faces were presented because their physical properties correspond to normal upright facial images.

It is known that the human brain process upside-down images in a different way than normal facial images.

Dogs viewed upright faces as long as inverted faces, but they gazed more at the eye area of upright faces, just like humans.

This study shows that the gazing behaviour of dogs is not only following the physical properties of images, but also the information presented in the image and its semantic meaning.

Dogs are able to see faces in the images and they differentiate familiar and strange faces from each other.