Dogs can sort photographs into categories, in the same way that humans and other primates do, the British weekly New Scientist says.

Researchers at the University of Vienna say they were able to train four canines to distinguish photographs that featured dogs from photographs that did not.

At first, the pooches were simultaneously shown photographs of a landscape and of a dog, and were rewarded if they selected the latter, using a paw-operated computer touch screen, the study said.  The dogs were then shown an unfamiliar landscape and dog photos. They continued to correctly identify the pictures with the dog.

In the final phase of the experiment, the dogs were shown an unfamiliar dog that was superimposed on a landscape that had been used in the training phase.  The animals were still able to pick out the dog in preference to an image of just a landscape.

Scientists say this study is proof that dogs have reasoning abilities.

“We know they can categorise ‘food’ or ‘enemies’ from experience,” said Friederike Range, the leader of the study. “But this is the first time we’ve taught them an abstract concept—‘a dog’—and shown they can transfer this knowledge to a new situation.”