According to Science Daily:
Like us, our canine friends are able to form abstract concepts. Friederike Range and colleagues from the University of Vienna in Austria have shown for the first time that dogs can classify complex color photographs and place them into categories in the same way that humans do. And the dogs successfully demonstrate their learning through the use of computer automated touch-screens, eliminating potential human influence.Read more about this study!
I have to say that after reading the article that we could have told them this was true, at least for Gracie. She has always picked out the pups on the TV and computer screen, and ignoring pretty much everything else!
(Credit: iStockphoto/Rami Ben Ami)