Dogs recognize facial cues like smiles and scowls

Your dog gets you. It's science.
Actually, dogs can get you -- as well as almost any other human -- but it takes training. A new study shows that dogs can learn through experience to recognize facial expressions and differentiate between outwardly expressed emotions.
Animals and humans are, of course, naturally predisposed and trained to recognize emotional cues among their own kind. Recognizing facial cues and emotional expressions in other species, on the other hand, is more complicated. But not so complicated that a dog can't learn how to do it.
In an experiment conducted by animal psychologists at the University of Vienna, in Austria, researchers trained dogs to respond to various emotional expressions. The study's canine participants were taught to respond to both happy and angry faces. Some dogs were shown only the top halves of faces, while other dogs were shown only the bottom halves.
After the response was well ingrained, dogs were shown a new round of images. The stimuli were four types: new faces (different people) exhibiting the same expressions; the other half of previously used faces; the corresponding halves of the new faces; and/or only left half of previously used faces.
Dogs were able to recognize the emotional cues as trained using all four types of stimuli. The results proved that the canines could use their training to recognize previously unseen tops and bottom halves of faces, as well as project their understanding of emotional cues onto new faces.
"We can rule out that the dogs simply discriminated [between] the pictures based on a simple salient cue, such as the visibility of teeth," study author Corsin Muller, an animal behavior researcher at the University of Veterinary Medicine Vienna, told LiveScience. "Instead, our results suggest that the successful dogs realized that a smiling mouth means the same thing as smiling eyes."
Although the study doesn't purport to explain why dogs have this ability, researchers say it's clear centuries of cohabitation has something to do with it.
"I would expect this ability in other species pairs, such as domestic species in close relationships to humans, but also in animals in zoos or sanctuaries," co-author Ludwig Huber told Wired. "I would be surprised if enculturated great apes would not be able to solve the task we presented to the pet dogs. In my opinion, every animal that lives somehow in a close relationship to another species that shows clear emotional expressions should be able to encode them with enough experience."
The new research was published this week in the journal Current Biology.