A new study claims that your canine companion can tell if you look angry or content, confirming the suspicions of dog owners around the world.

A group of 11 dogs were trained to recognize an angry or happy face using images of the same person. Only the upper or lower half of the person’s face was shown during the training phase. Researchers then tested whether the dogs could recognize the same emotions in different images of various human faces, and found that the dogs correctly chose the angry or happy face more often that random chance would predict.

Dogs Can Distinguish Angry Or Happy Human Faces [STUDY]

Complex canine test

“We can rule out that the dogs simply discriminated [between] the pictures based on a simple salient cue, such as the visibility of teeth,” said Corsin Müller, study author and animal behavior researcher at Messerli Research Institute at the University of Veterinary Medicine, Vienna.

“Instead, our results suggest that the successful dogs realized that a smiling mouth means the same thing as smiling eyes,” while an angry mouth and angry eyes follow the same principle, he said.

Of the 24 dogs originally recruited for the study, only 11 of them actually completed the experiment. The other 13 dropped out for various reasons before training could begin.

Why can dogs recognize human expressions?

Older research had already shown that dogs could read the expressions of people they are familiar with, even if only part of the face is visible. Another study had previously tried to prove whether dogs could differentiate between human expressions or not, but no conclusion was reached.

“With our study, which was inspired by these previous attempts, we think we can now confidently conclude that at least some dogs can discriminate human facial expressions,” Müller told Live Science.

The researchers still do not fully understand why dogs would have developed this ability, but they postulate that the “most likely explanation appears to be that the basis lies in the life-long co-habitation of the dogs with humans, during which the dogs get a lot of exposure to human facial expressions,” which Müller said has provided them with a lot of learning opportunities.

The full study can be found in the journal Current Biology, where it was published on February 12.