Any dog owner will tell you his dog understands what he’s feeling—and now, science backs him up: A new study confirms that dogs know when people feel happy or angry, and that they can understand the difference between the two.
“Our study demonstrates that dogs can distinguish angry and happy expressions in humans,” Ludwig Huber, coauthor of the paper in Current Biology and researcher at University of Veterinary Medicine Vienna’s Messerli Research Institute, said in a press release. “They can tell that these two expressions have different meanings, and they can do this not only for people they know well, but even for faces they have never seen before.”
To understand whether dogs could decipher facial expressions, Huber and his team trained the pups to identify either happiness or anger by studying pictures. The canines looked at the faces of 15 different people, but not their whole faces—just half, to see if the dogs could understand emotions by simply looking at the eyes or the mouth. Half of the dogs received a treat when they identified the happy faces, and half the dogs received a treat for finding the angry face.