Not only dogs recognize faces in photographs, but they can also recognize the expression of human emotion, scientists announced recently.
“It had been unknown that dogs could recognize human emotions in this way,” said Ludwig Huber from the Messerli Research Institute, University of Veterinary Medicine, Vienna, Austria.
For the study, scientists presented photos of happy and angry faces placed side by side to 20 dogs.
In a previous phase of the study, dogs from one group were trained to indicate the images of happy faces, while the other group received rewards for recognizing angry faces.
Researchers ripped the images horizontally, allowing the dogs to see either only the eye region or only the mouth region during the training phase – this removed the possibility that animals were making decisions based on facial features such as frown lines.
Most of the dogs learned to separate happy and angry faces using the face halves. Later, dogs were able to isolate the mood of a person in new photos as well in face halves they have not seen during the training phase.
Dogs who were trained to pick of happy faces performed much better compared with dogs trained for selecting angry faces.
“It seems that dogs dislike approaching angry faces,” Huber explained.
The study will be published in the journal Current Biology.