Dogs Know That Smile on Your Face
Our dogs comfort us when we feel sad or upset, but did you know that they can tell the difference between an angry or happy face?
According to a recent study published in the Cell Press Journal Current Biology, February 12, 2015, Dr Corsin Muller and colleagues from the University of Veterinary Medicine, Vienna found that dogs could tell the difference between happy and angry human faces. This proves to be the first solid evidence that an animal, other than a human, can distinguish between different emotions in another species.
Muller and colleagues went about this research by training dogs to distinguish between images of the same person either showing a happy or angry face. The dog breeds in this research included Border Collies, a Fox Terrier, a Golden Retriever, a German Shepherd and some mixed breeds. All the dogs tested were taught how to use a touchscreen, and had to touch either a happy or an angry face before they could be rewarded with a treat.
Results demonstrate that in all cases, dogs were able to distinguish between both a happy or an angry face. In the study they were given images of only the upper or the lower part of a human face. They were trained with 15 picture pairs, and the dogs’ discriminatory abilities were then tested during four trials. These four trials included images of:
- the same half of faces previously shown during training, yet the faces shown to the dogs were new ones.
- the other half of the human faces used during the training process.
- the other half of new faces
- the left half of human faces used during training. In past studies it was demonstrated that dogs prefer to look at this side of the human face.
According to this research paper, the dogs were able to distinguish between a happy or a sad human face. The researchers found that the choice was made more often than would occur by random choice in every test. These findings demonstrate that dogs are able to learn how to identify human facial expressions, and that they were also able to transfer what they learned in training to new cues given to them throughout the training sessions.
“We think our dogs in our study could have solved the task only by applying their knowledge of emotional expressions in humans to the unfamiliar pictures we presented to them,” adds Dr. Muller.
Previous attempts have been made to see whether dogs could tell the difference between human emotional expressions, yet none of them were totally convincing. Dr. Ludwig Huber, senior author and head of the group at the University of Veterinary Medicine Vienna’s Messerli Research Institute, says that it’s hard to say what the exact meanings are for dogs, but that “it appears likely to us that the dogs associate a smiling face with a positive meaning, and an angry facial expression with a negative meaning.”
According to the research paper both Huber and Muller indicate that the dogs were slower learning to associate an angry face with a reward, than a happy face with a reward. They suggest that this indicates that the dogs already had an idea, based on previous experience, that it was in their best interest to stay away from people that look angry.
Both researchers will continue to explore how past experiences in a dog’s life affects his or her ability to recognize human emotion. They also want to study how dogs themselves express all these emotions, and how these canine emotions are influenced by the emotions of their pet parents and handlers. According to an interview with National Geographic, Muller believes that it is by experiencing things that dogs would be able to tell whether someone was angry or happy.
“ We expect to gain important insights into the extraordinary bond between humans and one of their favorite pets, and into the emotional lives of animals in general,” adds Muller. He also wants to examine whether the domestication of dogs has played a role in whether they’re able to discriminate between an angry and a happy face.
For more information visit: cell.com/current-biology/abstract/S0960-9822(14)01693-5
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