A team of cognitive scientists at the University of Veterinary Medicine Vienna has demonstrated for the first time that dogs can differentiate between happy and angry human faces. Dogs may have developed this skill due to their close relationship with people, in which the animals have learned to understand certain aspects of human non-verbal communication. The results will be published in the journal Current Biology.
Dogs can discriminate human faces in pictures. This was demonstrated by Ludwig Huber and colleagues at the Messerli Research Institute in 2013.
But are dogs also able to discriminate human emotional expressions? To date, no study could answer this question convincingly.
Dogs discriminate human emotions on a touchscreen
Corsin Müller and Ludwig Huber from the Messerli Research Institute investigated this skill together with colleagues at the Clever Dog Lab at the Vetmeduni Vienna. They presented photos of happy and angry women's faces side by side on a touchscreen to 20 dogs.
During the training phase, dogs from one group were trained to touch images of happy faces. The other group was rewarded for choosing angry faces.
To exclude the possibility that the animals were making their decisions based on conspicuous differences between the two pictures, such as teeth or frown lines, the researchers split the images horizontally so that during the training phase the dogs saw either only the eye region or only the mouth region. Most of the dogs learned to differentiate between the happy and angry face halves. They subsequently also managed to identify the mood in novel faces as well as in face halves that they had not seen during the training phase.
Approaching happy faces is easier
Dogs trained to choose the happy faces mastered the task significantly faster than those who had to choose the angry faces. "It seems that dogs dislike approaching angry faces," study director Ludwig Huber explains.
"We believe that dogs draw on their memory during this exercise. They recognize a facial expression which they have already stored," first author Corsin Müller explains. "We suspect that dogs that have no experience with people would perform worse or could not solve the task at all."
Dogs' visual abilities are underestimated
Dogs have a much better sense of smell and hearing than humans, but the spatial resolution of their vision is about seven times lower. "It had been unknown that dogs could recognize human emotions in this way. To better understand the development of these skills, we want to perform similar tests also with wolves at the Wolf Science Center," Huber says.
As part of the WWTF project "Like me," the team led by Ludwig Huber has spent the past three years investigating whether dogs are able to understand the emotions of conspecifics or of people. Project partners at the University of Vienna and the Medical University Vienna are performing similar research on the empathic abilities of people.
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