In news that will come as no surprise to anyone who has known a dog, a new study has found that dogs can tune into our emotions. Researchers found that dogs use information from different senses to read us, an ability that has previously only been observed in humans.
For the study, 17 domestic dogs were shown large projected pairs of images from the same person or dog exhibiting two different expressions: happy/playful and angry/aggressive. At the same time, the dogs heard a bark or human voice that matched the emotional tone of one of the images.
The researchers found the the dogs spent significantly longer looking at the image that matched the sound. If the human voice sounded happy, for example, the dogs' attention lingered on the happy human photo. If the dog bark sounded aggressive, the dogs looked longer at the angry dog image.
"Previous studies have indicated that dogs can differentiate between human emotions from cues such as facial expressions, but this is not the same as emotional recognition," said researcher Dr. Kun Guo, from the University of Lincoln.
"Our study shows that dogs have the ability to integrate two different sources of sensory information into a coherent perception of emotion in both humans and dogs. To do so requires a system of internal categorization of emotional states. This cognitive ability has until now only been evidenced in primates and the capacity to do this across species only seen in humans."
Co-author Professor Daniel Mills, from the School of Life Sciences at the University of Lincoln, said: “It has been a long-standing debate whether dogs can recognise human emotions. Many dog owners report anecdotally that their pets seem highly sensitive to the moods of human family members.
"However, there is an important difference between associative behavior, such as learning to respond appropriately to an angry voice, and recognising a range of very different cues that go together to indicate emotional arousal in another. Our findings are the first to show that dogs truly recognize emotions in humans and other dogs."
The study was performed by a team of animal behavior experts and psychologists from the University of Lincoln, U.K., and University of Sao Paulo, Brazil. It was published in the Royal Society journal Biology Letters.
An earlier study
Several years ago, in the first study to compare brain function between humans and a nonprimate animal, researchers found that man’s best friends have dedicated voice areas in their brains, just like us. And according to the news release, in the same way we are sensitive to the acoustic cues of emotion, so are they.
The findings offer fresh a perspective into the unique alliance between humans and our canine companions. Further, it helps shed light on the behavioral and neural mechanisms that have made this relationship so strong throughout many millennia.
"Dogs and humans share a similar social environment," says Attila Andics of MTA-ELTE Comparative Ethology Research Group in Hungary. "Our findings suggest that they also use similar brain mechanisms to process social information. This may support the successfulness of vocal communication between the two species."
The research team used 11 dogs that had been trained to lay still in an fMRI brain scanner, allowing the researchers to run the same neuroimaging experiment on both dog and human participants. (This was a first.) They played nearly 200 dog and human sounds — from playful laughs and barks to whining and crying — and captured both dogs' and humans' brain activities throughout.
The results show that dog and human brains include voice areas in similar locations. In both groups, an area near the primary auditory cortex lit up more with happy sounds than unhappy ones. Andics says they were most struck by the common response to emotion across species.
But before you replace your therapist with your dog, you should know there were differences, too. In dogs, almost half of all sound-sensitive brain regions responded more strongly to sounds rather than voices. In humans, only 3 percent of sound-sensitive brain regions showed greater response to sounds rather than voices.
Nonetheless, the findings confirm what many of us already know — and it’s a great step in understanding why dogs seem so remarkably empathetic to their owners or the other people they spend time with.
"This method offers a totally new way of investigating neural processing in dogs," Andics says. "At last we begin to understand how our best friend is looking at us and navigating in our social environment."