Dogs and Human Emotions

Recognizing the facial expressions of others within your own species is an important tool in communication and, well, survival. But what about in other species?

For domesticated dogs, understanding human facial expressions and emotions is vital to their survival, too. Researchers recently published two papers about the canine ability to read human faces and understand our emotions—traits rarely seen outside of our own species.

The first study, published last week in PLoS ONE, describes how dogs view facial expressions systematically, preferring eyes. Specific facial expressions alter their viewing behavior, especially in the face of threat. The Finnish research team showed images of both dogs and humans to 31 dogs of 13 different breeds and found that the viewers looked first at the eye region and generally examined eyes longer than nose or mouth areas. If the photograph displayed a threatening dog, the viewing dog would then look at the screen animal’s mouth; if the picture displayed a threatening human, however, the viewing canine would avoid looking at the face altogether. “Domestication may have equipped dogs with a sensitivity to detect the threat signals of humans and respond to them with pronounced appeasement signals," says lead author Sanni Somppi from the University of Helsinki.

The second study, published last week in Current Biology, determined that dogs can recognize emotions in humans by combining information from different senses—taking into account both visual and auditory cues. Scientists presented 17 domestic dogs with pairings of images and vocal sounds conveying different combinations of positive (happy or playful) and negative (angry or aggressive) emotional expressions in humans and dogs. The dogs spent significantly longer looking at the facial expressions that matched the emotional state of the vocalization, for both human and canine subjects.

The team believes that dogs must form abstract mental representations of the different emotional states, and are not simply displaying learned behaviors when responding to the expressions of people and other dogs. “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,” says co-author Kun Guo of the University of Lincoln. “To do so requires a system of internal categorization of emotional states.” According to Guo, until now, only primates (including humans!) were known to have this cognitive ability.

“Our findings are the first to show that dogs truly recognize emotions in humans and other dogs,” continues co-author Daniel Mills. “As a highly social species, such a tool would have been advantageous, and the detection of emotion in humans may even have been selected for over generations of domestication by us.”

Image: Bryan Casteel/Flickr