People find it difficult to see when their dog is sad, scientists have found, as humans struggle to decipher their facial expressions.
Lasana Harris, a professor of social neuroscience at UCL, found that people are good at spotting anger etched on a dog’s face, but terrible at seeing sadness, and added that “puppy-dog eyes” are a myth.
Dispelling the puppy-dog eye cliche, Prof Harris says dogs cannot do it, and that the name has been wrongly adopted for what is actually a uniquely human pose.
“‘Puppy-dog eyes’ are not an expression seen in dogs or puppies, but a cultural concept to signify a more shallow sadness or regret, or as a deceptive tool to convince someone to facilitate a request,” Prof Harris, Vice-Dean International of the UCL Brain Sciences division, told The Telegraph.
“Humans are the only species with a visible sclera, the whites of the eyes. Dogs don’t have them, so the archetypical image you may find on a search engine usually has been edited to show sclera.”
The neuroscientist led two studies that involved 179 people to see if humans were better at understanding the facial expressions of dogs or chimps and bonobos.
He found that people were much better at identifying how dogs were feeling than the apes, likely as a result of millennia spent living and working together.
Five emotions were scrutinised — happiness, fear, anger, sadness, and neutral — and the researchers found that people were best at inferring “anger”; followed by “happy” and “neutral”, which did not differ; with “sadness” and “fear” equally poorly detected.
“One of the interesting findings is that people were better at spotting anger across species,” Prof Harris explained.
“An angry face looking directly at you is threatening, so people seem to have the ability to pick out this emotion best regardless of the species they are looking at as it ensures our survival.”
But while angry primates and dogs were easy to spot due to the threat of harm to the person, survival was not dependent on detecting sadness and fear, which Prof Harris says is likely why humans struggle to identify those emotions in both dogs and apes.
“A popular theory surrounding the domestication of dogs is that a lack of aggression allowed wolf-pups to enter campsites and remain with hunter-gatherer humans,” he said.
“Therefore, we pay attention to safety signals from dogs, and joy/pleasure expressions are certainly that.
“I think sadness and fear don’t hold the same evolutionary importance, and as a result, people attended to them less.”
The study found that people can tell how dogs are feeling better than they can with apes, despite the faces of a chimp and a person being far more similar than those of a dog and its owner.
People also showed an ability to get better at understanding dogs the more time they spent with them, whereas this was not seen with apes, indicating a limit to how much we can glean from a primate’s face.
“We have relationships with dogs, and none with chimps,” Prof Harris reasoned. “Moreover, we have the strongest relationship with dogs of any non-human species since dogs were the first domesticated animal and remained the only one for quite some time.
“We have not tested every species, but I would be surprised if we could better read another species’ face as well as we can read dogs. The many thousands of years we have spent in the presence of dogs gives us vastly more experience with them.”
The findings were published in the journal Scientific Reports.