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Does Your Dog Know When You’re Sad? Studies Say Yes (Sort Of)

Your dog can recognize your expressions, from anger to joy.

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Dogs are symbols of loyalty and faithful companionship. Though we don’t need studies to tell us that dogs can understand human emotion, it’s still surprising to learn that our pups can literally read the expressions on our face.

The skill is especially surprising given the difference between human and canine brains. For human beings, faces are central to visual communication, and our brains have specialized regions that are programmed to respond to faces. Dogs’ brains, on the other hand, lack this face-sensitive region. Even so, according to research by ethologists and neuroscientists at Eötvös Loránd University in Hungary published in October 2020 in the Journal of Neuroscience, dogs do attend to faces, read emotion from faces, and recognize people from the face alone. “But other bodily signals seem to be similarly informative for them,” says Eszter Borbála Farkas, PhD, a member of the research team.

When Human and Dog Brains Align

To explore how dogs and humans respond to visual information about others, the Hungarian team, with help from labs in Mexico, tested 20 dogs and 30 humans in the same functional magnetic resonance imaging (fMRI) experiment while they were awake and unrestrained. The dogs were trained to lie still inside an MRI tube — no mean feat! — their heads resting as they watched images on the screen. Both human and canine subjects viewed four types of 2-second videos depicting the front or back of a human head, and the front or back of a dog’s head.

The scientists found that while the dogs lacked those face-sensitive brain regions, they did possess specialized circuitry that lit up when they were shown the image of another dog. In other words, dog brains preferred images of individuals from their own species over images of humans, no matter how attached they otherwise were to their human family and friends.

This boils down to the fact that although faces may be of crucial importance to humans, not all animals see them in the same light. Instead of faces, the researchers say, dogs rely on other signs and signals to form judgments and react. Superficially, this seems at odds with what we know about dogs and how attuned they are to us, but it is more complex than that.

“This reflects differences in how the two species process visual information about others,” Farkas explains. We know that dogs care about human faces. We know that dogs excel at eye contact and recognize their owner from images.

And, despite difference in their brain anatomy, dogs do grasp emotion based on expressions in the human face. That’s the conclusion of Natalia Albuquerque, an animal behaviorist at the University of São Paulo in Brazil. With her team, she exposed 17 adult pet dogs to positive and negative facial images of unfamiliar dogs or humans along with corresponding audio cues. The study, published in 2018, observed a tendency for dogs to lick their lips when confronted with the image of angry human faces. Dog faces or angry human voices alone failed to elicit the response. The results suggest that dogs use visual displays to communicate with humans, but not so much with other dogs.

It isn’t just anger that dogs glean from our faces. In an earlier study, from 2015, cognitive scientists showed that dogs could differentiate between pictures of happy and angry human faces as well.

How Canines Read Strangers

Dogs can even read human expressions in people they do not know. The researchers, including Corsin Müller, PhD, and Ludwig Huber, PhD, from the Messerli Research Institute with colleagues at the Clever Dog Lab at the Vetmeduni Vienna, loaded photos onto touchscreens and showed either happy or angry faces of human strangers to 20 dogs.

Those dogs could recognize human expression in the photos featuring people they had never met, although approaching a happy face remained an easier task. Even though a dog’s spatial resolution is about seven times lower than ours and only a screen was involved, they could still pick up enough detail to recognize emotion, the researchers concluded, due to 30,000 years of domestication and memory of human faces from the past.

A Complex Relationship

“Dogs have a lot of things going for them to make them appealing,” says Ashley Prichard, PhD, a psychologist who studies the overlapping areas of animal cognition, behavior, and neuroscience at the Georgia Institute of Technology. Their large eyes-to-head ratio makes them cute. Plus, they actively seek attention and affection, are trainable for a variety of tasks, and fit in easily with the modern human lifestyle. Of course, these traits didn’t just develop overnight. Humans have domesticated dogs for centuries, including breeding them to fit our preferences. As a result of this interference, Prichard explains, “We have shaped a highly social animal that even befriends other species.” No wonder our dogs are so attuned to our moods.

Even so, there is every reason to be cautious about generalizing dog behaviors based on human perceptions or particular studies, according to Marc Bekoff, PhD, professor emeritus of ecology and evolutionary biology at the University of Colorado, who has written extensively on human–animal interactions. Bekoff says that researchers’ conclusions may shift with the context of the work.

For instance, in any given study, even those that are well-controlled, dogs could be picking up cues from different sensory modalities. It might be that they are getting signals from visual, auditory, and olfactory cues at once. And individual dogs differ. “There is no generalized dog,” he says. In short, while the studies have been done well, there’s still a chance that something has been left out of the equation.

When They Need Us Less, They Filter Us Out More

That cautionary note stands out for dogs mostly living their lives without humans to intervene. Studying these groups is Sindhoor Pangal, a canine behavior consultant in Bengaluru (Bangalore), India, where she has focused on the area’s urban free-ranging street dogs (streeties), studying their response to human facial expressions, body language, and tone. In a teeming metropolis like Bengaluru, with a human population of over 10 million and a stray dog population of 350,000 or so, streeties have to contend with a sea of humanity walking past them. But it turns out that humans, whether expressive or not, fade into the background for these dogs.

Pangal hypothesizes that streeties have a way of filtering out the “irrelevant” humans so their brains don’t fry out from the overstimulation. “When we observe street dogs, we don’t see highly stressed out dogs; we see quite chilled-out dogs,” she says.

This brings us back to the question of context. Because there are so many different studies on the way that dogs and nonhumans in general process human faces, researchers can reach different conclusions given a small subset of data and a narrow set of experimental questions, Prichard says. Plus, there is an important caveat for studies based on eye-tracking and brain scans: They rely on photographs or videos, so we are not seeing how the dog’s brain reacts to the real thing.

As the next step, the researchers will be comparing how dog and human brains process other important visual categories, like body parts, other species, and everyday objects. This will no doubt unlock another piece of the puzzle of how dogs understand and communicate with us.

Making Puppy Eyes

The human-dog relationship has formed over tens of thousands of years of coexistence, and over that time, the two species have changed each other. We can see the changes in dogs more clearly by comparing our modern companions to their relatives, wolves still living in the wild today. The change in dogs was made especially clear by comparative psychologist Juliane Kaminski, PhD, at the UK’s University of Portsmouth and colleagues, who compared dog and wolf facial muscles. The team located distinct muscles present, or more pronounced, in domestic dogs, which allows them to raise their eyebrows and, through this, to convey a more infant-like look that humans find appealing. The eyebrow raise is especially expressed when dogs give their full attention to humans. These facial muscles heighten human-dog communication, the researchers say, by making the white of the eye more visible, a trait somewhat unique in both humans and dogs.

A version of this article appeared in our partner magazine, Inside Your Dog’s Mind, in 2021.

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