A pile of recent studies show how canines pick up chemical and physiological cues from people that allow our moods to become “contagious.”
BYSTACEY COLINO,PUBLISHED OCTOBER 1, 2021
Dog-owners often feel that their pooches are good at picking up on their emotions. This isn’t a figment of their imaginations. New studies show how behavioral and chemical cues from humans can affect dogs in ways that enable them to not only discriminate between their owners’ fear, excitement, or anger, but also to “catch” these feelings from their human companions.
Just as human toddlers look to their parents for cues about how to react to the people and world around them, dogs often look to humans for similar signs. When their people project feelings of calm and confidence, dogs tend to view their surroundings as safe and secure.
“The emotional connection between humans and dogs is the essence of the relationship,” says Clive Wynne, a professor of psychology and director of the Canine Science Collaboratory at Arizona State University. “Dogs are amazingly social beings, so they are easily infected with our warmth and joy.” But the converse is true as well, which means their owner’s stress and anxiety can also become the dog’s stress and anxiety.
This interspecies emotional contagion, as psychologists call it, has a psychological, a physiological, and a behavioral basis. In the last few years, multiple studies have shown that the transmission of emotions depends on the release of certain hormones (such as oxytocin), body odor changes in humans, the firing of key neurons in the pooches and their people, and other physiological factors.
Recent research also shows that the extent to which people and their pups catch their owner’s emotions depends on the duration of their relationship. That’s an especially noteworthy phenomenon right now, as people and their canine companions continue to spend more time together during the pandemic.
A primitive form of empathy
There is a spectrum of emotional connection between people and their dogs, ranging from being able to detect and understand each other’s feelings to actually sharing the same emotions.
Studies have shown that dogs can catch our yawns, experience an increase in cortisol levels when they hear a baby crying—just as humans do—and respond to the emotional tone of our voices. While interacting with each other or even just looking into each other’s eyes, research has found that people and their dogs experience the release of oxytocin, often called the “love hormone” or the “cuddle hormone”—though the hormone’s effects are more complicated than that, given that it can foster trust and generosity in some situations and envy in others.
When it comes to bonding, “oxytocin release is stimulated by eye contact or social touch such as petting, and it works both ways—from dog to human and from human to dog; it’s like a feedback loop,” explains Larry Young, a professor of psychiatry and director of the Silvio O. Conte Center for Oxytocin and Social Cognition at Emory University. “In order to have emotional contagion, dogs need to be able to recognize the emotions of their owner—that requires attention, which oxytocin facilitates. It causes the brain to focus on social cues.”
Dogs also have “affective empathy”—which is defined as the ability to understand someone else’s feelings—toward people who are important to them. Emotional contagion is a primitive form of affective empathy that reflects the ability to actually share those feelings. For example, in a 2020 study published in the Canadian Journal of Experimental Psychology, researchers examined how dogs reacted when their owner or a stranger in their home pretended to laugh or cry. The dog bestowed more attention on the person who appeared to be crying, both through visual or physical contact. And, when the stranger cried, the dogs showed higher stress responses, explains study co-author Julia Meyers-Manor, an associate professor of psychology at Ripon College in Ripon, Wisconsin.
“All of empathy has some component of contagious emotions,” explains Meyers-Manor. “In some ways, recognizing another [creature’s] emotion is more complex cognitively speaking, whereas feeling what another animal feels is simpler.”
When someone ends up sharing another person’s feelings, it’s often because during conversation humans naturally tend to mimic their companion’s facial expressions, posture, and body language, without being consciously aware of it. The incremental muscle movements that are involved in this phenomenon trigger the actual feeling in the brain by causing mirror neurons—brain cells that react both when a particular action, like smiling, is performed and when it is observed—to fire, conjuring up the emotion as if you were experiencing it naturally. It turns out that this rapid mimicry also occurs in dogs when they interact or play with each other, and it may be activated when pooches interact with people, too.
After all, when dogs and humans are angry, Meyers-Manor points out, their facial muscles are often tightened, their teeth may be clenched, and their body tenses up. This means that when you’re in the presence of an angry dog or when you’re enraged, each of you may unconsciously mirror the other’s facial expressions or body language and end up feeling the same way. “Because of our close connection with dogs, we have co-evolved to detect each other’s [emotional] signals in ways that are different from other species,” Meyers-Manor says.
For many years, researchers assumed that when dogs became domesticated, the possibility of emotional contagion served as a survival mechanism—if dogs were able to read and share their owner’s emotions, they would be better cared for. More recently, that thinking has shifted. A recent study in Scientific Reportsfound that it’s the bond and life experiences between dogs and their owners that account for the release of oxytocin during interactions. Also, a study in a 2019 issue of Frontiers in Psychologyfound that the extent to which emotional contagion occurs between humans and their canine companions increases along with the time spent sharing the same environment.
Facial expressions and body odor
Sensory factors also can influence emotional contagion between people and their canine companions. For one thing, dogs have a remarkable ability to read the facial expressions and body cues of human beings, experts say. While some research has found that dogs focus more on bodily expressions of emotion than on facial cues in both humans and other dogs, other studies have shown that dogs process human facial expressions similarly to the way people do. A study in a 2018 issue of the journal Learning & Behavior found that dogs respond to human faces that express six basic emotions— anger, fear, happiness, sadness, surprise, and disgust—with changes in their gaze and heart rate.
“We know that dogs and humans synchronize their behavior—dogs often match the natural movements of their owners—so the fact that they synchronize their emotions isn’t surprising,” says Monique Udell, an animal behaviorist and associate professor of animal sciences at Oregon State University in Corvallis. “Dogs are watching us very closely—some of this is based on our gaze and body language but also on the sounds we make and the scents we give off.”
On the auditory front, research has found that when dogs hear expressions of distress, like crying, or positive sounds like laughing, they respond differently than they do to other vocalizations or non-human sounds. When they’re exposed to these human sounds, dogs are more likely to look at or approach their owner or the source of the sound.
When it comes to olfaction, “dogs are very sensitive to body odor—it’s how they can detect diabetes and possibly epilepsy [in people],” Wynne says. In a study in a 2018 issue of Animal Cognition, researchers set up an experiment in which Labradors and Golden Retrievers were exposed to samples of three human body odors—representing fear, happiness, and a neutral emotion: The researchers induced these particular emotions in the male participants then took odor samples from their armpits. These odors were then aerosolized through a special dispenser in a space where the dogs could move freely in the presence of their owners or strangers: When the dogs were exposed to the scent of fear, they exhibited more stressful behaviors and higher heart rates than they did in the presence of “happy” odors; the dogs were also more interested in the strangers when the happy odors were present.
When they pick up on human emotions, “a lot of times dogs use composite signals, which includes information coming in from a cocktail of their senses, including sight, hearing, olfaction, and maybe through touch if someone is nervous,” says Marc Bekoff, professor emeritus of ecology and evolutionary biology at the University of Colorado, Boulder, and author of A Dog’s World: Imagining the Lives of Dogs in a World Without Humans. “
But it’s important to remember, he adds, that not all dogs are exactly alike, psychologically, physiologically, or socially. “Dogs are individuals, and you need to know who they are,” Bekoff says. “I always tell people: You’ve got to be fluent in dog.” Bekoff says that dog-owners should tune in to what their dogs are trying to tell them with their barking, other vocalizations, facial and body language.
A bidirectional effect?
In general, the range of emotions that dogs experience is probably more limited than what most humans experience. “I don’t think dogs’ emotions are very complex,” says Wynne. “They experience primal emotions including warms ones like happiness and excitement, and cold ones like fear and anxiety.” Beyond that, there are many unknowns, and one of the challenges with doing this kind of research is that dogs can’t say exactly how they’re feeling at any given moment.
It also isn’t clear whether humans can catch emotions from their dogs because studies haven’t looked at this question, though some experts believe it’s highly possible. “I certainly feel that my dog’s happiness can lift my mood,” says Wynne, author of Dog Is Love: Why and How Your Dog Loves You. Bekoff agrees: “I do think we pick up their emotions, too. Sometimes it’s easier to pick up their fear and stress. However, happy dogs are also easy to read if they run up to you with their tails wagging and their ears are forward, not tucked back.”
Whether they’re dog owners or not, people are highly adept at identifying both positive and negative emotions in dogs’ facial expressions, partly because shifts in facial expressions that express specific emotional states are shared across both species, research has found.
One instance that suggests stress and tension can be contagious in both directions involves leash reactivity: If your dog barks, growls, or lunges at other dogs, people, or cars while you’re walking him or her on a leash, you might feel embarrassed or stressed out, which can cause you to tense up and exacerbate your dog’s fear and anxiety. This in turn “can be a trigger for the dog doing it again,” Udell says, which can lead to an unfortunate cycle.
Still, sharing each other’s emotional ups and downs tends to be mostly beneficial because it helps us connect on a deeper level, and it has survival value, too. “If you think back to our ancestors, it was a life-or-death proposition that your dog could alert you to something so you could act quickly,” Wynne says. “The two-way street on the alarm side is mutually advantageous for both [species].”
Sharing a home, a life, a family, and activities contribute to the quality of the human-canine connection. Sharing each other’s feelings “helps us understand each other better, and it facilitates the bond that develops and how it’s maintained over time,” says Bekoff. “When dogs and humans share emotions, it’s like social glue.” It acts like a strong adhesive that binds us together—often for life.