It is a characteristic of our faithful four-legged friend that strangely knows when we are in a bad mood. Dog owners have long been convinced of this.
However, scientists have now shown that dogs are indeed influenced by the emotions of their owners.
Researchers from the University of Bristol found that dogs’ behaviour changes due to the smell of stress in our sweat and breath.
Dogs that smelled a stressed human also had a more “pessimistic” outlook on life.
Lead researcher Dr Nicola Rooney said: ‘Working dog handlers often describe how stressful it is to carry the lead, but we have shown that this can also happen through the air.’
Researchers have found that dogs become more pessimistic when they smell stressed people. In a test, 18 dogs (pictured) were found to make less optimistic choices after smelling the scent of stress
Previous research into dogs’ emotions has shown that they are particularly sensitive to the moods and actions of the people around them.
However, it was not yet clear whether scent played a role in the spread of these emotional states.
Dr Rooney said: ‘Dog owners know how sensitive their pets are to their emotions, but here we show that even the scent of a stressed, unfamiliar person can affect a dog’s emotional state, its perception of rewards and its ability to learn.’
To test this theory, the researchers recruited 18 human-dog pairs to participate in a series of experiments.
First, the dogs were trained to recognize the difference between a good and a bad situation.
Dogs were trained to know that bowls in some locations contained treats and in others none at all. To measure the dog’s optimism, a bowl was placed in a new location while the researchers measured how quickly the dog walked toward it.
When a food bowl was placed in one location, there was a treat in it, but when an identical bowl was placed in a different location, it was empty.
Once the dogs learned the difference between these locations, they were able to walk to the location with the treat faster than to the empty location.
When a third box was placed in a new location, the researchers measured how long it took the dog to approach it to investigate.
If the dog walked quickly, it was a sign that he was optimistic and that there would be a reward in the bowl.
Conversely, the less the dog was inclined to check the new bowl for food, the more pessimistic his attitude.
Dogs’ ability to detect human stress may have evolved to help them conserve energy and avoid disappointment, researchers say (stock image)
During the trial, the dogs underwent the same test while being exposed to the scent of sweat and breath samples from people who were not their owners.
These odors were collected while the human participants were relaxing by listening to soundscapes or while stressed by a math test.
The researchers found that dogs exposed to stress odors were significantly less likely to approach the food bowl to check, regardless of its location.
However, when exposed to the scent of a relaxed human, the dogs went to the food bowls more often than when exposed to a neutral-smelling cloth.
Later tests also showed that the dogs became increasingly better at recognizing the locations of the bins and learned the difference more quickly when exposed to a stress odor.
Researchers found that dogs were less likely to go to a litter box in a new location if they could smell a stressed human. But if they could smell a calm human, the dogs were more positive and more likely to check out a new litter box.
Lead author Dr Zoe Parr-Cortes told MailOnline: ‘Dogs are one of our best friends and have evolved alongside humans for thousands of years.’
This causes dogs to experience a phenomenon called “emotional contagion,” where they take on the moods of their owners.
“This can be useful because a threat perceived by another group member may also be a threat to themselves. Therefore, detecting and responding to fear or ‘alarm’ in others can be useful in avoiding a common threat,” Dr. Parr-Cortes explains.
Dogs may have evolved this “pessimistic response” to human stress to conserve energy and avoid disappointment.
According to the researchers, this discovery could help professional dog owners and handlers understand how their own emotions influence their dog’s training.
This can be an important consideration for working dogs in stressful roles such as police work or search and rescue operations.
As dogs have evolved alongside humans, they have developed several incredible skills to communicate with and understand what their human partners are doing, including detecting our emotions
However, social contagion can be just as important for the average owner training a puppy.
Dr. Parr-Cortes adds: ‘It (human stress) may make them less likely to try something risky if they’re afraid they’re going to be disappointed.
‘A relaxing scent does not have this effect. Staying calm or doing a relaxing activity before training your dog can reduce this effect.’
Although previous research has shown that dogs respond in certain ways to other human emotions, no research has yet examined how these emotions influence optimism and pessimism.
In the future, researchers would like to look at the effect of emotions such as happiness or deep relaxation on the mood of dogs.
This research was published in Scientific reports.