Anecdotally, it seems like our furry friends are pretty good at telling when we’re not doing well emotionally. They may be a little cuddlier or less apt to leave our side. A new study adds some science to this observation, showing that sensing stress in humans may even change our pets’ personal behavior and choices.

Researchers at the University of Bristol recently investigated how being exposed to stress from humans could impact dogs’ own thinking and emotions. The study, published in the journal Scientific Reports, involved exposing 18 dogs to the odor of a stressed stranger, a relaxed stranger, and no odor at all, to see how apt they were to approach certain food bowls.

There were two bowls set out initially, a “positive” bowl that had treats, and a “negative” bowl that lacked them. After the dogs learned to approach the positive one, the researchers then put three different bowls out, one near the positive location, one near the negative location, and one in a more neutral spot. Before testing which bowls they’d approach, the team exposed the dogs to the three different odors.

The findings showed that when dogs had been exposed to the stress smell, they were slower to approach the negative area bowl, which was labeled as a pessimistic behavior. The team says the dogs may have learned to reduce risk when they know a person is stressed or that it made them less optimistic that there was any food there. The response could help them conserve energy and avoid disappointment. This suggests an emotional and cognitive impact from the human stress.

While the study helps us learn a bit more about the emotions of our furry friends, it also may have a practical application.

Dr. Nicola Rooney, the study’s lead author and Senior Lecturer in Wildlife and Conservation at Bristol Veterinary School, explains, “Understanding how human stress affects dogs' wellbeing is an important consideration for dogs in kennels and when training companion dogs and dogs for working roles such as assistance dogs.

“Dog owners know how attuned their pets are to their emotions, but here we show that even the odour of a stressed, unfamiliar human affects a dog’s emotional state, perception of rewards, and ability to learn. Working dog handlers often describe stress travelling down the lead, but we’ve also shown it can also travel through the air.”

You can read the whole study here.