Dogs perceive the world through their sense of smell—and this includes the way they gauge their human's emotions. Just like us humans can tell a person is stressed by seeing their facial expressions and body language, pups can determine it by the levels of cortisol, known as the “stress hormone,” you exude. Interestingly, a study has found that they have a more pessimistic outlook if they can tell you're feeling stressed.
Scientists had long been aware that dogs can detect if humans are stressed. However, a team of researchers from the University of Bristol, Cardiff University, and the British charity Medical Detection Dogs set out to find out if this information had an effect on them, particularly on their emotions and how they behave. To find this out, the team recruited 18 dogs of different breeds, and a group of human volunteers—who the pups didn't know. They were put under a lot of stress in the name of dog science.
First, the humans had their cortisol levels raised by making them give a speech on the spot and take a math test as the researchers kept a serious face to enhance the tension. Once done, they got to unwind by laying on a beanbag chair and watching calming footage of forest and sea landscapes. Throughout the process, the scientists gathered samples of their sweat, both in tense and relaxed moods, using pieces of cloth stuck to their armpits.
Meanwhile, the dogs were being trained on where to find treats. Bowls on one side of the study room always contained food, while bowls on the opposite end never contained food. As they learned this, they approached the ones with food quickly and moved slowly towards the empty ones. These markedly different responses cemented a way to log behaviors based on the dogs’ expected results.
Once the dogs were successfully taught that bowls in a certain location had food (which they clearly had a more positive and excited response to) and bowls on the opposite end definitely didn’t have food (which was met with more disappointment), the researchers removed the original bowls and introduced a third one in a neutral, ambiguous scenario. “Do they approach quickly, optimistic that there's going to be a food reward in there, or do they approach more slowly, with a more pessimistic outlook that there might not be food in that bowl?” lead study author Dr. Zoe Parr-Cortes told NPR.
The sweaty pieces of cloth were then brought out for the dogs to sniff before presenting them with the mystery bowl. The team observed that when the pups smelled stress, they were more hesitant to take a look at the bowl, as if they weren't expecting to find a treat there. On the other hand, the “calm smell” didn't seem to affect their behavior. “It basically shows that the stress smell might affect how [dogs] respond to ambiguous situations,” Parr-Cortes added. “They might be less likely to try something risky if they think they’re going to be disappointed.”
Ultimately, this means that things that make us feel stressed are stressful for dogs too, whether you realize it or not. “If you're stressed, you're probably more likely to be tense and not as patient,” Parr-Cortes said. “[And it] might literally make them have different behaviors.”
So, even if you love your dog unconditionally, you may inadvertently be making things tough for them. Instead, try your best to keep calm and take a break. If you're having a bad time, you can always count on your pet to be there for you, so it’s important to be there for them too.
Sources: Dogs can discriminate between human baseline and psychological stress condition odours; A study finds that dogs can smell your stress — and make decisions accordingly
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