I can get pretty carried away in my head, projecting a complex panoply of thoughts and emotions onto my chihuahua-dachshund rescue My Girl. Logically, I know that she’s probably just wondering how soon she can get her next meal, walk, and cuddle. But still, that face is so expressive! Surely the side-eye is not simply her looking at me from the side, but a sassy clapback to indicate how peeved she is for being pulled away from a stray french fry on the street? Well, now researchers at the University of Bristol are sharing study results that show at least one strong emotion our pups pick up from us (thus proving it’s not all in my imagination). They say dogs can smell human stress, to the extent that it affects the dogs’ own behavior in response. Great, now I’m stressed about smelling stressed around My Girl!

We’re an ‘emotional contagion’ to our pups?! Our four-legged friends experience “emotional contagion” from the smell of human stress — leading them to make more ‘pessimistic’ choices, say scientists. The University of Bristol-led study is the first to test how human stress odors affect dogs’ learning and emotional states. Previous evidence in humans suggests that the smell of a stressed person subconsciously affects the emotions and choices made by others near them. Bristol Veterinary School researchers wanted to know whether dogs also experience changes in their learning and emotional state in response to human stress or relaxation odours.

Smells like team spirit: The researchers recruited 18 dog-owner partnerships to take part in a series of trials with different human smells present. The participating dogs ranged from eight months to 10-years-od and consisted of two Springer Spaniels; two Cocker Spaniels, two Labrador Retrievers; two Braque d’Auvergne; a Whippet; a Golden Retriever; a Miniature Poodle and seven mixed breed dogs.

A test of bowls: During the trials, the dogs were trained that when a food bowl was placed in one location, it contained a treat, but when placed in another location, it was empty. Once a dog learned the difference between the bowl locations, they were faster to approach the location with a treat than the empty location. The researchers then tested how quickly the dog would approach new, ambiguous bowl locations positioned between the original two. They found that a quick approach reflected ‘optimism’ about food being present in the ambiguous locations — a marker of a positive emotional state — whilst a slow approach indicated ‘pessimism’ and negative emotion.

Stress test: Trials were repeated whilst each dog was exposed to either no odour or the odours of sweat and breath samples from humans in either a stressed — arithmetic test — or relaxed — listening to soundscapes — state. Researchers found that the stress smell made dogs slower to approach the ambiguous bowl location nearest the trained location of the empty bowl, an effect that was not seen with the relaxed smell. The findings, published in the journal Scientific Reports, suggest that the stress smell may have increased the dogs’ expectations that the new location contained no food, similar to the nearby empty bowl location. The researchers suggest that the ‘pessimistic’ response reflects a negative emotional state — and could possibly be a way for the dog to conserve energy and avoid disappointment. The team also found that dogs continued to improve their learning about the presence or absence of food in the two trained bowl locations and that they improved faster when the stress smell was present.

Why it matters: Study lead author Dr Nicola Rooney said: “Understanding how human stress affects dogs’ well-being 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 odours of a stressed, unfamiliar human affects a dog’s emotional state, perception of rewards, and ability to learn.”

[From NY Post]

Maybe I’m stupid (don’t answer that), but it took me a couple read-throughs to wrap my head around the construct of these trials, and I’m still scritchin’ my ears at some parts. Ok, so they trained dogs to know which bowls had treats and which were empty, and then they tested how the dogs reacted to the “ambiguous” bowls in new places. I’m still following along. And they determined that a happy trot to a new bowl indicated optimism while a slow approach pointed towards pessimism, and this is all before human smells enter the picture, yes? Then when they introduced stress-odors, dogs were more cautious, or pessimistic, about the likelihood of finding a treat, than they were when catching whiffs of relaxed odors. Did I pass that reading comprehension test? I’m sorry for approaching the conclusion slowly, it’s just that I recently went from a treat-filled bowl (lunch), to an empty bowl, which is now resulting in a negative emotion. Anyway, I ran all this by My Girl, to which she replied: “All I heard was ‘treat’ and ‘food bowl.’ Cough it up, lady.”

Photos credit: Chewy/Alexander Grey/Unsplash, Duytrg Truong/Pexels