Scent of a Human
In the new study, Berns and his team performed fMRI on 12 dogs, including 5 service or therapy dogs and his own dog, Callie, to test their response to biological odors.
The experiment dogs were presented with five scents on gauze pads: a familiar human, an unfamiliar human, a dog that lived in their household, an unfamiliar dog, and their own scent.
The researchers found that the dogs’ caudate nucleus, an area of the brain associated with positive expectations, was most activated by the scent of the familiar person. (Read “How to Build a Dog” in National Geographic magazine.)
This suggests not only that dogs can discern their familiar humans and have a positive expectation about them, but also that these humans’ smells linger in a dog’s mind.
The brain scans showed that the dogs didn’t respond to the other four scents in a meaningful way, though the familiar-dog smell came in second.
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The findings can be used to help train service and therapy dogs, especially those that specialize in anxiety and post-traumatic stress, and make them aware when their owner might need a good cuddle.
Scientists got four dogs — Treo, Fingal, Soot and Winnie — to help them with their first-of-its-kind study, by sniffing samples of bodily fluids from stressed and relaxed people. The dogs were quickly able to correctly inform the researchers which sample was the stressed sample 93.8% of the time.
“We believe this study really developed Treo’s ability to sense a change in emotion at home,” said Helen Parks, Treo’s owner. “The study reinforced for us that dogs are highly sensitive and intuitive animals and there is immense value in using what they do best – sniffing.”
“The research highlights that dogs do not need visual or audio cues to pick up on human stress.” Scientists concluded that the dogs could detect the odor change that is made when humans are stressed.
The furry friends were trained on how to search a scent lineup and alert researchers which sample was the right one. Sweat and breath samples were taken from 36 people before and after they completed a difficult math problem, taken about four minutes apart. Blood pressure and heart rate were also measured before and after the math problem, while participants self-reported their levels of stress.
Can Dogs Smell Fear?
Do you love the way your dog smells? Probably not all of the time, but at least most of the time? Some of the time? Well, if you do, science assures you that you’re not crazy. As articles and forums have begun to pop up talking about that corn chip smell of your dog’s feet, your fascination with your dog’s smell might actually be more scientific than that.
