Is this the secret to dogs’ empathy? Dogs can sense stress in a person’s sweat or breath through their sense of smell, a study has found.
Researchers from Queens University, UK, asked 36 participants to solve a difficult math problem and collected sweat and breath samples before and following they solved the problem. Participants answered a questionnaire regarding their level of stress before and following performing the task, and the researchers used only samples from participants whose blood pressure and heart rate increased following solving the problem.
The researchers also trained dogs to ‘scent line-up’ so that researchers might pick out samples they wanted.
Smell extraction is an investigation technique in which a police dog smells evidence found at a crime scene, then arranges samples taken from several people, including a suspect, to find a sample that matches the smell with the evidence.
It is similar to a scene in a crime movie in which a criminal is pointed out from among the suspects lined up behind a special glass window that witnesses cannot see from the inside. What humans see with their eyes, dogs see with smell.
The researchers showed the dogs samples from each participant when they were stressed and when they were calm. As a result, the dogs correctly picked a ‘stress sample’ for each test. The time interval between taking the two samples was only 4 minutes.
This means that when a person is stressed, sweat and breath emit a different odor, which dogs can detect. The dog was able to tell whether it was stressed or not, even by the smell of a stranger. This means that dogs can empathize with people through their sense of smell.
Dog owners who participated in the study also responded that “during the experiment, the dog’s ability to detect changes in household emotions seemed to increase.”
The researchers expected that these results might be used for training dogs that help with psychotherapy or emotional support.
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“This study shows that dogs can tell if people are under stress just by smell, without relying on sight or sound,” said Clara Wilson, from the Department of Psychology at Queens University, who led the study. “It will contribute to a better understanding of how we interpret and interact with people’s psychological states.”
This study was published in the academic journal ‘PLOS One’.
