Whether it's a tricky math problem or an unexpected bill, daily life is full of stressful experiences. Previous studies have suggested dogs might pick up on human emotions, possibly through smell, but questions remained over whether they could detect stress and if this could be done through odor(气味).
Clara Wilson is a PhD student at Queen's University Belfast and first author of a new research. He and colleagues report how they first constructed a stand bearing three containers, each lid with a hole. They were able to train four dogs to indicate the container holding a particular breath and sweat sample, even when the line-up included unused gauze(纱布), samples from another person, or samples from the same person taken at a different time of day. Then the team turned to breath and sweat samples collected from 36 people asked to count backwards from 9, 000 in units of 17. The participants reported feeling stressed by the task and, for the 27 who carried it out in the laboratory, their blood pressure and heart rate rose.
The dogs were taught to pick out samples taken just after the task from a line-up that included two containers holding unused gauze. The researchers then tested whether the dogs could do the same when the line-up included unused gauze and samples taken from the same participant just before the task, when they were more relaxed. Each set of samples was shown to a single dog in 20 trials. The results reveal that the dogs chose the"stressed"sample in 675 out of the 720 trials.
"While it is unclear what chemicals the dogs were picking up on, the study has definitively proven that people, when they have a stress response, their odor profile changes, "said Wilson, adding the findings could prove useful when training service dogs, such as those that support people with post-traumatic stress disorder (创伤后应激障碍).
