CLARA WILSON FROM BIG THINK
When we’re stressed, our hormones and nervous system produce all sorts of odors, which dogs can pick up on.
Dogs have a long history alongside humans, giving them an amazing ability to read human cues. Dogs also possess an incredible sense of smell, which enables them to detect diseases, such as COVID and lung cancer, in humans from odor alone. Whether dogs’ capabilities extend to detecting odours associated with psychological states has been explored far less.
When people are stressed, there are hormonal and nervous system changes that alter the kinds of odors produced by the body. My colleagues and I wanted to know if dogs can discriminate between odor samples taken from the same person before and after becoming stressed. To do this, we took ideas from the field of biomedical detection dogs (sniffer dogs in a laboratory setting) and combined these ideas with techniques used to test dogs’ perceptions of odours.
Our results are published in the journal PLOS One.
To test whether dogs could detect an odor associated with psychological stress, we attached sensors to the study participants to continuously measure their heart rate and blood pressure. Participants also rated how stressed they were feeling before and after taking part in the task.
Before the task started, participants wiped gauze on the back of their neck, placed it into a sterile glass vial, and exhaled into the vial. We then got the participants to perform a rapid mental arithmetic task to induce stress in them.
After the task, participants provided another rating of their stress and two additional sweat/breath samples.
The total time between the collection of the relaxed (pre-task) and stressed (post-task) samples was four minutes, reducing the likelihood that the participants experienced changes other than the onset of stress.
We only included samples in the study if the person reported finding the task stressful, and both their heart rate and blood pressure had increased during the task. We presented samples from 36 people to the dogs.
