New research from the University of Bristol shows that dogs pick up on human stress smells, making them more pessimistic about their choices. Published in Scientific Reports, this study is the first to examine how human stress odors affect dogs’ learning and emotions.
Researchers found that, like humans, dogs’ emotions and decisions change based on whether they smell stress or relaxation. The study used tests to measure if dogs made more optimistic or pessimistic choices based on these smells.
Researchers tested 18 dog-owner pairs with different human smells to see how they affected dogs’ behavior. Dogs learned to find a treat in one bowl location rather than another. When faced with new bowl locations between the original ones, a quick approach showed optimism, while a slow approach showed pessimism.
The study found that dogs exposed to the smell of human stress were slower to approach the new bowl location nearest to the empty bowl, unlike those exposed to relaxed smells. This suggests that stress odors made dogs expect no food in the new location.
Researchers found that dogs’ ‘pessimistic’ response to stress smells might be a way to avoid disappointment and save energy. Dogs learn about food presence faster when exposed to stress odors.
Dr. Nicola Rooney from Bristol Veterinary School said understanding how human stress impacts dogs is crucial for their wellbeing, especially in kennels, training, and working roles.
The study shows that even the scent of a stressed stranger affects a dog’s emotions, reward perception, and learning ability.
Journal reference:
- Parr-Cortes, Z., Müller, C.T., Talas, L. et al. The odour of an unfamiliar stressed or relaxed person affects dogs’ responses to a cognitive bias test. Scientific Reports. DOI: 10.1038/s41598-024-66147-1.