What causes a dog to slink away from a cranky person, when they will quietly approach and lean against someone who is weeping? We've all seen it - they can respond to our feelings. And science agrees dogs have emotions too.
Author
- Mia Cobb
Research Fellow, Animal Welfare Science Centre, The University of Melbourne
These social skills could underpin dogs' success in living with us. But do you think your dog could tell an angry person's face from a sad or fearful one?
New research published in the journal iScience explored that question, and revealed interesting findings from magnetic resonance imaging (MRI) scans of dogs' brains.
Scanning dogs' brains
Dogs are sensitive to human faces . They look longer in response to our emotional expressions and sounds compared with neutral ones.
Scientists weren't sure whether dogs were just differentiating "good mood" (happy) from "bad mood" (angry, fearful or sad), or treating these expressions as genuine indicators of different emotions.
The new study, by Raúl Hernández-Pérez, a neuroscientist at the University of Vienna, and colleagues, explored this gap using MRI to scan pet dogs' brains while they were viewing photos of human faces.
Building on their earlier work , the researchers found evidence that dogs do process images of our distinct emotional expressions differently.
The researchers used machine learning and showed that when looking at a dog's whole brain, a different brain region was activated to distinguish between fear and sadness (the right rostral suprasylvian gyrus, to be precise), than between fear and anger (this was in the right mid ectosylvian gyrus and left splenial gyrus).
The analysis didn't detect a difference in the brain areas activated when dogs were shown images of human anger and sadness. Fear stood out from the other negative emotions.
This raises the question: why?
It might be that fear and anger are simply more attention-grabbing than sadness.
Other research has found dogs react to fear and anger faster, and with a bigger physical response, such as a raised heart rate. This is likely because they're the expressions most likely to call for a quick response from dogs to stay safe.
Sadness is less likely to pose a direct threat to dogs living with people, so they experience less urgency to respond to it. We know some dogs don't respond with the heroic Lassie behaviour we might like when we are in distress.
Although the numbers in this new research were small (eight and twelve dogs across the two parts of the study), this is the first MRI-based proof-of-concept evidence that dog brains can distinguish between two human facial expressions of distinct negative emotions. It indicates dogs' neural representation of our emotion goes beyond a simple valence (good/bad) split.
This shows us that perceiving emotion in others (even across species) isn't handled by one single "emotion centre" in the brain - in dogs, in humans, or in other animal species. It's spread across a network of regions working together as part of living socially.
A sense-ational result
The authors of this study point out that using still images of humans is a very people-centred way to explore how dogs interpret our emotional states.
We know dogs live in rich sensory worlds where the scent and sound of our speech also convey emotions, shaping how dogs respond to us.
In fact, even wolves who have grown up around people show the same kind of response to the odour of human fear as dogs. This highlights the important role of learning, as distinct from evolutionary differences in canid bodies or how they respond to people. Dogs (and wolves) are learning about us in every interaction we have with them.
Dogs are adept at watching, smelling, and listening to our emotions, learning how these signals predict our behaviours toward them, and using this information to live with people harmoniously.
Returning the favour, learning more about how dogs express their emotions seems like the least we can do.
Mia Cobb receives funding from The Chaser Initiative and the University of Melbourne.
