Image of one of the dogs that participated in the study during functional magnetic resonance imaging scans to measure their brain activity while viewing images of human faces with different expressions. Credit: Laura V. Cuaya/University of Vienna.
Science Desk, August 10 (EFE) – Dogs, at least domestic ones, are very good at recognizing human facial expressions, especially joy, although they can also distinguish between negative ones, such as fear or sadness, according to evidence from new research that has studied the biology behind this ability.
Researchers led by the University of Vienna published in iScience the results of two experiments on a group of domestic dogs in which they underwent a series of scans while viewing images of human faces.
The results provided, for the first time, evidence that dogs can distinguish between negative facial expressions, such as anger, sadness, and fear.
The ability of dogs to pick up on small details in the face makes them “very interesting,” because by studying their brains we can understand what adaptations they have developed to support their remarkable social and emotional understanding of humans,” said lead author Raúl Hernández-Pérez of the University of Vienna, quoted in the publication.
The researchers first focused on happiness, an expression that, according to previous studies, is of particular importance to dogs.
While undergoing brain scans, the animals viewed images of unfamiliar people with happy or neutral expressions. Happy faces activated the temporal cortex and the caudate nucleus, brain regions associated with higher cognitive processing and reward processing, respectively.
This suggests that happy human faces “may have emotional significance for dogs,” explained another of the authors, Laura Cuaya, also of the University of Vienna.
To see if these same brain regions responded to other emotions, the same procedure was performed with images of happy, angry, fearful, and sad faces, and the brain activity was analyzed using machine learning.
The result was that the dogs They did not react in the same way to these negative emotions.
The network formed by the temporal cortex and the caudate nucleus responded exclusively to happiness, allowing researchers to easily distinguish brain reactions and understand that the canine brain does not simply classify the world as good and bad.
A whole-brain analysis revealed distinct activity patterns that differentiated fear from anger and sadness, providing the first evidence that dogs can distinguish between specific negative facial expressions.
This ability doesn’t mean dogs experience emotions exactly like humans. Furthermore, a photograph of a face doesn’t tell the whole story; in real life, dogs observe body language, listen to the nuances of our voices, and detect information through our scent, the team noted.
The animals that participated in the study were pets from loving families, but dogs living on the streets move in a very different social world and may process human signals differently.
The team now wants to take a more dog-centric approach to understand how dogs integrate brain signals to interpret the humans around them. They also plan to compare how human and canine brains process the same emotional signals.
