Dog owners often believe their pets can sense when they’re having a bad day. Scientists now offer an explanation based on new research. A study published on August 10 in the journal iScience demonstrates that dogs’ brains respond differently to various human facial expressions such as happiness, anger, fear, and sadness.
Insights from Brain Scans
Researchers used brain scans to observe pet dogs viewing photos of people showing different emotions. The study shows dogs’ brains react differently depending on the expression, indicating they do more than categorizing a face as positive or negative.
Earlier studies indicated dogs could differentiate happy faces from negative ones. However, it remained unclear if they could distinguish between different negative emotions. The new findings suggest they process some of these emotions differently, especially fear compared to anger and sadness.
“Humans are really good at picking up small details on the face, and so are dogs,” said Raúl Hernández-Pérez from the University of Vienna.
Dogs’ Reaction to Emotional Expressions
Researchers first showed eight dogs photographs of unfamiliar people with happy or neutral expressions, and scanned their brains. Happy faces activated areas linked to cognitive processing and rewards. Specifically, increased activity was noted in the temporal cortex and caudate nucleus.
The surprise was the caudate nucleus, associated with rewards like food and praise, responding to happy faces. This suggests that even a happy face from an unfamiliar person might carry positive associations for dogs.
The experiment expanded to include happiness, anger, fear, and sadness. Analysis using machine-learning techniques identified distinct patterns linked to these expressions. Dogs’ responses to happy faces differed clearly from those to negative expressions, but fearful faces produced a unique pattern compared to angry or sad faces.
The lack of clear distinction between anger and sadness in dogs implies a different understanding of emotions than humans.
Role of Experience and Evolution
Dogs’ attunement to human behavior may explain why they often sense distress in their owners. Having evolved alongside humans over thousands of years, dogs developed social skills crucial for interpreting human signals.
Even though the study involved 12 pet dogs familiar with humans, results may differ for street or free-ranging dogs. More research is needed to explore canines’ interpretation of human emotions in various scenarios.
Owners’ observations over the years align with these findings; dogs are indeed sensitive to human emotions. While they may not grasp sadness or happiness as humans do, their brains are evidently attuned to emotional signals displayed on human faces.
“Emotions are a powerful channel of communication,” Cuaya noted, emphasizing the bidirectional nature of emotional communication.