Research indicates that the closeness between humans and dogs is remarkable, as animals are capable of discerning and reacting to human facial expressions, identifying both positive and negative feelings.
A recent study demonstrated that this capacity for understanding is more sophisticated than previously thought. It was found that dogs can differentiate various human emotions, perceiving whether a person is feeling anger, fear, sadness, or happiness.
The results of this investigation were published in August in the scientific journal iScience. The methodology employed aimed to analyze the brain activity of dogs while they were exposed to various human expressions, a process that required considerable logistical complexity from the research team.
Initially, eight dogs—six Border Collies, one Labrador, and one Golden Retriever—were trained to voluntarily and unrestrainedly remain in magnetic resonance imaging machines, staying still during the tests.
In the initial phase of the research, the animals were inside the machine observing images of individuals with neutral or happy expressions. When exposed to happy faces, an increase in brain activity was observed in areas related to cognitive processing and reward.
Subsequently, in another experiment, researchers presented photographs of a single person, but each photo represented a distinct emotion: fear, anger, sadness, and happiness. To ensure that the differentiation was based solely on facial expression, the person used was unknown to the dogs, thus eliminating the influence of familiarity with their owners or other cues such as tone of voice and body language.
Magnetic resonance imaging allowed for the recording of the dogs' brain activity in response to each image, confirming that they showed distinct responses to negative emotions (anger, fear, and sadness) and positive ones (happiness).
Additionally, the study investigated whether the animals could distinguish the nuances between negative emotions. The answer was affirmative: the dogs could differentiate fear from anger and fear from sadness. However, no distinction was made between anger and sadness.
This means that dogs are capable of identifying emotions linked to facial expressions and recognizing specific categories beyond mere classification as 'positive' or 'negative'. It is important to note, however, that these findings do not imply that dogs possess the same emotional understanding as humans, given that they are different species. Furthermore, the study did not assess the canine ability to differentiate human positive emotions nor did it include stray dogs with little human interaction.