Do you sometimes think that your dog knows what you are feeling? Now, two different studies have proven that man’s best friend is able to recognize human emotions by looking at faces.

Researchers at the University of Mexico trained seven domestic dogs to remain still in an MRI scanner that produces detailed images inside the body. Each dog was shown 50 photos of different people and 50 images of inanimate objects to see how its brain reacted.

Brain activity greatly increased when the canines saw human faces. This indicates, the study said, that dogs recognize human emotions through facial cues. "The recognition of human faces by dogs could be an essential factor for establishing attachment with humans," the study added.

Matching facial and audio cues

Another project, by a team of animal behaviorists and psychologists in Brazil and England, also showed that dogs identify people’s emotions by looking at their faces. Seventeen domestic dogs were shown a pair of photos of someone looking happy or sad, along with recordings of a person’s voice, speaking in a cheerful or angry tone.

“We wanted to see if the dogs could assess the emotional content of the human voices,” explained Natalia De Souza Albuquerque, a researcher at the University of Sao Paulo in Brazil.

The researchers discovered the dogs spent more time looking at the facial expression that matched the tone of voice.

“When dogs were hearing positive sounds they would look longer to positive faces,” said De Souza Albuquerque. "And when they were listening to negative sounds they would look longer to negative, angry faces.”

According to the researchers, this means that dogs are able to integrate two sources of sensory information to perceive emotion in people in general, not just their owners. This may be an inherent ability in canines, which some scientists believe were domesticated at least 30,000 years ago.

How dogs react to human emotions

Next, the research team wants to conduct more experiments to learn how dogs react to different human emotions. Do they react the same way we do to one another?

“We can see whether dogs can use a human-like principle or human-like strategy to perceive, understand and respond to human emotion,” said Kun Guo, with the University of Lincoln’s school of psychology in England.

But many people who have bonded with their dog already know they are feeling and reacting to emotions from each other.