BARI, Italy — Having a bad day? Be careful how you behave around your dog. A new study finds that dogs can read the emotions tied to their owners’ facial expressions, and a bad mood can cause their heart rates to spike.
Researchers from the University of Bari Aldo Moro discovered that our beloved pooches may know us far better than our friends and family. The study shows that while humans wear their emotions on their faces, dogs divulge their feelings about our moods in the directions they turn their heads.
More specifically, if a person appears happy, angry, or frightened, dogs will turn their heads to the left. But if the owner reveals a look of surprise, a dog is more prone to looking to the right.
So how’d they come to these conclusions?
The research team recruited 26 hungry dogs and showed them various photos of a man and a woman while they ate. The photographs, which showed the humans displaying either one of the six basic emotions (anger, disgust, fear, happiness, sadness, and surprise) or a neutral expression, were purposely placed to the sides of the dogs’ line of sight. The canines’ heart rates were also measured during the experiment.
Different expressions proved to lead to consistent reactions among the dogs. For example, the animals typically turned their heads leftward and showed an increase in cardiac activity when they saw faces expressing stronger emotional gestures like anger, fear, and happiness. Additionally, they took much longer to return to eating their meals after exposure to these particular emotions.
The authors believe these reactions indicated the dogs were feeling more stressed by these photos. A look of surprise, however, led to a head-turn to the right because the dogs didn’t find the expression to be as stressful or threatening to them. In either case, if a dog turned its head one way, it would indicate the opposite hemisphere of the brain was activated.
“Clearly arousing, negative emotions seem to be processed by the right hemisphere of a dog’s brain, and more positive emotions by the left side,” says Marcello Siniscalchi, one of the co-authors, in a statement.
Siniscalchi, along with authors Serenella d’Ingeo and Angelo Quaranta say that the study’s results confirm other research that show dogs use different parts of the brain to process human emotions, and that the right side of the brain plays a key role in the “fight or flight” reaction in mammals. Prior work has also shown that man’s best friend has similar responses to human odors and changes of pitch when speaking.
The full study was published June 19, 2018 in the journal Learning & Behavior.