Previous studies have shown that dogs can differentiate between human emotions from signs such as facial expressions. But this is not the same as emotional recognition, according to Dr Kun Guo, from the University of Lincoln's School of Psychology.
"This is the first empirical experiment that will show dogs can integrate visual and oratory inputs to understand or differentiate human emotion as dog emotion," Kun told Reuters.
Experiments were carried out by a team of animal behavior experts and psychologists at the University of Lincoln, UK, and University of Sao Paulo, Brazil.
They presented 17 untrained domestic dogs with images and sounds conveying either positive or negative emotional expressions in humans and dogs.
Related: Meet Tillie, a hero dog honored in Washington:
NTP: Hero dog in Washington
Dogs can read human emotions
Discover More Like This
BACK TO SLIDE
The dogs used in the testing were unfamiliar with the procedure; avoiding any chance of conditioning. The vocalization sound accompanying the human faces was also unfamiliar.
"We used Portuguese to British dogs so they weren't habituated with any words, they weren't familiar with any words. So, we wanted to see if the dogs could assess the emotional content of the human voices and whether they would actually discriminate the emotional information within them," explained Natalia De Souza Albuquerque, a PhD student in experimental psychology.
The results, published recently in the Royal Society journal Biology Letters, found that dogs spent significantly longer looking at the facial expressions which matched the emotional state of the vocalization, for both human and canine subjects.
"What we found is that when dogs were hearing positive sounds they would look longer to positive faces, both human and dog. And when they were listening to negative sounds they would look longer to negative, angry faces," added De Souza Albuquerque.
The study shows that dogs can integrate two different sources of sensory information into a perception of emotion in both humans and dogs. This means dogs must have a system of internal categorization of emotional states. Among animal groups, it's a cognitive ability previously only evidenced in primates.
The researchers believe that the ability to combine emotional cues may be inherent to dogs. As a highly social species, detecting emotions in humans would have helped them in their domestication by people over the generations.
Dr Kun Guo now wants to conduct more experiments in a bid to better understand how man's canine companions decipher human emotions. "(So) we can see whether dogs can use a human-like principle or human-like strategy to perceive, understand and respond to human emotion," he said.
"If we can understand this, surely we can understand dogs better."
Want more pups? Check out these dogs having the time of their lives in the snow:
Dogs In Snow
Dogs can read human emotions
NOTTINGHAM, UNITED KINGDOM - JANUARY 21: Freddy the Boston Terrier plays in the snow on January 21, 2013 in Nottingham, United Kingdom. The United Kingdom has suffered a weekend of heavy snowfall with many transport routes affected. (Photo by Laurence Griffiths/Getty Images)
A German Shepherd puppy experiences snow for the first time during a snowfall January 21, 2014 in Manassas, Virginia. The Washington, DC area and much of the Northeast is under a winter storm warning for Tuesday, with the National Weather Service forecasting 6 to 11 inches of snow by the end of the day. The snow will also come with bitter cold, and the area is also under a wind chill advisory for Tuesday into Wednesday. AFP PHOTO / Karen BLEIER (Photo credit should read KAREN BLEIER/AFP/Getty Images)
WASHINGTON, DC - JANUARY 22: English foxhound 'Braxton' wears boots to protect his paws from ice melting chemicals during his morning walk as the temperature hovers in the single-digits Fahrenheit January 22, 2014 in Washington, DC. After four inches of snow fell on some places in the capital area, the federal government delayed the start of the work day by two hours as most schools remained closed. (Photo by Chip Somodevilla/Getty Images)
A little dog who is blowed by strong wind is watched by a big one during the first snowfall of this year in Bucharest on January 25, 2014. A thick blanket of snow covered Saturday southern and eastern Romania causing the closure of three highways , canceling twenty rail links and disruptions in air traffic. Dozen roads were also closed to traffic Saturday after heavy snowfall since Friday night. . AFP PHOTO DANIEL MIHAILESCU (Photo credit should read DANIEL MIHAILESCU/AFP/Getty Images)
Two pug dogs are walked in the snow in Travemuende, northern Germany, on March 29, 2013. Meteorologists forecast temperatures around freezing pont for the coming week in Germany. AFP PHOTO / Ole Spata GERMANY OUT (Photo credit should read Ole Spata/AFP/Getty Images)
A Beauce Sheep dog covered by snow is pictured on March 12, 2013 in Godewaersvelde, northern France, after a heavy snow storm. Overnight on March 12 nearly 500 cars were blocked near Cherbourg where snowdrifts piled up 60 centimetres (almost two feet) as winds reached 100 kilometres (more than 60 miles) an hour. Twenty-six regions in northwest and northern France were put on orange alert because of heavy snowfalls, which Meteo France said were 'remarkable for the season because of the expected quantity and length of time'. AFP PHOTO PHILIPPE HUGUEN (Photo credit should read PHILIPPE HUGUEN/AFP/Getty Images)
ST MORITZ, SWITZERLAND - JANUARY 25: A pug dog is seen during the Polo World Cup on Snow match between team Ralph Lauren and team Cartier on the frozen Lake St Moritz on January 25, 2013 in St Moritz, Switzerland. (Photo by Lars Baron/Bongarts/Getty Images)
LAUDER, UNITED KINGDOM - JANUARY 21: Tim Coulson huntmaster and Victoria Walton at the Lauderdale Hunt exercises the hounds in the snow at Scarce Law on January 21, 2012 in Lauder, Scotland. Widespread snowfall is affecting most of the UK with school closures and transport disruption. The Met Office has issued a red weather warning for parts of Wales, advising against all non-essential travel as up to 30cm of snow is expected to fall in some areas today. (Photo by Jeff J Mitchell/Getty Images)
A dog named 'Lucky' runs through the snow on the frozen lake Helenesee near Frankfurt (Oder), eastern Germany, on February 12, 2012. Temperatures remain cold in Germany as the death toll from Europe's big freeze rose past 550. AFP PHOTO / PATRICK PLEUL GERMANY OUT (Photo credit should read PATRICK PLEUL/AFP/Getty Images)
Dogs play in the snow on the Sandringham estate in Norfolk on February 5, 2012. AFP PHOTO/BEN STANSALL (Photo credit should read BEN STANSALL/AFP/Getty Images)