Many dog owners believe their pets are able to pick up on their moods, but scientists have demonstrated once and for all that man's best friend can actually recognise emotions in humans. Researchers found that by combining information from different senses dogs form abstract mental representations of positive and negative emotional states in people.
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 behaviour 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. The dogs used in the testing were unfamiliar with the procedure; avoiding any chance of conditioning. The vocalisation 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 vocalisation, 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.