A new study suggests that the domestic dog has the ability to recognize and distinguish the different states of mind in humans, The Bulletin reports.

The research study showed that dogs make the use of facial expressions and voice characteristics as indicators of the human's state of mind.

The study noted that while the ability to detect the mood of another is common enough within the same species, dogs appear to be unique in sharing with humans the ability to transcend the boundaries of species in studying emotions.

The study was published in the journal Biology Letters.

Researchers from the University of Lincoln in Britain and the University of São Paulo in Brazil led the study to describe the method of demonstrating dogs' knack for reading the emotions of others.

"Previous studies have indicated that dogs can differentiate between human emotions from cues such as facial expressions, but this is not the same as emotional recognition," said Kun Gou from the University of Lincoln.

"Our study shows that dogs have the ability to integrate two different sources of sensory information into a coherent perception of emotion in both humans and dogs. To do so requires a system of internal categorisation of emotional states."

The study noted that the methods by which dogs study emotions closely resembles methods used to demonstrate social understanding in preverbal human babies.

For the study, the researchers studied17 healthy socialized adult dogs and presented the dogs with combinations of images and sounds.

The researchers noted that the length of time that a dog looked at an image offered insight into whether the dog attached social meaning to the emotion being conveyed and whether he or she integrated stimuli from different sources in doing so.

The authors suggested that a dog with a knack for recognizing humans' emotions would fare better in getting protection, shelter and even food from humans.  The authors noted that the trait to recognize emotions of humans must have been favored as selective breeding and domestication of dogs spread among human communities.

The ability to derive emotional information by combining visual and auditory indicators "suggest(s) cognitive capacities not previously demonstrated outside of primates," the authors wrote.

"Further, the ability of dogs to extract and integrate such information from an unfamiliar human stimulus demonstrates cognitive abilities not known to exist beyond humans."