Last word Animal Cognition
Washington Since humans have no tails to wag, they need to look at their best friend for signs they feel happy, scientists say.
Researchers at the Azabu University in Japan found that dogs have bec
ome so attuned to living with humans that they even distinguish a smile, even on the faces of some strangers.
Dogs, they said, have an innate ability to recognise each othersexpressions, but over time they also learned to interpret faces of a completely different species, humans, Live- Science reported.
For the study, the team led by Miho Nagasawa, trained nine pet dogs using photos of their owners, who were smiling in some of the photos and looking neutral in the others.
The dogs were trained to touch their nose to photos of their owners smiling face. Only five of the dogs completed this training.
These dogs were then shown photo pairs of smiling and blank- expression faces of unfamiliar people as well as of their owners.
When shown photo pairs of either their owner or a stranger who was the same gender as their owner, the dogs selected the smiling faces more often than would be expected if they were randomly choosing a photo.
Dogs may be picking up on obvious differences in facial features between the smiling and blank faces, such as the exposed teeth associated with smiling, the researchers believe.
Detailing their findings in the July issue of the journal Animal Cognition, the researchers wrote: This study has shown that dogs that live closely with humans are also able to recognise positive facial expressions, indicating that these dogs have acquired the social skills helpful to survive.
The ability to learn to discriminate human facial expressions must have helped dogs to adapt to the human society. Monique Udell, who studies canine cognition and behaviour at the University of Florida, said: We know that dogs are very good at picking up on subtle cues given by humans, but often those involve movement and occur in the presence of the actual person. It is interesting that picture discriminations of this type can be trained in dogs as well. Udell, who was not part of the research, also said the ability to recognise human facial expressions, along with other human cues, is not innate.
Instead, dogs acquire the knowledge as they come to associate certain expressions with either a reward or a punishment, she said.
However, the researchers said that the dogs have limits in their recognition abilities.
In another test, when the gender of the person in the photos switched, the dogsperformances dropped.
It is possible that facial expressions differ between men and women or that the dogsclose relationships with their owners interfered with their ability to recognise smiles on the faces of the opposite gender, the researchers added.
This study has shown that dogs that live closely with humans are also able to recognise positive facial expressions, indicating that these dogs have acquired the social skills helpful to survive. The ability to learn to discriminate human facial expressions must have helped dogs to adapt to the human society. ANIMAL COGNITION| JOURNAL