Just by looking at photos of people faces, and even parts of faces, dogs can tell when we are happy or upset, researchers from the Messerli Research Institute and the Clever Dog Lab at the Vetmeduni Vienna, both in Austria, reported in the journal Current Biology.
Corsin Müller, Ludwig Huber and colleagues set out to determine how good dogs were at distinguishing happy and unhappy human faces just by looking at pictures.
Their twenty participating canines were presented photos of angry and happy women’s faces on a touchscreen.
The dogs were able to distinguish between photos on the touchscreen of happy and angry eyes. (Image: vetmeduni.ac.at)
The dogs were split into two groups: One group was rewarded to touch the images of happy faces, while the other was trained to do the same with the angry faces.
The researchers went a step further and factored out conspicuous differences between happy and sad faces, such as frown lines or teeth, and split the images horizontally so that during the training phase the dogs could only see either the eye or mouth region.
Even with just parts of the women’s faces shown on the photos, the majority of the dogs were able to differentiate between the happy and angry images.
They were also good at picking out angry and happy images when presented new pictures of face halves of people they had not seen during the training phase.
Dogs prefer happy faces
Unsurprisingly, it was easier to train the dogs to pick out the happy faces than the angry ones, i.e. it took less time to teach them to select the happy images.
Just with photos of women’s mouths, the dogs could tell which ones were of happy or angry faces. (Image: vetmeduni.ac.at)
Study director Ludwig Huber said “It seems that dogs dislike approaching angry faces.”
First author Corsin Müller said:
“We believe that dogs draw on their memory during this exercise. They recognize a facial expression which they have already stored. We suspect that dogs that have no experience with people would perform worse or could not solve the task at all.”
Dogs’ visual perception better than previously thought
We have always known that a dog’s sense of hearing and smell is much better than a human’s, but the spatial resolution of their vision is about seven times lower.
Huber said:
“It had been unknown that dogs could recognize human emotions in this way. To better understand the development of these skills, we want to perform similar tests also with wolves at the Wolf Science Center.”
As part of the WWTF project “Like Me”, Ludwig Huber and colleagues have spent the last three years trying to determine whether dogs can undertand the emotions of conspecifics or of people. WWTF (Wiener Wissenschafts-, Forschungs- und Technologiefonds – Vienna Science and Technology Fund) is a non-profit organisation established to promote science and research in Vienna.
Citation: “Dogs Can Discriminate Emotional Expressions of Human Faces,” Corsin A. Müller, Kira Schmitt, Anjuli L.A. Barber and Ludwig Huber. Current Biology. DOI: http://dx.doi.org/10.1016/j.cub.2014.12.055.