Dogs can read the smile on your face… your dog reads you like an open book. You think your dog doesn’t know how you feel? You’re wrong! A new study proves that dogs can recognize emotions just by looking at a human’s face. When we look at a photo of a human face, we can easily recognize the emotional state of that person simply by their expression. And in the same way, dogs can too.

Several years ago, a person visited the lab of a friend, a well-known researcher in the field of human emotion. He was setting up an exhibit and had prepared several large-scale photographs of people showing a variety of emotional expressions. He had propped them up against the wall so that he could select the ones he would use in his exhibit. This person had his beagle dog, Dante, with him, and as dogs do, he walked around the photographs sniffing them as he looked at them, until he came across a photograph showing an aggressive expression. At that point, the dog stopped, looked at the photograph more closely, and then backed away and would not approach the photograph again.

Could a dog read the emotion in this aggressive expression or was it simply avoiding the photo? At the time, there was no evidence that dogs had the ability and sensitivity to read emotions based solely on the expression displayed on a human face. Since then, however, researchers have discovered that dogs are indeed able to differentiate emotions from photos of faces alone.

There is no doubt that dogs watch humans, read their emotional reactions, and modify their behavior based on what they see. If you observe a dog owner being anxious around humans, or anxious and avoiding crowds, don't be surprised to see the same nervous and uncomfortable behavior in their dog. That dogs interpret their owner's emotions and connect them to the things that person is reacting to has been proven in the lab.

One study that was done involved having a dog and its owner enter a room with an oscillating fan on the floor. The fan was hung with plastic streamers and they fluttered in the wind as the fan spun rapidly. If the dog's owner approached the fan and seemed interested and amused, the dog responded positively as well. The dog was then apt to approach the fan with a curious and interested demeanor. On the other hand, if the person responded in a fearful, anxious, or uncertain manner, then the dog tended to stay away in a corner and treated the fan as something that made it nervous and uncomfortable. The researchers used more than just photographs of human faces. Not only did the researchers study facial expressions, but they also used voices and body language to convey negative and positive emotions. To correctly interpret an emotion simply by looking at a face, such as in a photograph, requires a fairly subtle level of interpretation. However, a new study has shown that dogs are capable of doing exactly that!

The new study in question has been accepted for publication in the journal Current Biology, and was designed to determine whether dogs could actually read human emotions just by looking at a person's face. The team of researchers was based in Vienna. They trained a group of 11 dogs to distinguish between pictures of the same person and whether that person had an aggressive or happy face. The first thing to note is that the dogs couldn't see the entire face. Each dog was only allowed to look at the top of the person's face or the bottom of the person's face. For each dog, an aggressive or happy expression was chosen to be considered the correct one, and the dog had to indicate the face by using its nose to touch the picture that showed the requested expression. The faces were shown in pairs, and giving the correct answer earned the dog a reward.

Some of you may think that the fact that dogs can learn to tell the difference does not necessarily mean that they can automatically read and interpret people's emotional expressions, but rather, that they can learn this skill. However, the tests went much further than that. The most interesting finding came after the training phase, during which the dogs proved to be able to distinguish happiness from anger just by looking at the top or bottom of a face. In the next test, the dogs were able to see the other half of the face or halves of unfamiliar faces; and the dogs were again able to determine the happy emotion from the aggressive emotion simply by looking at the mouth.

The dog seems to be able to distinguish and connect a smiling mouth to smiling eyes. The dog's ability to read human facial expressions lies in their prior knowledge of the meaning of human emotional expression. The dogs could have solved the task simply by applying their knowledge from the beginning. The study demonstrates that dogs can differentiate a happy face from an aggressive face in humans. They can sense that these two emotions have different meanings and they can do this not only with people they know, but also with those they have never seen before. It seems that dogs are able to associate a happy face with a positive meaning and an aggressive face with a negative meaning.

What's particularly interesting is that the researchers report that the dogs were much slower to learn to associate the aggressive face with a reward. This most likely means that the dogs already had an idea, based on their previous experiences, that it's best to stay away from people when they appear angry. This means that asking them to approach and touch the aggressive face for the sole purpose of getting a treat conflicted with their primary instinct to avoid such people and stay away. They all seem to have learned that good things happen to them when they're around happy humans, while bad things can happen to them when they're around aggressive humans.

Here's something to remember: When it comes to expressions, you'll catch more flies with honey!