By Dr. Becker
Does your dog ever look you in the eye and seem to know exactly what you're thinking? This isn't all in your imagination. Dogs are keen observers and have adapted to living closely with humans for more than 10,000 years.
New research published in the journal Current Biology confirmed that pet dogs can, indeed, discriminate emotional expressions in human faces.1 A group of dogs were first trained to associate pictures of happy or angry faces with a treat reward.
The dogs were shown pictures of half faces (either the upper half or lower half of a face) showing happy or angry emotions. Half were given a treat when they touched their nose to a happy face while the other half were rewarded for touching the angry faces.
The dogs were then tested using pictures of faces they hadn't seen before or showing parts of the face that were new to the dog (so a dog that had previously seen the lower half of a face would be shown the upper half).
The results showed the dogs were quite clever and able to differentiate between the different emotions.
Dogs Likely Can Discriminate Between Happy and Angry
Dr. Kun Guo, a psychologist and expert in Human-Animal Interaction from the University of Lincoln, told BBC News:2
"Showing dogs only half of the face and then the other half separately means they can't rely on the shape of the eyes or the mouth — they must have some sort of template in their mind … So it looks like they can really discriminate between happy and angry."
The researchers speculated that dogs probably used their memories of real emotional human faces to help them complete the experiment successfully. Interestingly, during the training portion of the study it took the dogs about three times longer to learn to touch an angry face.
The researchers said it seemed as though they didn't like to touch an angry face, and perhaps they really have an understanding that an angry face is something they do not like.3 Another thing dogs seem not to like? People who are mean to their owners.
Dogs Snub People Who Are Mean to Their Owners
Research led by Kazuo Fujita, a professor of Comparative Cognition at Kyoto University, showed that dogs will refuse food offered by someone who was uncooperative to their owner.
For the study, dogs watched as a person either helped their owner open a box, actively refused to help with the task, or behaved in a neutral manner. The strangers then offered food to the dog.
It turned out the dogs were more likely to choose food being offered by the neutral party and refuse food offered by the uncooperative party.4
The study shows the dogs make social and emotional evaluations of people and may make decisions based on those evaluations, even if it doesn't benefit them directly. Fujita told Discovery News:5
"We discovered for the first time that dogs make social and emotional evaluations of people regardless of their direct interest … This ability is one of key factors in building a highly collaborative society, and this study shows that dogs share that ability with humans."
Dogs Will Stop Trusting a Person Who Lies
Separate research has even shown dogs learn when a person is not trustworthy and no longer follow their commands. In one study, all dogs initially went to a container that a researcher pointed to, under which a bit of food was hidden.6
The researchers next pointed to an empty container after showing the dogs that food was hidden under a different container. Then, in the final phase, the researchers again pointed the dogs toward the correct container with the hidden food.
However, by this point the dogs were no longer willing to trust him and only 8 percent went in the direction he pointed. According to the study:
"These results suggest that not only [are] dogs … highly skilled at understanding human pointing gestures, but also they make inferences about the reliability of a human who presents cues and consequently modify their behavior flexibly depending on the inference."
Your Dog Listens When You Talk
The average dog understands about 165 different words, although they may learn many more if you train them to.7
It's known that dogs pay attention to the tone of your voice, the pitch and the rhythm in your speech, and research suggests dogs also sense a difference between the verbal and emotional components of speech.8
Dogs appear to process emotional cues and meanings of words in different hemispheres of the brain, similar to humans. Dogs also pay attention to your body language, taking note of your posture and eye contact, for instance.
Dogs will follow your gaze similarly to a 6-month-old infant, but only if you convey the intention of communication, which suggests they're quite in-tune with your communicative signals.9 Dogs have even been shown to experience cross-species empathy in response to a crying baby.
In humans, levels of the stress hormone cortisol tend to rise in response to an infant crying, which is said to be a primitive form of empathy. Research shows that dogs, too, experience increases in cortisol levels when a human infant cries.
Dogs also displayed a combination of submissive and alert behavior in response to the cries. According to the study, published in Behavioral Processes:10
"These findings suggest that dogs experience emotional contagion in response to human infant crying and provide the first clear evidence of a primitive form of cross-species empathy."
Taken together the research suggests dogs and humans have developed many forms of communication that allow us to understand one another. Of course, if you're a dog owner you probably knew that already.