"I don't think that we interpret the emotions in the facial expressions of dogs in any way that is similar to how we interpret those emotions in humans." The man offering this opinion was a highly respected psychologist who had done extensive research and had many publications dealing with how people interpret the emotional expression of other humans.
He went on to say:
"When it comes to human facial expressions, we decipher the underlying emotions automatically. It's really impossible for us to look at a human face without also trying to interpret the emotional expression on that face. I don't think that this is what happens when we look at the faces of dogs. I believe that it is only if we specifically need to know the emotional state of a particular dog that we start to process its facial expression. Then we make an effort to estimate what the animal is feeling based on the information provided by its face. I think that there are certain cues or clues that we look for, but other than that it is sort of like trying to interpret patterns in cloud formations, or what sort of figure might be seen in ink blot."
I had just finished giving an invited lecture in which I had shown a series of pictures of facial expressions in dogs, and I had pointed out the cues that you could use to determine the dog's emotional state. My colleague was objecting to my conclusion that people tend to spontaneously read the emotional expressions in dogs in much the same way that we read the emotional expressions in humans. My interpretation followed in the theoretical footsteps of one of my scientific heroes, Charles Darwin, who in 1872 wrote about the similarities in the ways that both humans and nonhuman animal show their emotions.
Darwin believed that our emotional states automatically trigger emotional expressions in both our faces and our body language. He further went on to suggest that evolution has tuned our brains to interpret such expressions (whether from humans or nonhuman animals) in a similar way. To his way of thinking, we look at a face, regardless of the species that we are observing, we try to interpret the emotions which the individual is experiencing at that moment.
While I believed that Darwin was correct in his theorizing, at the time of this discussion I had no data to support my hypothesis or to contradict what this psychologist was suggesting. In effect, all of our arguments were merely informed bits of speculation. However, science has a way of eventually catching up. Just this week I came across a study which has been accepted for publication in the journal Social Cognitive and Affective Neuroscience* which provides data that could have resolved our argument.
This new investigation was conducted by Robert Spunt, Emily Ellsworth and Ralph Adolphs, all at the California Institute of Technology. They decided to look at fMRI brain scans of people in order to determine if humans use the same mechanisms to interpret emotions from the facial expressions of humans and nonhuman animals. The power of fMRI scans is that they indicate which sections of the brain are most active at any moment.
Eighteen adults served as experimental subjects. These individuals observed photographs of facial expressions of a number of humans. They also viewed photos of nonhuman primates (various apes and monkeys) and dogs (of various breeds). While they were looking at these photographs their brains were scanned for specific areas of increased activity. These observers also saw set of control images that were simply scrambled components of facial expressions, just to make sure that what was going on in the brain had to do specifically with faces and not just the appearance of any visual stimulation.
My colleague felt that we automatically analyze the emotional expressions in the faces of humans, but when looking at dogs, that analysis is only done if we are explicitly asked to look for and interpret the underlying emotions. In this recent study, when the observers passively looked at photographs of human facial expressions with no specific intention to analyze them for emotions, the results showed that activity increased in the expected regions of the brain, the prefrontal and the anterior temporal cortex. This kind of result has been shown in previous research where people looked at human faces.
However, when the observers looked at the facial expressions of dogs and of nonhuman primates, these same areas of the brain were also activated, suggesting that there was no difference in the way that human and nonhuman facial expressions were being interpreted. (These brain areas were not activated when the observers viewed scrambled versions of these images.)
To see if specifically requiring the processing of the emotions behind particular facial expressions made a difference, the researchers gave the observers some tasks involving the analysis of these photos. The observers could be asked to specifically interpret the emotion expressed (annoyed, bored, confident, excited or reflective) or to simply describe the face (baring teeth, gazing up, looking at the camera, mouth closed or mouth open) with no emotional interpretation involved.
Both tasks produced results that were similar to passive viewing. Regardless of whether the investigators looked at the brain responses for the regions of interest in the brain, or analyzed the whole brain's response, they found no evidence for uniquely human emotional processing areas as opposed to areas used to interpret the emotional expression of dogs. In other words, people used the same areas of the brain regardless of the task. This means that we process the emotional content of viewed faces automatically. Ultimately the researchers concluded that "attributions of emotion to both humans and to nonhuman animals draw on the same neural mechanism."
This indicates that when you look at the face of your dog and decide whether he is happy or annoyed, you are using the same regions of your brain to interpret his emotional expression that you would use to interpret the expressions of your friend or lover.
Stanley Coren is the author of many books including: Gods, Ghosts and Black Dogs; The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome
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* Data from: Robert P. Spunt, Emily Ellsworth, and Ralph Adolphs (2016). The Neural Basis of Understanding the Expression of the Emotions in Man and Animals. Social Cognitive and Affective Neuroscience: nsw161v1-nsw161