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Just How Happy Is Your Dog? It May Take a Quick Eye to Know

Micro-expressions on a dog's face indicate its emotional state

Llima Orosa photo -- Creative Commons Licence
Source: Llima Orosa photo -- Creative Commons Licence

Your dog is communicating to you all the time, mostly about his emotional state and his attitudes toward what he is currently viewing. Some of these messages are quite obvious to someone with a little bit of knowledge about canine behavior — such as the dog' s tail movements, overall facial expressions, various sounds such as barks growls whines and whimpers, or his general body posture.

However there are some ways that dogs communicate which are extremely subtle. It takes a bit of training and a vigilant observer to catch these fleeting signals as they fly by.

I was reminded of this when I attended a research conference and encountered a colleague I hadn't seen in a couple of years. His area of specialization is the study of human emotions — how they are expressed and how people tend to perceive such emotional signals. We had a bit of free time between sessions so we sat down (with the ever present coffee in a cardboard cup) to chat about some personal and professional matters. He was quite excited about a recent series of workshops that he had given for CSIS, the Canadian Security Intelligence Service (equivalent to the CIA).

The workshops he had given involved training agents to recognize the subtle, involuntary, facial expressions of emotion called micro-expressions. Such emotional responses were extensively studied by Paul Ekman, a professor emeritus at the University of California at San Francisco. Micro-expressions can occur when a person is consciously trying to conceal any sign that would show how they are feeling or even in cases when a person doesn't consciously know how they are feeling. They are quite different from regular facial expressions in that it is difficult, if not impossible, to hide these reactions. This is partly because they happen in a fraction of a second. Such expressions can clearly be read if the person's facial movements are photographed with a high-speed camera, but even in the absence of such equipment it turns out that people can be trained to detect and interpret micro-expressions that occur in real-time. This is an extremely useful skill for police and security personnel, especially in areas where there are real concerns about terrorism. A good interpreter of micro-expressions might not be able to tell you what a person is thinking, but he can give you a good estimate as to what that individual is feeling. That skill can also provide a clue as to whether or not a person is lying, an imperative ability for law enforcement personnel when they are interviewing someone.

There are number of skills involved in reading micro-expressions. First, it is useful to know that the most informative of these expressions tend to occur in the upper part of the face, including signals associated with regions around the eyes, the forehead, and sometimes the nose. Also, agents must be taught to recognize asymmetrical expressions. An expression that is more pronounced on one side or the other can tell you something about emotions because the left and right hemispheres of the brain tend to favor processing different emotional states. Since the left brain controls the right side of the body and the right half of the brain controls the left side of the body, you can gain information about emotional states by noting whether an expression occurs predominantly on one side or another. This is also shown to be the case in dogs; Data shows that dogs tend to wag their tails with a bias toward the right or the left side of their bodies depending upon what they are feeling at the moment,

My colleague paused for a moment to ask me, "I know that dogs have a number of readable facial expressions. I was just wondering if they also have the kind of micro-expressions that humans do. The reason that I'm asking is because it would be useful information for people who work with dogs professionally, or those who simply have to interact with them, like postal delivery people."

It turns out that some research has been done on this question by Miho Nagasawa of the Department of Animal Science at Azabu University in Sagamihara, Japan and it has been published in the journal Behavioural Processes. Like most studies of human micro-expressions, the dogs' faces were photographed by a high-speed camera. Also, like some of the human research, colored tags were placed on the dogs' faces over particular muscles to allow the facial movements to be more precisely tracked and interpreted.

The research setup involved 12 dogs, each of whom was placed in a room divided by a partition that contained a cut-out window. Through the window could be seen an opening which was covered by black curtains that could be opened briefly so that a dog could glimpse what was on the other side. In some instances, when the curtains opened the dogs would see their owner. Alternatively the curtains could open to reveal a stranger. At other times what the dogs would see when the curtain opened was an item that their owner had brought along and which the owners knew that the dog either liked or disliked. The positive item might be a favorite toy, while the negative item might be something dreaded, like nail clippers.

The results indicated that dogs do have micro-expressions which differ depending upon what they are looking at. For example, within a half a second of seeing someone behind the screen the researchers found that dogs moved their eyebrows upward. However there was a side bias in this response: Whenever dogs saw their owner they lifted their left eyebrow higher than the right. You can see how researchers tracked this quick movement in the figure here.

Miho Nagasawa, Azabu University
Source: Miho Nagasawa, Azabu University

Since the right hemisphere of the brain is usually associated with more positive "approach" behaviors, the researchers interpret this response as indicating that the dogs were happy to see their owners.

There was also a distinctive micro-expression when the animals were introduced to someone they had never met; however in this case, it involved the ears. When viewing a stranger, the dogs moved their left ear back and down slightly. In the more commonly observed emotional expressions of dogs, moving the ears down or back is interpreted as a sign of insecurity or hesitancy. So the researchers suggest that this might simply be a quick fraction of that more familiar ear signal.

Finally the researchers noticed that when the liked vs. unliked objects were presented, only the response to the unwelcome object produced any noticeable response: When presented with something they found unpleasant, there was a momentary flick of the right ear.

It is not clear why these particular micro-expressions showed up. Since this research concentrated on the upper half of the dogs' faces, particularly the eyebrows and ears, it is possible that other micro-expressions were occurring but not recorded; further research is clearly needed. This recent study does confirm, however, that just as in humans, quick, subtle, expressions can be read from the dog's face which give us a hint as to what their emotional state is.

After our discussion, I went home and tried observing similar micro-expressions in my own dogs when they were confronted with things that I knew that they liked or did not. I regret to say that my dogs were bouncing around too quickly, or maybe my old brain was not processing fast enough; I couldn't be sure that I really saw the same facial changes that the high-speed camera picked up. But I anticipate that I will see my colleague again at another conference sometime, and I think that maybe, if he is done educating people involved in security and law enforcement, perhaps I could convince him to give a quick workshop to teach some doggie researchers the tricks needed to see the micro-expressions on dogs' faces. Until then I will simply keep looking to see if I can detect anything on my own, now that I know that they are there.

Stanley Coren is the author of 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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Miho Nagasawa, Emi Kawai, Kazutaka Mogi, Takefumi Kikusui (2013). Dogs show left facial lateralization upon reunion with their owners. Behavioural Processes 98, 112– 116.

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