Anyone out there remember “Lie to Me”? It is a TV series about a group of psychologists who solved mysteries by decoding the micro-expressions of various players until they unraveled the problem or found the missing person or whatever. That’s where I first heard of micro-expressions, which are involuntary and almost imperceptible facial expressions that express a person’s emotions — before the person consciously arranges her features to show whatever she thinks she’s feeling or wants others to see. Micro-expressions most often occur when a person is trying to hide her true feelings — or is lying, which is the premise of the TV series.

Turns out, dogs have micro-expressions too.

These are similar to — but far more subtle and easier to miss than — calming signals. Calming signals are dog body language cues that offer insight into how the dog is feeling, and they can be involuntary. But dogs can actively choose to offer calming signals, and they often do so — to other dogs and to humans, as targeted communication. But even involuntary calming signals are communicative. Examples of calming signals are the lip-licks and yawns of a stressed dog. These serve to both self-soothe (calm the dog) and tell others that she’s stressed. More examples are given in Please Back Off.

Micro-expressions in dogs, according to research done in Japan, are similar to micro-expressions in humans; they are fleeting and very easy to miss. But they also reveal preferences and can show an astute observer whether a dog is happy about something or feeling fear or dread. The researcher, Miho Nagasawa, has also studied the link between oxytocin level and dog-human interactions (dogs’ oxytocin levels rise when they gaze at their owner or interact; people’s oxytocin also rises when they stroke a dog).

Back to micro-expressions. Dogs show, with quick ear flicks, if they find something (or someone) unappealing or frightening. They show, with a quick eyebrow raise, pleasure at the sight of their human or a favorite toy. The images were captured with high-speed cameras, and are probably too fast for most of us to notice. You can read more about it in Dr. Stanley Coren’s blog post, “Just How Happy Is Your Dog?”

As with MRI studies by Dr. Gregory Berns, the research points to more and more ways that dogs and humans are alike in how we experience and show emotions. I don’t find the similarities terribly surprising, but I do think that the more we learn about how dogs (and other nonhumans) think and feel, the harder it will be to justify or excuse much of our terrible treatment of them. It also offers a great excuse for spending time just watching your dog … you both get that nice oxytocin boost, and you might observe some fleeting body language cues that will help you understand your dog better!