“Micro-expressions” - sounds like something you might see if you’re looking at some highly caffeinated cells through a microscope right? Actually, the term micro-expressions is about tiny facial muscle movements that most of us can’t easily control. Because we can’t control them, they sometimes express what we’re really feeling and thinking more than words and actions do.

In fact, these quick movements (up to about ¼ second in length) sometimes tell the most authentic story about what’s going on in a person’s head or heart.

Paul Ekman is a psychology professor at the University of California. He’s done his homework on this kind of thing and says it’s not the shifty or averted eyes that will tell you a person’s lying. And happiness is not really expressed by just showing a few teeth. To really understand what’s going on, you have to look at the little tics and twitches that a person is not aware of, especially in the upper half of the face, which is harder to voluntarily control.

For example, we tend to look for happiness in a person’s smile, but it really shows in the eyes. Also look for crinkled skin around the edges of the eyes and eyebrows. If it’s genuine, the corners of the mouth will be turned up. A fake smile shows teeth, but the top lip will look more horizontal.

If there is disgust, the person often narrows the eyes and wrinkles the nose. Contempt, on the other hand, usually shows as one side of the mouth moving upwards, possibly with a sneer.

However if, for example, someone looks fearful when explaining to you why they did or didn’t do something, it doesn’t necessarily mean they’re not telling the truth. The person might simply be scared that you’ll get angry or you won’t believe them. This is a good illustration of the usefulness of studying micro-expressions: to recognize patterns and help you understand someone else’s motivations - and not to judge other people.