There's a little thing called a microexpression. It's a tiny expression of emotion, lasting a fraction of a second. A give-away to what's going on inside. It may be a flicker of an eyebrow. Or a tensing of the muscles around the lips. A blink or a downward glance. A slight narrowing of the eyes. It's very quick, a fraction of a second, but most people watching are sensitive to even the tiniest flicker, even if they are not conscious of them, and although the microexpression and what it means may be individual to each person, it will still be subliminally caught and understood. Most people are not aware of their own microexpressions, and it's very difficult to control.
One day at work two guys came to my office with a proposal. The one guy explained what they wanted to do, and as soon as he was done, without even a pause, he turned to the other guy and said, "I told you she wouldn't like it!"I have a bunch of microexpressions, but being aware of them doesn't make it easy to control them.
I objected. "I didn't say I didn't like it." He responded, "No, but your nostrils flared. You always flare your nostrils when you don't like something."
I laughed, and had to admit that my first reaction was negative, "But let me think about it a while."
He was right. I do make a tiny quick nostril flare when I'm annoyed, in that instant before I take control and don't express that annoyance.
The Wikipedia entry on microexpressions linked above isn't very good, actually. It tends to wander off into general facial expressions of emotion, leaving confusion. The article says that very few people can catch and interpret microexpressions, but I don't agree with that. Have you even spent some time with, say, a couple, and later you conclude that she is afraid of him, and you're worried for her, but if anyone asks why, you don't have an answer? Or you know someone you instinctively don't trust, even though they've never done anything wrong? It's because you pick up on microexpressions, and you don't even realize it.
There are a lot of people who are unpopular, socially isolated, and they don't know why. It can be anything from poor hygiene to no social skills, any of a gazillion reasons - but one of them is likely their microexpressions. They expect people to disappoint them, or to not meet their standards, or to otherwise piss them off, and they SHOW it. Outwardly they are very pleasant, but their microexpressions expose their poor expectations of others, their rejection of them,
and no one likes to be judged