This is useful to everyone, especially in a career world that is so overwhelmingly global.
You'll find "experts" on body language and rants about the meaning of this gesture or that one. Much of this is true, with one huge caveat: you have to be patient and carefully synthesize the totality of the gestures and mannerisms in order to develop some degree of accuracy.
If you are making a presentation, running a meeting, or in a management discussion, it may be more helpful to know what emotions are universal. This gives you a better chance at narrowing the possibilities of what kinds of responses you are really seeing. So, here goes.
The Seven "Universal" Emotions
These are common throughout all people and cultures:
There are 10,000 different facial expressions. About 3000 of these facial expressions are relevant to emotion and most people use only 50-60 in normal conversation. Those 50-60 do relate to the seven universal emotions.
These expressions can be "macro" expressions which last 1-3 seconds or even longer. An example would be a smile. The question: "Is the smile real or fake?" If fake, what does that mean? (Sometimes a cigar is just a cigar; people simply want to be polite).
We also make micro expressions that give up our more hidden feelings. These are like reflexes, because it's very difficult to stop them from happening since they are part of our brain's hard-wiring. That's why we get a "feeling" when we watch small discrepancies between someone's words and their expression.
These expressions last only 1/25th of a second. (That is faster than an eye-blink). Most people can't pick up micro expressions consciously. When viewed on film and played as slower speeds, these expressions look just like macro expressions. Many homicide detectives do this. If you don't happen to be looking for a serial killer, it's still a great way to watch what signals you give off when you are speaking or running a meeting.
How to Use This
The seven universal emotions are the ones that are most important to you. You want to know whether someone is angry, happy, etc., with your interaction. Memorize the list (or carry a cheat sheet) and increase your awareness of these.
Do: When you think you have enough visual information to believe that the person--or people--are, say, "surprised", don't make the assumption that you are correct. Instead, matter-of-factly state your observation: "You know, I'm watching the response to this slide and am getting the sense that maybe you are a bit surprised. Is that so?" This will lead to affirmation or will yield other responses that will help you--and them--stay or get on track.
Don't: Try to be magically clever and tell them you know how they feel. The last time you did that with your spouse or significant other, how'd that work for you?