Have you ever watched a situation in which the nonverbal communication seemed almost surreal? One that sticks in my mind occurred when I was a business student. An entrepreneur had come to our class to practice a presentation he would make later to venture capital firms. His product was an enhanced respirator that had the potential to save the lives of many new-born babies.

I observed an almost surreal form of nonverbal communication when I was a business student. At the front of the classroom, an entrepreneur was practicing a pitch he would make later to venture capital firms. Specifically, he was talking about a technology his firm had developed: a respirator which had the potential to save the lives of many infants.

When he talked about the potentially great financial returns, the audience, made up of M.B.A. students, sat back passively. But when he talked about getting babies through critical moments with his respirators, every single person in the classroom sat up, alert and fully focused.

As he went back and forth between stories of saving babies and talking about financial results, almost every student in the classroom moved with him. You might have thought that the movements of the students had been choreographed according to the content of the pitch.

They sat up together when the entrepreneur talked about saving babies, and they sat back in unison when he discussed the numbers. And, by the way, I did it too until I become aware of how we were responding as a group.

I've believed firmly in body language since then, body language being a form of nonverbal communication in which people consciously, but more often unconsciously, show what moods or emotions through body movements.

As you likely know, interpreting body language is part science and part art. Still, some basic gestures will give us insight into the emotions or moods of others. A few examples of this form of nonverbal communication follow.

Crossed arms, as almost every salesperson knows, means the person on the other side of the table is defensive or not receptive. On the other hand, if that person leans forward and keeps his or her eyes on you, then you do have a receptive listener.

Novice speakers, for instance, often show a lack of confidence by keeping their arms in tight to their bodies. As they get more practice speaking in public, you'll see their arms move away from their sides and become active tools for conveying messages.

Arms wide open indicates trust and openness, as do open hands, while arms held high above the head show a sense of victory, and hands clenched indicate anger.

Curiously, one of the most difficult interpretations of body language involves lying. Researchers have probably spent more time on this aspect of body language than any other. And we're still not entirely sure what body language to trust when it comes to truth and trust.

If you haven't yet spent much time studying body language, I recommend that you add it to your to-do list for communication development. It's invaluable not only for speaking and listening, but also for negotiating and leading.

Summing up, body language, a form of nonverbal communication, gives us insight into emotions or moods, and helps us send and receive messages more effectively.