Have you noticed how people change when they make a presentation? They tend to move from spontaneous to very mechanical. From humourous to serious. From smiling to deadpan. Why do we do this? It shouldn't be that way. Our presentation guru Eric Bergman says you need to be yourself to communicate effectively.

When seeking body language advice for presentations, perhaps the best place to look is in the work of psycholinguists. Psycholinguists study the psychological and neurobiological factors that enable humans to acquire, use and understand language. It has been a recognized field of social psychology for about fifty years.

After more than 30 years of study, Professor David McNeill of the University of Chicago has concluded that people communicate best when they create unconscious and spontaneous gestures. The key words here are "unconscious" and "spontaneous." If you attempt to create gestures to convey the right image, you are neither "unconscious" nor "spontaneous." You're simply not being yourself. If you're not being yourself, you are not communicating your personality. And if you don't convey your personality, the audience will be skeptical of your message.

In her book Hearing Gesture: How our hands help us think, psycholinguist Susan Goldin-Meadow points out that no culture has been discovered in which people do not move their hands as they talk. According to Dr. Goldin-Meadow gesture and speech form a single, unified system.

The evidence also indicates that spontaneous, unconscious gestures make it easier to think. In her research, Dr. Goldin-Meadow has discovered that when the act of speaking becomes difficult, speakers seem to respond by increasing their gestures. Attempting to reduce or eliminate gestures (for example by being told not to gesture as much by a presentation consultant trying to get you to convey the "right image") makes it more difficult to think of what you're trying to say at the times you need all your wits about you.

Professor Goldin-Meadow believes that to "ignore gesture is to ignore part of the conversation." Her research has led her to the conclusion that first, the act of gesturing facilitates communication by promoting spatial thinking, and that, second, attempts to stifle gestures inhibit someone's ability to think.

So what's the bottom line with presentations? Be yourself. Be on your best behavior—there are certain parts of your anatomy you don't want to scratch when you're in front of a group of people—but be yourself.

And your ability to persuade others will be enhanced.