We all know that. And when we speak, we can get hung up on what our gestures are saying. There are, in fact, a lot of people who make money giving advice to speakers about using appropriate gestures. That makes us all doubt ourselves. Are our gestures "giving us away"?
This micromanagement of gesture is very old. Back in the days before microphones, speakers did have a specific gestural vocabulary that they employed. One of the reasons they needed to use it was so those in the back could at least "see" some of what they were saying. This practice was called chironomia, and it traces its origins to the ancient Greeks and Romans.
Today, body language and gesture are used to convey confidence and focus. If a speaker is using gestures that are not congruent with her message—for example, if she is very inviting with her words and has a warm tone, but is gesturing with downward hand chops—we wonder if she really believes what she is saying. Or if he is presenting a stern ultimatum using open palm gestures, maybe he is not really feeling as committed as his speech indicates.
And then there are the "empty" gestures that someone decided looked like they meant something but really don't. Politicians have a big vocabulary of these! My favorite is the "politician's thumb"—the gesture JFK is thought to have originated that Bill Clinton perfected. It is intended to be a polite gesture of power (which in itself is contradictory), unlike straightforward finger-pointing. So it has won a permanent place at the political podium. The mythical President Frank Underwood uses it a lot this season on House of Cards. I have noticed, though, that his usage of this thumb thing increases as he feels his power slipping away.
There are other specifically political gestures that my candidate clients have been told (by others) to use, like steepling fingers together, or "holding the melon" in front of you when standing. When I ask them what these mean, they usually reply they are trying to "show" something. I don't doubt that is what they were told. But my acting training has taught me that "showing" is never as effective as "being." In fact, "showing" usually conveys some falsehood or pretense. In this case, it means you feel a need to use your hands to convey a confidence you don't really feel, and are not sure how. So you fall back on something you have been told has worked. For others. In the past. If you can't own these gestures, and know what they mean to you, they are less than useless. If you don't know what to do with your hands, don't use 'em. Gesturing for the sake of gesturing just calls attention to your discomfort in the situation.
The goal, whenever you are speaking, is to be open, relaxed, confident. You get that way by being centered and physically grounded. So you stand tall and gesture appropriately. Don't slap some random, inorganic, impersonal gesturing on top of your speech and think it will work. No matter how many experts tell you it will, when you have real people watching—it won't.
Illustration from A Manuel of Gesture by Albert M. Bacon, 1875