Most of the research on posture and public speaking has focused on two aspects of body language that seem to offer opportunities for improvement with relatively little work.

First of all, there’s all the study of what Amy Cuddy calls “power poses.” The idea is to stand up straight, or to take up more space by putting your hands on your hips like Wonder Woman, or to smile broadly to indicate confidence. The basic idea with all this conscious positioning of the body is that if your mind finds you standing or smiling confidently, you’ll feel more confident.

Cuddy’s initial research seemed to show that merely standing powerfully would cause your body to issue more testosterone and less of the stress hormones. Subsequent research failed to support these initial findings, but participants do report reliably feeling (subjectively) better. So if power posing makes you feel better, there’s no reason not to do it.

The second aspect of body language research and speaking in this regard focuses on how your posture and gestures influence not yourself but other people – the audience.

Here the findings are more nuanced and complicated, but summing up, openness of the speaker’s body language, and her closeness to the audience both improve its positive reception of and higher ratings of the speaker.

In short, then, the research suggests that before the speech you should practice powerful poses in order to make yourself feel more confident, and during the speech you should focus on staying open and moving toward the audience to the extent possible, without actually sitting in their laps.

But there’s a catch. You didn’t think it would be that easy, did you? A new study found that students who relaxed their body language – slouched, in fact, in comfortable chairs – freed up more of their cognitive power for solving math problems. If the same students were made to focus on sitting up straight at their desks, they had fewer brain cycles to spare and performed more poorly on their exams.

What this research suggests is that focusing on body language with your conscious mind – activity normally left to the unconscious mind – takes some brain cycles away from thinking about the content of your speech, or anything else, for that matter.

Your conscious mind can handle something like 40 bps of information. That’s not very much, and so normally most of the important work of keeping you going, walking, talking, and chewing gum falls to your unconscious mind, which can handle something like eleven million bps. If that unconscious mind operated in such a way as to cause you to naturally adopt a power pose before you spoke, and then stay open and close to your audience while speaking, you wouldn’t have to think about it (consciously) and public speaking would be a little easier.

But unfortunately, the instinctive behavior of the unconscious mind is to retreat from and close off from large crowds, in order to play it safe. And power poses? Not so much. More like their opposite, the hide-in-a-corner-in-a-fetal-position pose comes to mind.

So to learn to speak well and successfully, in addition to mastering your content, figuring out what to wear, and a host of other desiderata, you need to shift responsibility for your body language and posture to your conscious mind – preferably while practicing your speech adequately – for as long as it takes to ensure a good result during the actual speech.

One thing is sure. If you avoid thinking about your posture and body language, and leave it to chance, then you will get the instinctive body language and posture that humans have evolved to respond to threats with: self-protective, withdrawing, and timorous. Is that the persona you wish to project?

We’ll be talking about successful body language at our one-day conference on Powerful Public Speaking in Boston on October 28th.  Sign up here.