Yes. It's no myth. Your body can persuade your mind, not just the other way around.
There's some convincing evidence.
As soon as I saw the evidence, I tried it out in one of my presentation skills workshops - and there's no doubting the lift it gave the trainees.
The evidence that body language can boost your confidence
Professor Amy Cuddy, a Harvard research professor, put a group of volunteers through a test. She stood them in a "power pose" for just two minutes, measuring their levels of dominance hormone (testosterone) and stress hormone (cortisol) before and after.
Power pose? There are a few of them, but here's one high-power pose: imagine standing with hands on hips, feet firmly apart, shoulders back, with a relaxed, confident smile, as if you can take anything the universe throws at you. (Low-power? Here's one: sitting with legs pressed together, hand on thigh, elbow tucked in, head slightly bowed, palm of your hand touching your neck.) Wait. Let's be clear that you do the high-power pose in private, before going in front of the audience. Do it in front of real people and they'll call in psychiatric help for you.
Back to Amy Cuddy's experiment.
The results were startling. For the high-power posers testosterone jumped 20% and cortisol dropped 25%. (For the low-power posers it was the opposite - testosterone down 10% and cortisol up 15%.) She also found that the high-power posers became significantly more willing to take risks. Prof. Cuddy was referring to any social risk situation, including presenting.
For presenters it could hardly be more significant. Stand in a powerful pose for just two minutes and your confidence will jump and stress drop. You'll also be more willing to put yourself on the line.
Your body can change your mind
Or more accurately: your mind can tell your body to influence your mind. With a small impulse from your mind to your body (stand in a powerful pose) the body sends a large impulse back to your mind (go ahead and feel confident / in control / courageous / willing to take risks).
As if your body is some kind of amplifier.
Of course it is, there's nothing to lose and everything to gain. Here are another two more power poses.
First: stand, feet apart, leaning forward with hands apart on the table in front of you, as if phyiscally dominating a meeting.
Second: lean back in a chair, hands behind your head, one leg crossed on the other above the knee. And I suggest you throw in a facial expression of supreme confidence.
Want to know more about the research? Here's Prof Amy Cuddy, talking about it.