So what does credible body language look like?  With non-verbal communication, it’s always the whole picture that matters.  People read you unconsciously for the most part, and form an impression – an idea of your intent – which only becomes conscious if there’s something really unusual going on. 

That said, there are a couple of areas that are particularly important.  It’s possible that if you creep out on stage, hunched over, not making eye contact, with your arms protectively folded across your stomach, that you could ultimately establish credibility with the audience – but it would be very difficult.  You’d have to work extremely hard. 

Instead, stand tall and straight, head held high, like a soldier, but without the tension in your shoulders.  Keep a little tension in your stomach and lower back, so that your lower back is rolled forward and your tummy tucked in.  Keep a still ‘core’ – that is, your solar plexus area should be still and focused on the audience.  But leave some looseness in your shoulder and arms, so that your gestures can look relaxed and fluid. 

Plant your feet when you deliver a point.  One of the most common unconscious ways people give up credibility is by wandering around because of the adrenaline in their systems – what we call ‘happy feet’ in the business.  Oddly enough, it is often difficult to persuade speakers that they in fact have happy feet.  You almost always have to show them the footage, and then they say, ‘Omigod, you’re right!  I wander all over the stage!’  That’s because it’s unconscious behavior.  Motion that’s purposeful – going from point A to point B to deliver a thought – is inherently interesting.  Motion that’s random is not.  And it’s not credible. 

Of course, closed gestures can undercut credibility, because the audience is expecting you to be an authority with confidence, and closed gestures look defensive and not very confident. 

The other area that’s most important for credibility is your voice.  People often overlook this essential part of ‘body language’.  If your voice constantly goes up in a questioning tone, even when you’re making a statement – as many people’s does these days – then you’re not being credible.  Your voice should rise in pitch to show emotion, and come down to show credibility.  The only exception is when you’re asking real questions.