Is your boss droning on? Be careful where you look, because darting eyes are a dead giveaway that you're bored. And, as John Walsh discovers, that's not the only body language that can get us – and the stars – into trouble.
What is it with Ed Milliband's compulsive head-nodding? Why do Simon Cowell's eyes flicker when he's being rude to an X Factor contestant? Why do we feel unamused by Ricky Gervais's open-mouthed non-laugh? Is it significant that both Margaret Thatcher and Anne Widdecombe used to close their eyes when answering questions?
The answers are simple. They're all examples of social leakage. Whatever is being said, the body language of these public figures says something else. Ed is begging for someone - anyone - to agree with him. Simon doesn't mean a word he's saying. Ricky is trying to summon an atmosphere of factitious hilarity, without actually saying anything funny. And Margaret and Anne, however calm their replies, were trying to shut out their pesky interrogators, as if they didn't exist.
I've become an expert in this field after studying Body Language: How to Know What's Really Being Said by James Borg, an author of inspirational works who introduces London's advertising and financial executives to the black arts of interpersonal skills. In seven chapters, he takes the reader through the shocking ways our bodies reveal boredom, dislike, anxiety, indifference, mendacity - and, in happier moments, liking and even attraction - and shows how you can control your own gestures and mannerisms to make life less fraught.
He begins with the 1950s report of an LA professor, that when people meet, 55 per cent of their communication is by body language, 38 per cent is by their voice and only seven per cent the words they use. "The proportions would be different if you and this person talked for an hour," says Borg, "But the first three minutes is when they decide whether to stick around with you, or take their drink and leave."