Candidates' body language

When 50 million or so Americans settle on their sofas to watch the final presidential debate, they'll undoubtedly be looking for a moment of authenticity. A moment that, despite the polished messages and the hours of preparation, reveals a candidate's true character. Body language experts call it "the tell." An unguarded retort, an angry finger jab, or an impatient sigh that--just like in poker--can provide some crucial insight.

Here, a half-dozen body-language and speech experts weigh in on the debates, pointing out patterns and offering advice on how to decode tonight's big political dance.