In pictures: US candidates' body language

So who has been the most honest candidate, in terms of body language?

Ms Wood says it was former New York Mayor Rudy Giuliani, who dropped out of the race last month.

When a person experiences emotion, it is revealed through their body language before they express it in words, she says.

"Watching Rudy Giuliani you noticed his gestures always came before his words. That showed his statements were credible."