People seem to depend on body language to determine truth, instead of actual thinking about evidence.
New York University and the University of California, Berkeley have released a comprehensive computerized study of the body language of the major-party U.S. presidential candidates, using expertise of computer scientists and body language experts at both universities.
... matched the words with the gestures of President Barack Obama and Republican nominee Mitt Romney on a word-by- word basis to reveal how much weight or emphasis they put behind specific words. This study highlights what words each presidential candidate emphasized through digital motion-tracking of their body language.
"Physical motions of speakers determine how voters feel about them. How they move influences whether you believe they are standing behind what they are saying -- or if you get the impression they are simply repeating a memorized list of terms. A speaker's physical movements -- arms, legs, shoulders, and facial expression -- can undermine or even contradict the verbal message."
They ... assigned a "gesture weight" to each word the candidates uttered. "Gesture weight" is a calculation of how forcefully the speaker performs a particular gesture. [emphasis mine]
At least for Mitt Romney - he lies when ever he speaks, so it's easy to tell when he's lying.
I read that when a speaker looks up to the right they are activating memory indicating truth telling. Looking down to the left indicates a lie. I don't remember which part of the memory looking left and down are tied to.