Deception Detection: Science News Online — Good article for those who think they can spot a liar.

The extra effort needed to remember what they’ve already said and to keep their stories consistent may cause liars to restrain their movements and fill their speech with pauses. People shading the truth tend to make fewer speech errors than truth tellers do, and they rarely backtrack to fill in forgotten or incorrect details.

“Their stories are too good to be true,” says Bella DePaulo of the University of California, Santa Barbara, who has written several reviews of the field of deception research.

Liars may also feel fear and guilt or delight at fooling people. Such emotions can trigger a change in facial expression so brief that most observers never notice