How do you know when someone is a liar? Shifty eyes? Growing nose? Pants on fire? Science News surveys several laboratory studies on the nonverbal cues of deception and why some people are so good at spotting fibbers.
"In a now-famous study from more than a decade ago, about 500 Secret Service agents, federal polygraphers, and judges watched 10 1-minute video clips of female nurses describing the pleasant nature films they were supposedly watching as they spoke. Half the women were instead watching what Ekman calls "terribly gruesome" medical films. The legal-system professionals were asked to determine the truth by reading the women's faces, speech, and voices… Most of the observers uncovered lies at only about the level of chance. One group, however, outperformed the others. The Secret Service group had a better-than-chance distribution, with nearly one-third of the agents getting 8 out of 10 determinations correct, the San Francisco psychologists reported in 1991."