…according to a recent article on Forbes.com (3 Nov):
In business, politics and romance, it would be nice to know when we’re being lied to. Unfortunately humans aren’t very good at detecting lies. Our natural tendency is to trust others, and for day-to-day, low-stakes interactions, that makes sense. We save time and energy by taking statements like “I saw that movie” or “I like your haircut” at face value. But while it would be too much work to analyze every interaction for signs of deception, there are times when we really need to know if we’re getting the straight story. Maybe a crucial negotiation depends on knowing the truth, or we’ve been lied to and want to find out if it’s part of a pattern.
The article has ten accompanying slides, with suggestions for the would-be lie catcher. Among the sensible suggestions – like monitoring pauses, seeking detail and asking the person to repeat their story – other slides suggest that gaze aversion, sweating and fidgeting are all signs of deception, despite the fact that there is no scientific evidence for such behaviours being more common in liars than truth-tellers. They also suggest:
Look for dilated pupils and a rise in vocal pitch. Psychologists DePaulo and Morris found that both phenomena were more common in liars than truth-tellers.
Both pupil dilation and pitch changes are indications of changes in arousal level (stress cues), and can often be very subtle. Probably not the best cues for a lie-detector to rely on. The Forbes article concludes:
Psychologists who study deception, though, are quick to warn that there is no foolproof method. […] It’s tough to tell the difference between a liar and an honest person who happens to be under a lot of stress.