There are unique individuals who can detect subtle signs that people give away when they lie; these human lie detectors are called the truth wizards. A truth wizard is a person who naturally acts like a lie detector machine but without the aid of the standard polygraph test questions.

This ability to tell whether or not someone is fibbing can be taught and learned, but some truth wizards have no formal training at all. Maureen O'Sullivan at the University of San Francisco made a study which yielded the staggering ratio of 31 inborn truth wizards in 13,000 people. The results of the study strongly benefit the law enforcement sector, because observing how truth wizards work and how they detect deceit can unlock the doors to human behavior and lying.

A stunning precedent to the concepts and rationale behind micro-expressions is the popularity of the Fox television show Lie to Me. The main character on this show was based on Paul Elkman, an expert on body language and facial expressions and a psychologist (also based in the University of San Francisco, same as O'Sullivan). Now, micro-expressions have become a household word.

Micro-expressions are changes in people's facial expression that linger for less than a second, which makes it very hard for normal people to detect. Trained observers or videotapes which are run very slowly can be the only ways to detect micro-expressions.

O'Sullivan has identified two types of lie-detector clues: the thinking clues and the emotional clues. The thinking clues are the lying indicators that slip even in the most accomplished liars because it's much more difficult to tell a lie than to narrate the truth. For people who excel at lying, they overcompensate this by talking too fast. Emotional clues are screened by detecting the micro-second burst of emotion on a person's face or movements.

Moreover, the study also revealed that a good percentage of these so-called truth wizards are good lawyers, possibly because they are very sensitive to the way people use words in their day-to-day profession, and Secret Service agents who provide protection to politicians and scan crowds for nonverbal cues. Intelligence also plays a big role on whether or not the person can acquire the ability of a human lie detector, because the 31 truth wizards who are pinpointed among the 13,000 test subjects possess a high level of intelligence.

Detecting dishonesty in others is a trick that can be learned little by little. Reading on various lying clues and practicing lie detection techniques can help.