According to Arianne Cohen and Lindsy Van Gelder of Real Simple, people who are lying exhibit certain characteristic changes in their behavior, such as altered voice inflections, disassociation with their self-narrative and excessive fidgeting. Liars may also seem overprepared with answers to difficult questions and are known to profess their dedication to honesty more often than is necessary.
Heather Hatfield of WebMD explains that liars commonly use too many details when recounting a story, which serves as an indicator that they have rehearsed their story several times to make it sound believable. It may be possible to catch someone in a lie by asking the person several complicated questions that dig into areas of the story that the individual wasn't prepared to answer. Eventually, a liar may be forced to expose inconsistencies in an account of circumstances, notes Hatfield. It is difficult for liars to fake true emotion while recounting a version of events that never occurred, so mistimed smiles, frowns or laughter can serve as a giveaway that a person is being dishonest. In the same respect, liars often demonstrate rapid split-second displays of the actual emotions they are feeling. It is difficult for most people to see, but Hatfield explains that there are training techniques available to make the facial expressions easier to recognize.