Dr。 Cal Lightmanis a psychologist with an expertise in body languageand especially microexpressions, and founder of The Lightman Group, a private company that operates as an independent contractor to assist investigations of local and federal law enforcement through applied psychology。
   Though often confronted by people's skepticism, Lightman uses any psychological technique he deems necessary to reach the truth, however elaborate or truculent。
   He is divorced, and has split custody of his teenage daughter。 He cares deeply about Gillian Foster, and there is a chemistry between them that has yet to develop into anything more。
   His mothercommitted suicidewhile he was still young, an event that led him to discovering and researching microexpressions。
   This character is based on Dr。 Paul Ekman; notable psychologist and expert on body languageand facial expressions at UC San Francisco。
   He is also a vegetarian。 There is evidencehe was involves in the Irish National Liberation Army, due to the fact that Reynolds has said "Yeah, I read your file too。
   Northern Ireland? Let's talk about that。。。some of the crap you were involved in Dr。 Gillian Foster, Dr。 Lightman's colleague and co-worker in The Lightman Group。
   Her husband's lack of candor often challenges her open pact with Lightman: not to let their professional skill interfere with coworker's personal lives。
   So, when Cal believes her husband Alec is cheating on her, he simply ignores what he is seeing, much to Torres' dismay。 Gillian had adopted a baby (Sophie) who was eventually returned to the birth mother。
   This character is based on Prof Maureen O’Sullivan, a psychology professor at the University of San Francisco。 Eli Loker, initially an employee of The Lightman Group。
   Loker is academically educated and acquired his skills in "reading" people through practice。 He also adheres to radical honesty, and thus rarely lies, even if that makes him appear rude or undiplomatic。
  [11] Such as in the pilot, when he first meets Torres, he bluntly tells her that he wants to have sex with her。 Lightman demoted him to an unpaid intern after, despite Foster's warnings, he divulged sensitive information to the SEC while working on a case, calling his actions, which includes the fact that Loker made Torres lie about knowingit, "disrespectible, selfish, and just plain stupid。
  " Monica Raymundas Ria Torres, an employee of The Lightman Group, and a protegee of Dr。 Lightman's, who was recognized as a "natural" while she was still working as a TSA agent。
   Torres was abused as a child, a common pattern among naturals, by her father。 Though talented and loyal, she lacks academic training and sometimes lets her emotions cloud her judgment。
   Emily Lightman, Cal Lightman's teenage daughter。 She is under shared custody between her parents, and though she does not appreciate her father's ability to "read" her, she does not deny its merit for social screening。
   She sometimes shows a talent for "reading" people, even her father。 (Recurring Season 1, Regular Season 2) Mekhi Phifer as Ben Reynolds, a FBI agent who assists the Lightman Group in their investigations, offering armed assistance and practical insights。
   (Recurring Season 1, Regular Season 2) Zoe Landau, Cal Lightman's ex-wife。 She is an assistant to the Attorney General and though currently engaged to another man, she also engaged in a tryst with Lightman, after he helped her in a case。
   It was revealed in "Truth or Consequences" that she is half-white and half-African American。 Sean Patrick Thomas as Karl Dupree, a Secret Serviceagent who becomes romantically involved with Torres。
   He was seriously injured during a terrorist attack。 Tim Guinee as Alec Foster, Gillian Foster's ex-husband。 He works at the United States Department of State and is a recovering cocaine addict where throughout the series it was heavily hinted that he was having an extramarital affair until it revealed the woman was his drug sponsor。
   He and Gillian have decided to divorce。