At the end of "On the Bridge," Seth realizes that Adam is lying about why he didn't intervene in the fight to help Seth. The revelation casts a new light on Adam's earlier boastfulness, and it is clear that Adam lies out of habit. The chronic behavior of compulsive or habitual lying is known as pathological lying.
While many people may tell harmless lies in daily social interactions, such as white lies designed to protect another's feelings or avoid conflict, pathological liars tell lies frequently and often for no particular reason. There is no scientifically agreed-upon explanation for pathological lying, but certain evidence suggests pathological lying may result from central nervous system issues, trauma, head injuries, abnormal cortisol levels, or antisocial personality disorder.
A 2016 study on how the brain adapts to dishonesty identified a biological mechanism that makes lies easier to tell with habit. This "slippery slope" mechanism suggests that many smaller instances of dishonesty can lead to greater transgression of the social codes that determine truthfulness. The same study's findings indicate that dishonesty often arises out of self-interest.
Experts have identified that pathological lies often have no logical benefit to the teller, feature dramatic and complicated details, and portray the teller as a victim or hero. Pathological liars may even believe their own lies, forgetting that the story they are telling was something they invented.
In an extreme example of pathological lying, the serial imposter Frédéric Bourdin began as a child to assume the identities of missing people. Dubbed "The Chameleon" by the press, Bourdin in 1997 told a family in Texas that he was their missing son. Despite having a different eye color and French accent, Bourdin fooled the family for nearly five months, during which time he lived in their house and pretended to be their son. Among several other high-profile impersonations, Bourdin claims to have assumed the identities of over five hundred people.
