Gaslighting

# Overview
Gaslighting is a form of psychological abuse in which false information is presented with the intent of making a victim doubt his or her own memory and perception. It may simply be the denial by an abuser that previous abusive incidents ever occurred, or it could be the staging of bizarre events by the abuser with the intention of disorienting the victim.
The term "gaslighting" comes from the play Gas Light and its film adaptations. In those works a character uses a variety of tricks to convince his spouse that she is crazy, so that she won't be believed when she reports strange things that are genuinely occurring, including the dimming of the gas lamps in the house (which happens when her husband turns on the normally unused gas lamps in the attic to conduct clandestine activities there). Since then, it has become a colloquial expression that is now also used in clinical and research literature.

# Etymology
The term derives from the 1938 stage play Gas Light (originally known as Angel Street in the United States), and the 1940 and 1944 film adaptations. The plot concerns a husband who attempts to convince his wife and others that she is insane by manipulating small elements of their environment, and insisting that she is mistaken or misremembering when she points out these changes. The title stems from the husband's subtle dimming of the house's gas lights, which she accurately notices and which the husband insists she's imagining.
The term "gaslighting" has been used colloquially since at least the late 1970s to describe efforts to manipulate someone's sense of reality. In a 1980 book on child sex abuse, Florence Rush summarized George Cukor's 1944 film version of Gas Light, and writes, "even today the word  is used to describe an attempt to destroy another's perception of reality".

# Introjection
In an influential article "Some Clinical Consequences of Introjection: Gaslighting", the authors argue that gaslighting involves the projection and introjection of psychic conflicts from the perpetrator to the victim: 'this imposition is based on a very special kind of "transfer"...of painful and potentially painful mental conflicts'.
They explore a variety of reasons why the victims may have 'a tendency to incorporate and assimilate what others externalize and project onto them', and conclude that gaslighting can be 'a very complex, highly structured configuration which encompasses contributions from many elements of the psychic apparatus'.

# Resisting
With respect to women in particular, Hilde Lindemann argued that "in gaslighting cases...ability to resist depends on her ability to trust her own judgements." Establishing "counterstories" to that of the gaslighter may help the victim re-acquire or even for the first time "acquire ordinary levels of free agency".

# Clinical examples
Psychologist Martha Stout states that psychopaths frequently use gaslighting tactics. Psychopaths consistently transgress social mores, break laws, and exploit others, but are also typically charming and convincing liars who consistently deny wrongdoing. Thus, some who have been victimized by sociopaths may doubt their perceptions. Jacobson and Gottman report that some physically abusive spouses may gaslight their partners, even flatly denying that they have used violence.
Psychologists Gertrude Gass and William C. Nichols use the term "gaslighting" to describe a dynamic observed in some cases of marital infidelity: "Therapists may contribute to the victim's distress through mislabeling the women's reactions.  The gaslighting behaviors of the husband provide a recipe for the so-called 'nervous breakdown' for some women  suicide in some of the worst situations."