The horror genre is home to many different tropes that are drawn upon over and over again — the masked and seemingly immortal or indestructible killer, the Final Girl, the jump scare, the unsettling notion that no one is ever really safe from a deadly fate. But there's one element that comes into play more often, whether it occurs early or slowly permeates as a throughline of the plot from beginning to end.
We see it reflected in its most innocent and perhaps well-meaning version when a character (typically the main one) insists that what they've witnessed is true, that a traumatic or gruesome event that has played out in front of their eyes exists in reality, only to have a close friend, a loved one, or a member of local law enforcement insist that they must have just imagined it in the first place. It's usually a response made in an attempt to reassure the lead that nothing bad is going on, but as a story device, it effectively sows doubt within the narrative and renders the audience powerless by extension. We can confirm that nothing is made up here, but there's no way for us to warn someone through the screen about the real threat that could be coming.
Even though these sidekicks, significant others, symbols of law and order mean well enough, they're still inadvertently participating in what has come to be known as "gaslighting" — a broadly pervasive concept in horror used to varying degrees of manipulation, and never more insidious than when it's weaponized against women.
Warning: Spoilers for 2020's The Invisible Man within.
Gaslighting, as a term, comes from the 1938 play Gas Light, which was eventually adapted for the silver screen in the U.K. in 1940 and in the U.S. in 1944, the latter directed by George Cukor and starring Ingrid Bergman. The first film version adheres more closely to the source material, but the second made several changes to the overall plot and character relationships while keeping the story's main conceit — a woman whose husband slowly and methodically destabilizes her on a mental and emotional level with the goal of making her question her own sanity, and ultimately rendering her so incapacitated that he'll be able to institutionalize her and be given power of attorney over her inherited wealth and assets.
Gaslighting plays out to even more terrifying results in horror movies when it occurs within the context of a romantic partnership, but the manner in which it's wielded against female characters adds a more insidious layer to an already unsettling narrative. There's likely no better example of this in older horror cinema than 1968's Rosemary's Baby, adapted from the novel by Ira Levin and starring Mia Farrow as the titular woman who begins to harbor suspicions that her neighbors belong to a Satanic cult and have designs on taking away her unborn baby.
She inevitably gives birth at home, restrained and sedated during labor, only to wake up and be told by her husband and the doctor — himself a close friend of said neighbors — that the baby died. A horrified Rosemary continues to ask where her child is even as the doctor places blame for the loss on her shoulders: "At the hospital, I might have been able to do something about it, but you wouldn't listen." Rosemary insists otherwise, having plenty of evidence to the contrary that her baby is still alive and that the members of the coven have stolen it from her, only to be subdued and sedated again. In the weeks that follow, Rosemary attempts to recover from her trauma while remaining convinced that she can hear her baby crying from another apartment, although her husband Guy contends that it belongs to new tenants who have just moved into the building. Of course, those familiar with the story know what happens by the end — Rosemary's suspicions about her neighbors and how her husband collaborated in offering her womb as a Satanic sacrifice are definitely not unfounded in the slightest, but as she slowly descends into a state of maternal madness, the signs of everyone who contributed to making her question her circumstances are even starker in hindsight.
And gaslighting as a form of psychological manipulation has only persisted over the years in horror cinema, often extending beyond the characters on-screen and outward to us as viewers, causing us to doubt what could be playing out in front of our eyes, too. The 2016 film The Girl on the Train, based on Paula Hawkins' novel of the same name and featuring Emily Blunt, follows an unreliable narrator in the lead character Rachel, who — in part due to her aimlessness and lonely yearning after a divorce and the loss of her job — becomes enamored with the lives of the people she witnesses from her train ride into the city every morning, and later inserts herself into a missing person's investigation when she suspects that there has been foul play in the disappearance of a local woman named Megan (Haley Bennett). But in the same breath, both the book and the film take pains to establish that Rachel is an alcoholic, and therefore anything she thinks she may have witnessed may not be fully trustworthy, especially because she experiences blackouts from too much drinking. In the end, we learn that Rachel's ex-husband Tom (Justin Theroux), who has his own reasons for not wanting Megan's disappearance to be pursued any further, has been planting false memories in Rachel's head during her drinking episodes, twisting the narrative she's constructed about what might have happened in order to turn suspicion away from himself.
When she makes an appointment with a counselor at a local behavioral center, she signs a form that, unbeknownst to her, commits her to a 24-hour stay — which turns into seven days after incidents of violence against a staff member and another patient. Throughout it all, Sawyer insists that she recognizes David working in disguise as an orderly at the facility under the alias of George Shaw, but is repeatedly subdued and sedated for what the staff perceives to be harmful emotional fits. Meanwhile, David's continued and unhindered access to Sawyer in his position of authority (it's later revealed he murdered the real George Shaw and took his place) enables him to continue his manipulation, thereby rendering Sawyer even more helpless — and all as a result of her desire to seek help for something that has rendered her emotionally scarred in the first place.
Where this reimagining absolutely triumphs is in its framing of the story through the eyes of its protagonist, Cecilia Kass, in a quietly powerful performance by Elisabeth Moss. In this version, Cecilia is the emotional center, and the film follows her struggle to prove that her abusive ex-partner, optics engineer Adrian Griffin (Oliver Jackson-Cohen), continues to keep her under his thumb through his most ingenious and insidious invention after staging his own death. Adrian left his wealth to Cecilia, which she has mixed feelings about accepting, but also on the condition that she isn't declared mentally unfit. Of course, given his constant efforts to undermine her mental health and toy with her in ways that gradually evolve to acts of outright violence, how can she prove his existence and convince anyone that she's in her right state of mind — especially when no one can see him? At the film's climax — after Cecilia has been framed for the murder of her sister at Adrian's hands and just learned that her abuser has switched out her birth control in order to get her pregnant, exacting another form of control over her — it's difficult to see how she could possibly free herself from that situation, and the real victory occurs in the manner in which she finally, decisively does.
The dread of The Invisible Man is a creeping sensation, one that happens slowly, progressively and over time — and like Cecilia, we're privy to the same feelings of helplessness, the calculated abuse that escalates further and further until it feels like there might not be any escape. But the techniques that Adrian weaponizes against her are versions of what has played out in the genre throughout decades. The reason that gaslighting has been and continues to be so frighteningly effective is that manipulation isn't rooted in the supernatural; the real horror occurs as a result of what one person is capable of doing to someone else in order to strip away their emotional and mental defenses and leave them at their most vulnerable — and in the end, that might be more terrifying than a killer in a mask could ever hope to be.