What’s more frightening than a monster hiding at the end of a dark hallway? Realizing the person closest to you, whom you thought you knew, is not who they seem to be at all.

The genre of horror has been steadily growing in popularity over the past few decades. In 1970, 2% of all feature films were classified as horror. That percentage had increased to 12% by 2016, according to research done by the American Film Market.

Beneath the umbrella of horror, subgenres have emerged such as slasher, paranormal and psychological to name a few. Psychologically-thrilling horror movies are unique in that they rely more on fear of the unknown and mystery than traditional horror gimmicks.

One of the best known examples in psychological thrillers is “Gone Girl” directed by David Fincher in 2014. Before the film went on to gain critical acclaim and dozens of awards, it was a novel written by Gillian Flynn. The story’s central themes include uncertainty, deception and distortion of reality. Psychological thrillers draw on the mind’s fear of the unknown and destruction of trust, and “Gone Girl” is a perfect example of these tactics combining to create a truly unsettling atmosphere.

Audiences become invested in a plotline when they cannot possibly predict what will happen next. The phrase “on the edge of my seat” is an accurate description of how one feels on their first watch of “Gone Girl” because so much information is withheld from the viewer.

According to the National Library of Medicine, our minds are wired as prediction machines. The human brain is biologically aimed toward filling in gaps, but in a story like “Gone Girl,” that is impossible.

This inability to predict what is coming next creates cognitive tension, or suspense. The feeling of suspense is uncomfortable and registers in the brain as danger. Since this danger is not tangible, your mind is forced to work harder to try and find answers. As viewers try to piece together what they know is true and what information is being manipulated, each character becomes a suspect.

Unreliable narrators are a tool used in this genre to create a sense of instability. Audiences build relationships of trust with characters, only for the metaphorical rug to be pulled out from under them at a pivotal plot point. This is not an oversight from the creators of the film, but another tool that uses human psychology to unsettle the viewer even more.

Another psychological fear is introduced: betrayal. According to Impact Psychology Services, the hurt of betrayal is a psychological wound that is unlike any other. In slasher-horror films, the audience tends to view the protagonist as an extension of themselves, because they have the same amount of information and are usually motivated by the desire to survive.

In psychological thrillers, this connection is turned on its head as different motivations are unearthed that further complicate who the audience can and cannot trust. Manipulation, deception and distortion of the truth further the disconnect between the audience and character they once trusted or even saw as the “good guys.” This is shown in “Gone Girl” as the audience slowly realizes they cannot trust the character they may have thought was the victim.

These thrilling depictions of mistrust and betrayal stay with viewers long after watching the film. That is because psychological thrillers rely on possible human behaviors and fears instead of the supernatural or larger than life villains. It is possible for someone you know to be completely different than who they say they are. It is possible for your closest friend to break your trust. It is possible for someone you are in a relationship with to manipulate you.

These are the reasons that the plots of many psychological thrillers stay with their audiences long after the credits roll. “Gone Girl” leaves viewers questioning their own reality as well as trying to figure out how they would react if they were placed in the same circumstances as the main characters. This does not make the film necessarily more scary than other horror movies, rather, a different experience of fear in the same genre.

Creating a good psychological thriller requires a delicate balance of tension, paranoia and suspense. While some films in this category do have more dramatic scenes, most cannot fall back on shocking chase scenes or jumpscares.

This means that instead of a momentary spike in fear when the audience thinks the villain is about to capture the protagonists, the creators must manufacture an environment in which the viewer is questioning who the real villain even is.

“Gone Girl” is only one example of this subgenre of movies, but the list is expansive and includes some of the most critically acclaimed films in history. Movies like “Psycho,” “Silence of the Lambs” and “Get Out” have cemented themselves in cinematic history and are frequently referenced in popular culture.

So, while movies like “Gone Girl” might not have a jumpscare moment where we all throw our popcorn into the air, they can be just as unsettling as some of the best horror movies. During this Halloween season, give psychological thrillers a try, and you might find yourself unable to turn back.