Psychological thrillers

• Psychological – Elements that are related to the mind or processes of the mind; they are mental rather than physical in nature. Sometimes the suspense comes from within one solitary character where characters must resolve conflicts with their own minds. Usually, this conflict is an effort to understand something that has happened to them. These conflicts are made more vivid with physical expressions of the conflict in the means of either physical manifestations, or physical torsions of the characters at play.
• Thriller – Generally, thrillers focus on plot over character, and thus emphasize intense, physical action over the character's psyche. Psychological thrillers tend to reverse this formula to a certain degree, emphasizing the characters just as much as, if not more so than, the plot.
• Psychological thriller – Characters are no longer reliant on physical strength to overcome their brutish enemies (which is often the case in typical action-thrillers), but rather are reliant on their mental resources, whether it be by battling wits with a formidable opponent or by battling for equilibrium in the character's own mind. The suspense created by psychological thrillers often comes from two or more characters preying upon one another's minds, either by playing deceptive games with the other or by merely trying to demolish the other's mental state

A good psychological thriller is Shutter Island, the storyline is U.S. marshal Teddy Daniels is assigned to investigate the disappearance of a patient from Boston's Shutter Island Ashecliffe Hospital. He's been pushing for an assignment on the island for personal reasons, but before long he wonders whether he hasn't been brought there as part of a twisted plot by hospital doctors whose radical treatments range from unethical to illegal to downright sinister. Teddy's shrewd investigating skills soon provide a promising lead, but the hospital refuses him access to records he suspects would break the case wide open. As a hurricane cuts off communication with the mainland, more dangerous criminals "escape" in the confusion, and the puzzling, improbable clues multiply, Teddy begins to doubt everything - his memory, his partner, even his own sanity.

This film toys with your mind to the extent of confusion, the twist in the film makes you wonder why everything else happened and how did he make his make believe world seems so real.