This document summarizes key elements of psychological horror movies. It discusses the plots of three films: Shutter Island, Jacob's Ladder, and American Psycho. It then lists conventions of the psychological horror subgenre, including a focus on exposing the evil behind normal characters, using flashbacks to show what disturbed the characters, having protagonists/antagonists who are mentally ill, including a scene where the mental reality is shockingly revealed, and initially presenting protagonists as normal to create familiarity.