Ferchi

For interactive stunts and gimmicks at movie screenings, we all owe a debt of thanks to William Castle, a prolific director of low-budget horror films in the 1950s and early 60s. He used techniques with strange names such as Emergo and Percepto that included floating skeletons above the audience, vibrating seats and ghosts that could only be seen by wearing red-tinted cellophane glasses. His imitators include Smell-O-Vision and having audiences sign medical releases in case they were scared into a heart attack. One Castle film, 1961s Homicidal, included a 45-second onscreen "" before the climax of the film, during which an audience member could leave if they were too scared and even get their money back. In another, the audience could choose the ending with a flash poll.