10 Subtle Tricks Horror Movies Use To Scare You

This one is pretty infamous thanks to some irresponsible advertisers famously attempting to make commercial use of it when first discovered (despite the fact that a lot of its much-debated effectiveness has been largely debunked in the years since its discovery).

Subliminal imagery refers to images featured in films for such brief, one-frame lengths of time that they can't be properly perceived by the viewer. When it was first discovered and discussed as a phenomenon, subliminal messages both visual and auditory were thought to be a sort of dark magic through which filmmakers could code secret messages about the Illuminati and musicians could convince listeners to worship Satan.

However, now that the initial hysteria surrounding subliminal imagery has died down, modern researchers are aware that the average person won't be convinced to "call home" by a subliminal message urging them to do so in single frame of film. What subliminal images can do, though, is terrify viewers when they are slipped in during a feature film's runtime, particularly if they are lingered on for long enough that a canny viewer can actually single them out, as seen in The Exorcist's infamous "Captain Howdy" insert shots.