It's fair to say that the overwhelming majority of horror movies - even the really, really good ones - are rollercoaster rides which the audience watches fully in the knowledge that the terrifying sights they're viewing aren't real.
But every so often, an uncommonly effective horror film manages to capture the audience's imagination with its impressive commitment to authenticity, whether the result of a convincing filmmaking style, shockingly believable acting, or a steadfast commitment to a groundbreaking gimmick.
Of course, this list is naturally concerned with found footage and mockumentary horror films above all others, given the ease with which they can pass as real compared to more conventional narrative films.
And though we as active, skeptical audience members might be tough to trick nowadays, over the last 40 years, exceptionally talented filmmakers have found fantastically creative ways to fool even the most level-headed among us.
If movies are often said to be about escapism, these 10 horror classics ventured in the total opposite direction, bringing the terror to your front door and possibly giving you sleepless nights as a result...
10. Lake Mungo
In the decade-plus since its release, Australian mockumentary Lake Mungo has slowly picked up a wealth of cult fandom in horror enthusiast circles.
The directorial debut of Joel Anderson - and sadly still his only movie to date - depicts a family attempting to come to terms with the drowning death of their daughter, Alice Palmer, and the seemingly lingering presence of her ghost in the family home.
Despite being unabashedly supernatural in nature, the film is constructed so smartly by Anderson, using low-fi video sources for the most part, that the eerie ambiguity of the imagery only makes it more plausible to even the rational mind.
Between the shockingly convincing performances of the cast and spot-on docu-style format, Lake Mungo locks viewers in an anxious vice grip all the way to its gut-wrenching conclusion, ending with a haunting closing image which, while objectively a work of fiction, is sure to linger in the mind long after.
Though Anderson didn't embark on any sort of Blair Witch-esque crusade to market the film as a "real" documentary, the technical and psychological plausibility of the piece make it feel real even in its more outlandish moments - and it's all the more chilling as a result.