I talked about how cheesy-looking gore can trigger a gut reaction of revulsion, but maybe sometimes the audience needs to do some work to appreciate a scary movie. A friend of mine told me that she went to see Paranormal Activity with a few friends and laughed out loud for the duration of the film. When I watched it in my apartment I nearly shit my pants. Am I really that much of a weenie? I ended up watching it again with friends, including this aforementioned friend, and realized that the two of us had very different viewing methods, the main difference being that I watched the movie. She would glance around the room, look at her phone every few minutes, strike up conversations with people. No wonder she wasn't scared - she wasn't absorbed (though my weenieness is still up for debate).
When you only glance at the screen for a little while before getting sucked back into reality, you’re unconsciously assuring yourself that what’s on the screen isn’t real. And when you have that disbelief, you won't be very thrilled. Maybe you can get through something like Harold and Kumar Go to White Castle that way, but little else.
Suspension of disbelief is a fancy way of saying that in order for anything that deals with the fantastic to entertain you, you need to trash your notions of reality and accept anything the film throws at you. This is a major part of what makes horror movies effective and absorptive, but its up to the audience to willingly forget about reality. What's great about mockumentary horror (or POV horror) movies like Paranormal Activity is that they are designed to make suspending disbelief feel natural.
They feature no-name actors
When we can’t tie a name to the face it makes it easier for us to view them as real people. It’s just more difficult to picture Shia LaBeouf and Megan Fox legitimately being haunted by demons. When The Blair Witch Project was released, it was marketed as an actual documentary with real people, and that uncertainty made it all the more thrilling. At this point we know better, but even with the knowledge that it was a hoax, it still works.
Nothing scarier than nothing
Again, the men and women behind The Blair Witch Project realized this. What’s genuinely scary is subjective: when we can’t see the beast that’s antagonizing our heroes, we can picture it to be as creepy as we can possibly imagine. And, when considering the budget these films typically have, its much better to have nothing on film than a monster that looks like a Garbage Pail Kid reject.
Letting the audience let their guard down
This tactic isn’t exclusive to mockumentaries, but it’s definitely worth mentioning since it's put to use with the daytime/nighttime shifts in Paranormal Activity and The Blair Witch Project. In my opinion, though, no film pulled this off better than REC, a Spanish horror mock-doc about a late-night TV crew who become quarantined in an apartment complex infested with rabid residents. You spend ninety-five percent of this movie thinking “Rabies, I get the picture. This isn’t so scary,” and then, once you feel safe and secure, BAM! The scariness factor is amped up nine levels. Pretty sneaky - and definitely effective.