Horror lovers don't need to explain it to one another, horror's awesome. For non-lovers it's perplexing. They don't get it. The violence, the gore, and the scares aren't fun for them and they can't understand how anyone could have a good time at a horror movie. Sometimes curious non-initiates thoughtfully and carefully ask me, "Why do you enjoy horror so much?" Other times the question is less carefully, but no less thoughtfully worded as, "Jesus Christ, how can you watch that crap?"
The truth is, I don't always enjoy horror movies because a lot of what I watch is, in fact, total crap. Usually the crappiness stems from bad writing. Less common is the decent horror script suffering a bad director. In either case, the film isn't scary and I don't get to experience that rush of fear--what academics like to call negative affect.
I've got a big pile of papers that deal with the need for affect, negative affect, and the appeal of same in relation to horror. Summing it up, horror lovers watch horror movies because it allows them to safely explore a powerful emotion they don't feel very often: fear. Fear itself is rather subjective, but a skilled filmmaker knows how to work the medium to his advantage, to scare as many people as possible.
Back in the day, directors relied on things like experience and talent (and good writers) to make their horror movies scary. Today they use science.
The amygdala is a cluster of neuclei nestled deep in the brain. It's part of the limbic system, which handles emotions. In particular, the amygdala is believed to process fear. When we're scared, the amygdala is hard at work, and if we were to watch it in action, we would see it light up.
That's an fMRI (the f stands for functional) capture of a test subject's brain while he/she/it is experiencing fear. This kind of neuroimaging might well be the future of filmmaking--it's already the present of film marketing, having been used by studios cut better trailers. In fact, filmmaker Peter Katz used fMRI to see how his audience reacted to his movie, Pop Skull. He was surprised to learn the more creepy and suspenseful moments generated more of a fear response than the jump scares.
Pop Skull was a finished product when Katz hooked his audience up to the machine, so there was little he could do with the results. But when the Dowdles were making the Poughkeepsie Tapes, they used fMRI help them determine if a particular scene needed re-editing to make it scarier. The directors were keen to use a green filter, believing the colour shift would incite fearful emotions in the audience. The results showed the green filter actually detracted from the scene, reducing its effectiveness.
Although neuroimaging proved useful to filmmakers as a tool to gauge scariness, these two examples also take us into the minds of the directors themselves. What we're seeing here is that some genre filmmakers clearly have no idea how fear works and what scary is. In short, they don't seem to understand horror. It's powerfully ironic, but also kind of sad.
The benefit of neuroimaging is that fMRI might improve future horror projects, as directors slowly learn how to tap into the amygdala and make movies that are truly frightening, but there's a risk that filmmakers (read: studios) will confuse the technology for creativity, replacing one with the other. As was/is the case with 3D, technology can certainly enhance the movie-going experience, but it cannot substitute for story and plot.