Revulsion. Horror. Terror.
In his nonfiction genre overview Danse Macabre, Stephen King identified these as the three levels of emotion that horror fiction strives for, and I have yet to find a more succinct, or accurate, summation. King also stated that of the three, terror is the finest and purest, but that he’d settle for either of the other two in his work. That seems appropriate…but only because of his implicit acknowledgement that an author should generally try for terror. Much of modern horror, especially in films, seems happy to settle for revulsion.
But, I’m not really looking to go down that critical road here. Let’s focus on those first three words for a moment. Revulsion, horror, terror. Those are powerful emotions, and they play on a lot of different nerve endings. Revulsion is a physical reaction mostly, stomachs and muscles in revolt. Not a bad reaction, but since it’s rooted in the physical, it’s mostly limited to the physical. The body adjusts, compensates, and the feeling passes. It’s a “boo!” moment of the soul, and is fleeting.
Horror is much stronger; it can be thought of as revulsion of the soul. The mind and body recoil in recognition of a bad situation, a more complex reaction that involves the consciousness. It involves the character or characters understanding that something is happening above and beyond whatever Grand Guignol scenario is presented. Horror is usually achieved when a character finds something or experiences something bad (to put it mildly) and reacts. Finding a werewolf on the moors could be considered horror.
Terror, on the other hand, can show up in a couple of different guises. It can come when a character realizes the full extent of the danger that faces him or her. If horror is finding a werewolf on the moors, terror would be being stalked by a werewolf on the moors and realizing you don’t know where it is. If you had to create an equation to define terror, you’d need to combine knowledge of a threat, uncertainty of its abilities and/or location, and inability to adequately address the threat. Terror requires, at some level, the recognition of mortality, which may be why horror movies rarely address terror; the core audience, teens, doesn’t yet believe in that.
In writing, which of the three emotions you aim for will depend on the story you want to tell. There’s nothing wrong with revulsion by itself; it can be a useful tool. As a goal, though, revulsion can be underwhelming, partly because much of its power depends on what its audience is willing to accept. Movies provide a good example of this; what was considered gory and disgusting 20 years ago is passé today. Hell, your average CSI: Wherever episode has more gore than many R-rated films of my youth. Aiming for revulsion ages quickly.
Horror has better legs, simply because it’s a more universal experience; we’re all afraid of something, and most of us have had encounters with those objects of fear that generated feelings of horror. Most of the genre tropes we all know and love are concerned with horror, and that’s fine, because it still works. Any boogedy thing hiding under the bed or haunting the dark generally falls under horror—just about anything Stephen King wrote prior to 1990 or so fits here—unless the author is of uncommon skill or is very careful how those tropes are used.
Terror is the toughest of the three to reach; since it’s a more personal reaction, it requires a greater grasp of character, plot and mood to generate that feeling in the reader. Plus, because it requires that sense of personal mortality and/or danger, it is much more internally focused, so having external factors (like the thing under the bed) can detract from the experience. In my experience, authors like Shirley Jackson were most successful in swinging for those fences: her book The Haunting of Hill House is a disquieting read, and generates terror quite well, in large part because Jackson understood that the reader is far more capable of generating terror in themselves than even the most richly descriptive author. Of course, Jackson’s skill as a writer was no small contributor; read just the first and last paragraphs of the book, and you’ll see what I mean.
If, like any red-blooded trafficker in fear, you really want to scare your audience, understanding these three levels of fear—and knowing which level you want to work at—is a necessary step in deciding how much jugular you want to go for. That’s no guarantee that you’ll get there, but it’s a hell of a lot easier to get where you’re going if you at least know what roads you need to take.