Filling in the dark room: perception in horror

When I graduated from college four years ago, I started working in Washington DC. Some of you know where, but since they instilled a healthy love of discretion in me, I won't name them here. But like most government facilities, the building was steeped in history. In the time I worked there, I heard all the stories, the WWII-era legends, the rumors of tragic artifacts supposedly still on-site somewhere. And of course, I heard the ghost stories.

Our facility was a cavernous compound, made up of two buildings. One was sterile, functional, built to hold our various offices and nothing more. The second was older, more ornate; when this particular institution was first built, it was both a residence and a central hub. Now it housed a few departments, but otherwise was used mostly for events. The easiest way to go from one building to the other was to walk through the gardens outside, but the two were also connected through the basement.

The basement under the newer building held the chauffeurs' breakroom, and a hard-to-find ping-pong table, but was otherwise a quiet, unused maze of hallways with dozens of doors that led to nowhere. The basement under the older building was always darker, chillier. It had, at one time, been the home of some staffers, and you could find the closet-sized dorms if you went in deep enough

This is where all the stories were set, of course.

As a staffer, I went down to the basement a handful of times. The first few times, the older staffers served as tour guides. But after a while, a few of us had the confidence to start taking tours of our own. Without a natural leader, there was a bit of hesitance when it came to who should walk down those dark hallways first. And more often than not, it ended up being me.

Being a horror writer doesn't mean the usual tropes won't scare you. The stairways-to-nowhere and the rusty bathtubs always gave me the shivers. But much like Mad-Eye Moody, I'm all about constant vigilance. I've always had an overdeveloped sense of whether I have company or not - and I was always sure, on those basement tours, that I didn't.

The only time I was less-than-sure, I was in that older building, but I was two floors up from the basement, in the kitchen and in broad daylight. I was standing beside two of my friends, listening to instructions, when I felt the friend next to me, S, take a step back toward the cutting boards, covered in veggies for our event. I heard the rustling of the plastic bag covering the tomatoes, I heard someone moving around - everything in my spatial awareness was telling me that S was behind me, preparing the vegetables.

Then I glanced to the side, and S was where she had been the entire time: right next to me.

If you asked me now, my best guess is that the rustling came from a mouse trying to get at the veggies - though I suppose you can guess for yourself. But if it was a rat, what about the other sounds? Did I really feel S take a step back before the rustling started, and did I really hear footsteps? Or did my brain pencil those details in based on what I assumed was happening?

While working on my last project, I texted a brilliant neuroscientist friend for help with a scene, as you do when you are a writer and have amazingly patient friends who don't mind out-of-context questions. She explained the concept of 'filling in': that there is a blind spot on our retinas without photoreceptors where the optic nerve meets the eye, and the brain fills in the missing information based on context clues.

We can't perceive everything at every second, but most people don't spend a lot of time thinking about those gaps. We have ways to compensate. Writing horror means trusting that, and leaving space for it. Fear is personal and specific from person to person. And if someone hears a sound behind them in a dark room, chances are their mind will fill in the thing they want least to be there.

And if your reader can't rely on your main character's perception - or their own - that puts them on unsteady ground. And if they're reading horror, that's exactly where they want to be.

Here's hoping your Halloween isn't too creepy. (Or here's hoping it is, if that's what you're into!)