October or not, I’ve been a big fan of horror movies for some time. I became hooked in high school when The Ring was in theaters and everyone was abuzz about the video that could kill you in seven days. Ever since, I’ve been hooked on the spooky and supernatural. I’m quite happy watching on my own, but it’s when I try to find someone to watch with me that sometimes I’m surprised. I can never quite predict which of my friends will be willing to join me, and some people are shocked to find out that I enjoy haunted houses and monsters.

Why do some people love horror movies, some people stay far clear from them, and some people remain relatively indifferent? A lot comes down to science.

I found this when searching images for "fear." These creatures are in fact a very specific fear of mine, and I'm slightly disturbed that they appeared. Image by Tor Lindstrand.

The physiological fear response is one of our most primal drives. Fear unleashes an immediate flood of adrenaline and other hormones into our bodies that prepares us to fight or flee. Senses are heightened, our quick breathing gives more oxygen and power to our muscles, and time can even seem to slow down. While our subconscious “lizard brain” is preparing to save our lives, our conscious thinking brain is also powering up, assessing survival tactics and severity of threat. It can be this interplay between conscious and subconscious that makes horror enjoyable.

If someone scares you in a haunted house but your conscious brain is able to understand that you aren’t in real danger, you may experience the adrenaline rush as pleasurable rather than paralyzing. Fear becomes translated into excitement, causing many people to burst into laughter after being startled by a costumed ghoul. I can see this interplay directly at work in my horror film preferences. I steer towards ghost films and monster attacks rather than slasher flicks. It’s much easier to convince myself that I won’t be attacked by a xenomorph than that I’ll never be hurt by a fellow human. Harnessing the fear response for pleasure is quite likely why people are drawn to extreme sports like skydiving or mountain climbing too.

There’s another aspect of fear that is associated with pleasure: Dopamine. Dopamine is released during fear episodes, but usually dopamine is associated with reward and feeling good. It may be that the brain releases dopamine during fear to reward itself for responding to a threat. There are a number of fear disorders, like paranoia, associated with elevated levels of dopamine in the brain. Could paranoia be aggravated by the brain becoming addicted to feeling fear? Perhaps. When people go to a haunted house, they might enjoy the adrenaline rush, but they also might be cruising on a dopamine high afterwards too.

This explains why many people enjoy horror movies, but not why some people don’t. The difference between horror lovers and horror avoiders might come down to another aspect of brain biology. Hormones like dopamine and adrenaline are registered by molecules called autoreceptors on nerve cells. They monitor the level of hormones and chemicals in our bodies and can help regulate levels of these chemicals.

When scientists compared the levels of autoreceptors between people who enjoy a good scare and those who don’t, they found that the people who were less fear-seeking had fewer autoreceptors. Brains with few autoreceptors take less hormones to provoke a response than those with many, meaning that a scary movie is much more likely to oversaturate them with fear hormones and cause discomfort.

So liking horror movies or not isn’t a reflection of character, it might just be brains wired a slightly different way. All is not lost even for those who have few autoreceptors, though. If someone is exposed repeatedly to something they find scary, their brain eventually starts to get used to it and find it less frightening. Many treatments for anxiety and phobia disorders work off this principle, that repeated safe encounters with a frightening stimulus can eventually lead to a greater level of tolerance.

Unfortunately for thrill seekers, the same holds true for them. Something that may have once been frightening in an exciting sort of way, like a favorite horror movie first encountered in high school, may now inspire little response. Well, even if I’m no longer afraid of the Ring, at least I’ll always have American Werewolf in London… at least until my brain desensitizes itself to howls and snapping teeth too.

- Kate Dzikiewicz, Paul Griswold Howes Fellow

Want more fear science? Read about the evolution of fear here. Want something not to be afraid of? Consider liking bats more!