Viewers watch horror movies because they love a good fright. But who's watching the watchers of horror movies? Scientists and researchers, that's who, and they're doing so because horror movies are a ripe field for those who want to learn more about the physiological and psychological responses to fear.
Or maybe they just want to rewatch Jigsaw get a saw in his throat, because that never gets old.
For the second of our 31 posts celebrating the 31 days of Halloween, take a look at what science has learned from horror movies.