The most popular theory on why we like horror is that we get an adrenaline burst during the whole horror movie experience. We like to feel scared knowing that nothing can hurt us. It gives us that burst when a slasher appears out of nowhere, and it's that burst of adrenaline that makes us feel alive. Horror movies are almost like cocaine for the senses.
Psychologists also believe that we enjoy the overwhelming feeling of relief when the horror over and we walk out of the theater. I haven't seen a truly scary movie since I was a kid, so I don't put much faith in this. For me, the horror stays long after the movie is done. So the relief is gradual and it's not as awesome as a feeling as they seem to think it is, and certainly doesn't justify why we watch those movies.
When a man enjoys a horror movie, it's speculated they enjoy them because they place themselves in the movies. Since most horror movies have a male hero (though strong female leads are popping up more frequently) they place themselves in their shoes. In theory, they enjoy horror because they are able to overcome something that is mean, scary, and murderous without having any real danger to their well being. Well, no real danger until one of us mentally ill people light fire to the theater to liven things up...
There's no great psychological theory for why women like horror movies, I think the psychologist who dreamed up the theory for why men like horror may have been a bit sexist like Freud. More than likely, normal girls are taken to those movies by their boyfriends who get a kick out of seeing them frightened. Though the abnormal girls, like myself, probably go because they really like horror.
In his essay, Stephen King discusses that we were trained into what civilization expected of us. Do something good, get a treat, do something bad, get punished. However he theorizes that our "anticivilzation" behaviors like being violent don't go away. We just need to keep them "fed", so to speak. These behaviors are represented by alligators, as long as we feed them with horror they stay locked away.
This makes sense. I've been around quite a few little kids, I was one too not entirely to long ago. Little kids are...kind of mean until taught otherwise. This leads to the theory that we as humans are violent little murder machines programmed to kill. Sort of like Terminators, but not as metallic.
So when we go to see a horror movie, we watch it because deep down we are getting a nice little burst of morbid joy out of seeing people killed. The proof in this can go back to ancient times where people watch gladiators fight to the death. In the American civil war, where people had picnics to watch some of the first bloody battles. The days when people attended public executions because there was no television to thrill them. The proof is all riddled throughout mankind's' bloody history. Most of us won't admit that we enjoy it, most will fervently protest that it's horrible, but next time you find yourself watching a bloody flick think about what you feel. Why are you watching it? What thrills you about it?
Source: http://www.infobarrel.com/Why_We_Watch_Horror_Movies_Especially_The_Bloody_Ones
