Some good posts here, particularly from
@Randy M. and
@paranoid marvin.
It might be useful to return this to the OP, and particularly the essay. I'm assuming most haven't read it, but it is worth a read - it's not very long as academic essays go, and it's mercifully free of any overly academic language; it's an easy read, mostly taken up with reports of the correspondents who filled nin the author's survey.
I found myself agreeing with the idea that I have a greater memory of watching so-called "forbidden" films when I was young - let's say at the age of 11, or 12 - at home, on VHS, than many other films. I remember watching
John Carpenter's The Thing (check out this month's podcast!!) and getting as far as the scene with the dog in the cage, and having to switch off. It took me a couple of years to complete watching the film. The same with
Alien - I got as far as the egg scene and had to stop.
But later in life I've got greater fondness for these films than a great many others I probably watched around that time (there are other non-horrors that I have a vivid memory and love for, like
Who Framed Roger Rabbit? but even that's got some pretty scary scenes for a kid). I didn't watch
the Exorcist until I was older, and I think that film is arguably more frightening for adults, and particularly parents, than children.
There's an element of chasing the dragon with horror - this idea that when you experience the visceral thrill of fear (or perhaps vanquished fear is more accurate?) you want to experience that high again but need something that's at least equal in power to the thing that preceded it. Without going in the direction of ugliness like exploitation films (or even snuff films - the
Inside No. 9 episode about the snuff film is truly terrifying) that's hard to achieve. Certainly the only film that's disturbed me in recent years is
Hereditary.