There are some "Extra Punctuation" texts about horror in games in case you don't know them already. They're from the guy who does the Zero Punctuation video series on the Escapist. (Which btw includes a very funny review of Amnesia ^^) They're not really "scientific" material, they mostly reflect the personal opinion of the author, but I found them quite interesting to read nonetheless.
Wait - is it allowed to post links here? I hope it is...
The Common Mistakes of Horror Games
Big Studios Can't Produce Good Horror Games
Sanity Meters
Survival Horror on a Cruise Ship
Silent Hill: Shattered Memories
On topic, I've just started playing Call of Cthulhu: Dark Corners of the Earth as well. I quite like it, but it's not very scary yet (and it keeps crashing every 10 minutes -.-)... but we'll see. Amnesia started pretty peaceful as well