The scary part is never created by the monsters or the events. It's all audio and visual cues, and making a science of creating an unsettling atmosphere where anything would make you poop your pants and throw off your headphones.
If you were walking down a long hallway in the same general atmosphere as Amnesia and then a goofy looking jack-in-a-box thing walked at you, you'd probably be no less scared than if it was one of those grunt things. Amnesia was really good at making a scary environment, not scaring you with events. Jumpscares aren't really scary by themselves, they have to be in the right context. Otherwise, the most they'll do is make you go "woah didn't expect that lol", and maybe startle you for a second.
So on the subject line, most likely the latter, but probably a bit of the former as well. It's probably mostly just that you're not letting yourself get engaged enough so the horror gets to you, which is a fair enough mental strategy.
