The creation of fear in a videogame is an inexact science but there's evidence to suggest a neurological mechanism can influence it in some important ways. Writing for Gamasutra, Maral Tajerian, a neuroscientist at Thwackel Consulting, explains the role mirror neurons play in connecting players to their onscreen avatars in horror games.
Mirror neurons are neurons in certain regions of the brain that are active when an animal performs an action, or observes another individual performing that same action.
Discovered a few decades ago, these neurons are argued to be the key in understanding other individuals' intentions and feelings, empathy, and even imitating the actions of others. It is very possible that mirror neurons play an important role interfacing our experiences with a virtual avatar.
In most video games, moving in a three dimensional space is likely to trigger spatial orientation mirror neurons. In the Silent Hill series, similar mechanisms would elicit anxiety and disgust when players are given the choice to stick their hand into a hole in a wall or to take something out of a toilet.
Similarly the same can be said in Dead Space 2, where players are given the choice to crawl in very confined spaces (where the right camera angle make the entire difference) or guide a needle into the eye of Isaac Clarke.
And what's best is that the developers of these games are increasingly aware of these facts and capitalize on it. As Thomas Grip of Frictional Games (Amnesia: The Dark Descent) himself said at the Games Colloquium at Concordia University last year, the involvement of mirror neurons is important when the empathy factor is high. In other words, you can't help but put yourself in the protagonist's shoes.
Everything that a person experiences is, of course, underpinned by some neurological process, but it's especially interesting to note just how much emotion can be wrung from manipulating spatial awareness. Games are just as much about moving through invented places as they are about performing specific actions and scoring points.