Obviously I've been in a sort of transhumanism mindset lately, partially thanks to R. Scott Bakker, partially thanks to Verner Vinge. One of the most interesting elements dealt with by the posthuman is the connection between the substrate of thought and thought itself. I promise, this is leading somewhere fruitful (namely, roleplaying games, perhaps games in general, and the theory thereof). A quick demonstration will clarify any misconceptions about this, namely: A human being thinks in a certain way because of the structure of their thinking organs (brain), while a machine, say, would have to think in a markedly different way due to the differences in construction. This may not be a truism, but its an interesting thought experiment, and one I'm inclined to give credence to for the time being.
The question then is this: When you play a roleplaying game, what is the nature of the interface between the player and the player character. Obviously, the player character is a creation of the player. That doesn't necessarily mean, however, that the interface is automatic, smooth, or even pleasant.
In my experience, playing a character should be akin to wearing a second skin. You want the point of interface between your actual personality and the personality of the character to be smooth and easy. This causes bleedback, of course, making you think and act something more like the version of yourself you've been playing for the last however many hours. I found this most notable when playing patently awful people. It's easy, once you allow your mind to travel down certain paths, to get stuck in them as a rut. Easily aggravated characters can make their players easily aggravated if enough distance is not kept, if the interface is not sufficiently gritty and well defined.
The question comes as to how much "like yourself" your character should be. Obviously, the more you-like, the easier the transition to playing the character. You'll have to abstract less, simply knowing the way the character would behave without thinking overhard on what they would do in any given situation. The less like yourself your character is, the more you'll have to rationalize alternative motives, modes, and ways of thought, slowing down your playing ability and capsizing your immersion in the game.
There's something to be said for stepping out of your comfort zone when playing a character in a game. Hell, that's what most of the games are about! Jocelyn said the other day to me, "I would never go into a dungeon. That's something all of my characters would do."
The key here seems to be a personal balancing act; at what point does the STRANGENESS or ALIENNESS of the character begin to stymie immersion and functionality? Of course, in some games the very point is to immerse yourself in a strange or alien setting. And in all cases, the more you play, the less strange and alien it becomes, until the interface is smooth.
That, it seems to me, is one of the chiefest reasons roleplaying guides include short stories in them. Now, I have, for the longest time, despised short stories in roleplaying supplements. Most of them are shoddily written and I always assumed they were simply present to pad the page count. But the fact of the matter is, not everyone can get the same level of useful information from a "THIS IS HOW PEOPLE BEHAVE" section of a setting book as they can from a short story. Further, the short stories are often integrated into core rulebooks that can lack setting material altogether, or be skimpy when it comes to details. So these short stories are actually serving to make the interface between player and character smoother and easier. The same goes for certain group watching events: before you play Gangbusters, it can get the grit out of the that interface to watch Boardwalk Empire, for example.
The long and short of it is that I'm going to try to be more sensitive to the "interface problem" when composing roleplaying material in the future. I've always approached the guides as an anthropologist would. Perhaps there is more of a benefit to approaching it as an author instead.