One of the perennial topics of debate about role-playing games is the relationship between our character's behaviour and our own real-life personality. This is most commonly framed in terms of the bad acts our characters carry out, such as mass slaughter of enemies in battlegrounds. By any real world standards, these acts are evil, yet most roleplayers wouldn't decide that the player behind the character is also evil. We see it as acting, not a reflection of our true selves, so we can easily refrain from doing those things in real life.
Things get a little more tricky when you're dealing with our character's admirable traits, such as cleverness, courage or confidence. A skilled performer can feign these just as well as they can play the role of a villain, even though they don't possess these attributes in real life. In other words, Gabriel's theory could just as easily be seen as:
The interesting question then becomes: "if we can act out these positive roles in-game, why can't we do the same in our own lives?". Why can't I take on the role of my smooth-talking troll merchant outside the game and make some money?
It seems to me that, as with the question of acting out evil characters, the key difference is one of context. Many years ago, in a late-night whiskey-fueled discussion, a philosopher friend of mine challenged the whole notion of people having a personality. His argument (insofar as I can remember it, given the blurring effects of the booze), was that what people see as being characteristics of an individual are in fact the result of a complex interaction between that person and society. They do some things and get positive feedback, so do more of them. They do others and get negative responses and so do them less. If they had been in a different environment, their behaviour may have been completely different.
In other words, we act differently in-game because others around us are also acting differently. It's up to us whether we meet Mr Dickwad or Mr Darcy.
Thanks to Pilf of /moar alts for the inspiration for this post.