That's interesting..
If my current wizard ever dies, I think I'm going to try playing a psychopathic psion. I think I'd be able to give it a decent go.
I suppose I may have been unclear. There's often a lot of surface differences - my roommate has played a raver, a doctor, and now an AVON sales lady who fights zombies. But at the same time, there's deeper similarities in conversational style, use of language, decision-making methods, and personal preferences that mean they all play fairly similarly (in her case, she loses her temper quickly - for some characters this makes them very verbally hostile, while others move quickly to combat)
It does also depend on your audience. Playing a "convincing"...
From Mike Darwn's Chronopause, an essay titled "Would You Like Another Plate of This?", discussing people's attitudes to life:
Conclusion, graphs, and references in article. As usual, I recommend reading Chronopause.com as Darwin has many good articles; to quickly link a few: