> The third might be the ability to retain knowledge,

That made me think of a short SF story I read about a year ago, about a man who underwent an experimental surgery that allowed him to have total, perfect recall of everything he had ever experienced. He used his newfound ability to blackmail his superiors, including the two scientists who had performed the operation on him. That's gratitude for you.

Gri"needless to say he got himself into a heap o' trouble"shny