I believe it's not only about talking to oneself. At least, I think many people talk to themselves if not aloud then in one's mind ;) "Split personality" is when one can not decipher that he lives two different lives, though it's absolutely clear to others, IMHO :)

Мышка-Машка, well, of course, it's an illness, but people are strange beings...

it is a very serious problem. it is very dangerous, i guess. i wonder why some people can be subject to this illness and some not.

Kim_Berly, it may be dangerous and may be not. And you never know if it is so. So THAT is dangerous. I just have seen so many films about it that I began to start thinking about it. Why is it interesting for the film directors and so on...

Jelllyjam, uhuh. Well, me too concerning the films. Have you seen "Identity"? And I guess, film directors are interested in EVERYTHING!

Kim_Berly, "Identity"? I don't think I saw it... Who plays the main role?

Jelllyjam, John Cusack, Ray Liotta, Alfred Molina, Amanda Peet, Rebecca De Mornay, Clea DuVall, Jake Busey. You see that there is a star cast in the film. The film is quite interesting, the end is unexpected. The plot is intricate. If u like thrillers, i advise u to watch it.

Kim_Berly, how is this film called in Russian? Oh, John Cusack...) Is he that handsome guy who always plays in comedies and melodramas?)

Jelllyjam, i'll try to reproduce it: Идентификация! That's it! Uhuh! Cusack is handsome. He plays in comedies and melodramas all right.