Identity question

"The Simpsons Movie" is out on DVD today and is the subject of much advertising in the media. But what of the actors who voice the various Simpsons and other characters - or any actor in fact - how much do they identify with their characters. When Dan Castellana ("Homer") looks at a picture of Homer - does he think of himself - or does he think of Homer the character? How much does "voicing it" make it real - for instance, when people do role plays of situations, that's to practice for real life. How much does acting/voicing differ? (More thought/investigation needed.)