If you buy into the stereotype of vain, stupid actors, this might be surprising. I am occasionally guilty of this myself, as has recently been pointed out to me. In general, any specific person doesn’t “fit” any generalization, and actors are no exception; while doing theatre I met people who filled the possibility space of human attributes and behaviours.
The thing about acting that actually does generalize reasonably well, however, concerns something that actors who work on the inner art of acting do, which is the practice of scene study. Scene study is when you take a scene from a dramatic work and, by doing very specific research and rehearsal, attempt to fully understand a character from the inside.
When scene study works, one is granted access to a kind of knowledge about another person that exists nowhere else in my experience. My coach in the art of scene study used to use fairly radical techniques to trigger understanding, and it was infuriating…but it worked. Arif (your trace persists, dahling) would tell us, very simply, “I don’t believe you.” He would ask us how we felt about something intrinsic to the character, and would then pull that rug out from under us. He would ask inappropriately intimate questions. And he would slowly, slowly, drag us out of our comfort zones and into a place where we could legitimately experience what it means to assume an identity which was not our own.
If you’ve ever wondered why some actors seem to be damaged by roles, this is why. They take on darkness, and in doing so they put themself at risk, emphasis on “self”. Mapping oneself onto a monster, or, equally, a monster onto oneself, carries the risk that new synapses will form in the brain, and that the monster will live on in those pathways.
Having said that, being inside a character – any character – is of tremendous value as a writer attempting to build a work that includes characters of substance. I think there’s a kind of understanding about the truth of a character that can only really come from being inside that character’s head. Sometimes, as a writer, you need that. Not always, mind; sometimes you want to create a work with a very particular shape, and the characters serve the needs of that form. But when the characters need to live in the reader’s imagination, there’s no substitute for having been inside a character far enough to know when to believe yourself.