If anyone hasn't read Keaton reminiscing on the Batfilms, you should check out this interview
from a couple months back. Lots of great insight into how he chose to act in the role. It's a shame there is this misconception that both he and Burton only scratched the surface of what the character was about. If anything I think much of what they did flew over a lot of people's heads.
Anyway, here is the most interesting quote from that piece. I'd pay a fortune to get a hold of this gem:
There was a thing that never got in that was really interesting. I went to Tim and said that we should see if we could do a scene that showed the transition and Tim was really great about these things so we tried. I wanted to see and to show that transition when he goes from Bruce Wayne to Batman, the time when he’s about to don the suit and go out and wreak some havoc. That’s not a casual thing, obviously, it’s not putting on a jacket to go out for the evening. So what is that transition like? So there was a thing we did early on that showed him going into a sort of trance and it justified this shift in him. So we did that scene and it never made it into the film but I think helped me in a way. It was part of the way he became this other thing and even if you didn’t see it, it was part of the character and the way we created him. Tim was always open to that. Jack and Kim come to him, too, chipping in with ideas and it was a really creative environment.”
Incidentally this would have helped Bale's performance more, as his portrayal is really out there. Surprised Nolan completely glossed over this, as he painstakingly showed everything else about Batman's creation.