But do actors do this because it helps them remember the lines better or because it's essential in order for the delivery to sound natural and not memorized. It has to be something that the actor, impersonating the character, would have said without being prompted. So if you can internalize the character, then the script is a logical result of what that character would naturally say--reducing the amount of exact memorization needed. But I'm not sure that it's necessarily that it improves memory itself. (Not saying it doesn't but there's a confound here, from a scientific perspective, that isn't easily disentangled).