An excellent article on acting and the Oscars from Ann Hornaday in The Washington Post. It includes this:
Moss, who coached Helen Hunt for her role in “As Good as It Gets” and Hilary Swank for both “Boys Don’t Cry” and “Million Dollar Baby,” believes that the difference between impersonating and acting — and between good acting and great acting — lies in the psychological research and reflection an actor does before going on camera, accessing personal memories and emotions to bring oneself into a role rather than just playing it. Hoffman’s performance, Moss says, is “a very good example of a performance that has enormous technique, filled to the brim with what I call emotional justification, and that’s the private work the actor does to identify within himself the emotional cost of a character’s desires.”
Hornaday’s choices for the acting Oscars: Hoffman and Dillon, Huffman and Adams.