Empathy
From the same interview I linked to last week, Laura Dern talks about how she needs to have empathy for her characters (as do her directors). To judge them makes it impossible for her to be as free and creative as she needs to be.
In a recent LA Times roundtable of Hollywood actresses, Jennifer Aniston, Emily Blunt, Jessica Chastain, Gugu Mbatha-Raw and Shailene Woodley touch on the same subject.