Ok, got to admit this intrigued me. Wondering what and how they are assessing this.
As others have said on the interview - be yourself, the interviewer knows what he/she is looking for and will determine if you fit. And remember, it's not a bad thing if you don't.
My interview was with a group of three, we all had to collectively draw one picture. I don't think I'm allowed to say what it was though.