RE: divided plate..
Not that I mix it up on my plate, but I will often spear a piece of meat, smear it in my mashed potatos, and stab or scoop a green bean before the fork hits my mouth. Oddly, I tend to do this with the curved side of the tines down.
I guess I don't have a real problem with mixing food. My daughter doesn't either, but my oldest brother once complained to my mother about me mixing food when I was about five. The sight of it on my plate was apparently disturbing to him. Wierd!