I read fiction about 1/3 of the time and nonfiction 2/3s of the time. When reading non-fiction I often spend idle moments in my day lost in abstract thought about concepts related to the non-fiction book I'm reading. I've noticed when reading novels, I'm far more observant about people in my personal life and their thoughts and motivations. This is especially true when reading works with thoughtful and observant POV characters (especially detective fiction and mystery novels). I think fiction, like music, can serve to frame your mind-state in a certain way.