The Supermarket Effect
Watch this video - it's fascinating.
At ORCHID, we use this in our writing training and Presentation Skills course when we discuss structure. We call it the 'Supermarket Effect'. Believe it or not, it can be used in writing in a very similar way.
We are creatures of habit, always looking in the same place for our purchases (information). But if the information the audience is expecting to get isn't where they expect it to be, but they still want it, you can put the info you want to get across between the start point (opening paragraph) and the point they want to get to. That way, you can encourage them into a spontaneous purchase (ie. take on board the information you want them to have), and you stand more chance of getting your key messages across.
It's a great way of approaching structure. Rather than writing in an essay style ("Once upon a time, all this happened, and they lived happily ever after), which is what we are exposed to from cradle to career, mix it up a bit and the surprise you cause will have a much greater impact.