While viewing a webpage, you might find that you immediately looked at the center of the page, avoiding the edges.
You might also scan the screen from left to right if you read English.
People have a mental model of where things are on a computer screen and they can quickly make judgments on where their eyes should go. As designers we should take advantage of this expectation when we design our own webpages. You can also pull people away from this tendency with images or movement.