Yeah, and banner blindness is about more than just things that look like ads. The top and side bars of webpages traditionally contain information about the website as a whole, and are not relevant to the specific page you are viewing. You look there to navigate away from the page you are on, but ignore them when digesting the content you came to read. This would be true even if ads hadn't ruined our expectations, and has analogs in other media. In a book, you don't expect users to read the header/footer (page number, chapter, etc) each time they turn a page. Those are there to navigate through the book more quickly, but are ignored once you get to where you want.