On average, online readers are actually skimming information on webpages. Web page visitors apparently spend as much time “reading” as trying to figure out how to navigate the page and checking out the images. The eye movement while skimming the material differs from that of in print. Online, eyes follow an F Pattern, first in a horizontal movement across the upper part of the page, then a second horizontal movement followed by a vertical movement. All in all, users have now taken in a mere 20% of the material!
Source: http://www.nngroup.com/articles/how-users-read-on-the-web/
