Media tracking firm comScore estimates that nearly half of internet display ads are not viewable, meaning that people can't see them either because they are loaded in places that don't show up on their screens or because publishers fraudulently serve layers of ads behind the page shown to the public.
But according to Sticky, a firm that uses eye-tracking technology to figure out exactly which ads people look at, the actual number of ads people see is closer to 14%. According to company president Jeff Bander, people's brains are trained not to look at certain places on a page, meaning many ads publishers serve are merely white noise.