I was reading this article on Cracked.com, which is where I pretty much get all my information. The article deals with ways your memory can play tricks on you. One of the points they bring up discusses Selective Attention, which I found rather fascinating. The idea that you are only seeing what you want or need to see. You can take a test on YouTube which illuminates just how much we think we’re visually taking in of the world versus how little we really are.
Take the test and see (or don’t see) for yourself.