The Mind's Assumptions

Yahoo had a pretty cool thing on why Optical Illusions Trick Our Minds. The basic answer is our minds try to see things in the simplest ways. Ways we're used to seeing things, or feel is 'normal'. So if it's fast enough, something out of the 'ordinary' might slip right by. I can see that. I know that in speed reading courses taken as a teen we were told to only read certain words and skip the small words like 'a, an, from, for' etc... assume they're there. Also reading only consonants and letting our minds fill in the rest. The mind assumes they're there. It's also why proof-reading pages of something you've written often times allows many errors to slip through that someone who didn't write it might catch. Your mind knows you 'meant' the right word, or spelling and simply assumes it's there. However, it's also why no matter how many people you have proof something, errors can still slip through... everyone assumed it was there.