Phew, to see my idea landed! It's funny, but I always see those tilting things at first glance. Well, let's say it's a talent or so, and there are those with the talent seeing it at once, and those who can ignore it as an irrelevant detail. I just seem to be too linear to ignore it. :) There's this website with optical illusions, http://www.davidpbrown.co.uk/optical-illusions/after-image.html, where you can see how easy we can be tricked by our own eyes! But uh... on relying on senses, it's the eyeballs that always come first (I've never felt braille images and listening to images with my eyes closed, hmmm, hard thing), though?