One of my favourite subjects ever in school was Vision Science. I attended lectures and listened in religiously. I asked all the questions, and when there was just not enough time for them in class, I followed my professor to her office and talked vision science with her for what seemed like hours afterwards. I loved it so much and was so inspired that I considered switching major and school to follow my professor to her new teaching post. But, I decided that I didn't know what to do with myself should I venture into researching in that field (and of course, I was supposed to attend med school and everything, but that's another story). Plus, researching the field required dedication and focus that I just couldn't commit to at the time.
Anyway, all of this is a round about way of saying I really love vision science and that whenever I see articles on the subject I have to read them. Recently, Scientific American (Mind) ran an article on how we perceive 2D cues into 3D visuals - basic vision science stuff. One piece of information that caught my attention was the idea that somehow the sun was stuck to our head.
Amazingly, the brain’s assumption that light shines from above the head is preserved even when you rotate your head 180 degrees. Ask a friend to hold this page right side up for you. Then bend down and look between your legs at the page behind you. You will find that, again, the switch occurs, as if the sun is stuck to your head and shining upward from the floor. Signals from your body’s center of balance—the vestibular system—guided by the positions of little stones in your ears called otoliths, travel to your visual centers to correct your picture of the world (so that the world continues to look upright) but do not correct for the location of the sun.So even when your world is topsy-turvy, trust the sun to always be right side up for you.