Catbutt. Typical.
Quote:
Originally Posted by Espy
Hm, yeah, so this would suggest your eyes are constantly moving/twitching down while playing. -headscratching- I mean, I see how that works, but that does sound less plausible.....huh. It could definitely be an unconscious thing?
|
It's EXTREMELY unconscious -- and in fact it doesn't directly have anything to do with eye movement, but with how your brain processes input.
Animal brains are tuned to filter out things that are constant. This is why you stop noticing how cold water is after a while, and smells fade into the background, and you can tune out background noise but still react when someone says your name.
This happens for vision, too. When things are still, they don't command particularly much attention, but if something suddenly starts moving, you instantly become aware of it.
This filtering process allows us to focus our attention and not worry about having to process all of the sensory input that our brains are receiving. We can work with the important stuff we perceive instead of getting overloaded by absolutely everything happening around us. (There are various disorders that interfere with this process -- ADHD is one of them; the reason ADHD sufferers have difficulty focusing is because this filtering doesn't do a good enough job and things that most people could ignore instead get flagged by your subconscious as needing to be addressed.)
But vision is the primary sensory input for humans. When this shortcut in the brain doesn't jive with what we consciously understand reality is supposed to be like, we NOTICE.
So in this case, your nervous system has gotten centered not around the trees moving upward, but on the sled moving downward against what we understand is an unmoving background of trees despite our eyes saying the sled is stationary and the trees are moving. Your brain has made the association "things that are currently fixed in my field of vision are moving downward relative to my background reference."
But not only is the SLED moving downward against this perceived background, the rest of the screen is too! So when the trees and the sled are gone, everything else is still not moving upward in your field of vision, and so you perceive it as going downward.
Eventually your brain figures out that this isn't the way the world works and things straighten out, but in between, you experience that visual illusion.