Just a quick post to show you something really cool that came up on my facebook this evening while doing homework.  It's a fun little experiment, and thinking about it hurts my brain.  The human optical system is so intricate and odd, I wish I understood how this works.  If you know, PLEASE post so in the comments!

Instructions:

1.) Click the picture to open a larger version
2.) Focus on the red dot on the girl's nose for 30 seconds or longer
3.) Turn your gaze to a wall/blank surface
4.) Blink rapidly and check out what appears on the wall!
NOTE: Blank surface isn't necessary, just shutting your eyes works, but I think that blinking while staring at the blank surface actually makes it easier to see.

After posting this post, and having the above picture also up on facebook, I began getting all sorts of these similar ones.  So here's the best other one I've received.  Check it out.  To make the whole picture work, click on it to get a larger image.  Stare straight at the center of the picture for the entire run of the GIF video.