Spanish Castle Illusion, Customized

I found this on Slashdot....very cool. It's a customized version of the Spanish Castle Illusion (the image below is from our recent trip to Las Vegas) which I made at http://www.myopticalillusion.com/.


Directions: Remove your mouse from the image above. Focus on the black dot in middle of the image for twenty seconds. Keep focus on the dot while you move your mouse back over the image, and the image will appear to be in color. What's cool is that once you do move your eyes away from the dot, you see the picture for what it is: a black a white image.

So, how does it work?

This illusion forces your brain to see color in a black and white photo. It works by first saturating your visual memory with shade and line data, which occurs when you stare at the first picture for more than ten seconds or so. Upon flipping to the second picture, the spectral opposite of the original color data is imposed on the grey lines and shading of the photo.

If the illusions works, it will immediately begin to fade once you move your eyes. This is because a saccade, or a quick lateral eye movement, will effectively "clear" the visual memory buffer with the assumption that the eye is seeking a new pattern to focus on. Even though the visual memory buffer clears with a slight glance in any direction, you will still see a slight fading of illusory effect as the neurochemical saturation in your visual cortex fades.

That explanation was taken from an article at tripzine.com, which looks to be a site devoted to the study of all things scientifically psychedelic, so take it with a grain of salt (or whatever else floats your boat, I guess).