The Neuroscience of Yoricks's Ghost and other Afterimages
Alas! Poor Yorick. I knew him well. A fellow of infinite jest, of most excellent fancy; he hath borne me on his back a thousand times; and now, how abhorred in my afterimage he is!
Well… that’s what Hamlet would have said
you can stare at the X in Yorick’s left eye socket for about 10 to 30 seconds, then look away at a flat surface such as a piece of paper, wall, ceiling or sky, and you will see Yorick’s afterimage as a ghostly apparition
Afterimages such as this one help us to understand how neurons in various areas of the brain adapt to the visual environment
The monkeys turn into an afterimage of Darwin’s portrait
fixate your gaze on the fly in the right image for 10 to 30 seconds:
look back at the fly on the cow’s nose, and the image will appear to have a perfect color balance
After a few seconds, the pink dots will start to adapt and fade. As the pink dots fade, a green afterimage replaces each dot
long-lasting red afterimage
clipped from: www.sciam.com 
