The Neuroscience of Yorick's Ghost and Other Afterimages; The Science of Perception; Special Editions; by Stephen L. Macknik and Susana Martinez-Conde; 4 Page(s)

Alas, Poor Yorick! I knew him, Horatio; 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 William Shakespeare's Hamlet might have said, had he been looking at a vintage Pears' Soap advertisement bearing court jester Yorick's skull, rather than holding an exhumed and rotting Danish cranium. Stare long enough at the skull in the ad, and it will be "burned" into your vision even after you look away.