It is "the first case known to doctors of a person being able to feel, see and deliberately move a limb that doesn't exist." The woman underwent an MRI and when doctors asker her to move her imaginary third limb, her brain responded as if she really had the arm. Her visual cortex activity also indicated that she saw the arm. (Via Arbroath)
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. Come and hear Mark speak at the ALA conference in Chicago on July 1.