Optical illusions are proof that while the human eye is a wondrous feat of natural design, a biological marvel and rather damn useful for getting around - they're not beyond being tricked.
Artists, psychologists and scientists have reveled in devising fiendish pictures that leave us rubbing out retinas in disbelief for centuries - whether it's fusing two pictures into one, making two dimensions pop into three or causing colours and shapes to dance like they're alive.
With the help of the brilliant optical illusion website
