First The Dress, now The Legs: Why is the internet so obsessed with optical illusions?

Are these legs shiny and oily, or are they legs with white paint on them? That’s the first question. The second question is: why do we care? Ever since the fateful first light of 25 February 2015, optical illusions have become the internet’s currency. “Is this dress white and gold or black and blue?” whispered the world wide web on that day, paving the way for our news sources to be replaced by a constantly updating feed of hidden cigars in brick walls, phones concealed in carpets, and a lonely Cheese & Onion Bake secreted in some Steak Bakes.