Why Opti­cal Illu­sions Like These Make Your Brain Go Hay­wire (Wired): “Uni­ver­si­ty of Bris­tol researchers dis­cov­ered this illu­sion in the ear­ly 1970s while look­ing at the tiled wall of a café. Hence the name, Café Wall Illu­sion. The gray lines in between the rows of white and black squares seem to con­verge, but they are…