Hey, optical illusion fans! Is Square A a darker shade of gray than Square B? Or could this be . . . only an illusion??
Okay, I know you already know the surprising answer, but it's still cool to check it out here. Illusion and explanation both courtesy of Professor Edward Adelson at my alma mater, MIT. Clever flash demos of other illusions available here. Hat tip to the MIT alumni blog at www.wordpress.com.