For most of us, smart devices or a simple pad of paper are our best memory aids, but at the World Memory Championships, winners can recall over 250 random words after being given 15 minutes to learn them, memorize a string of nearly 4,000 binary digits, or learn a 500-digit number in five minutes, a new world record set by champion Johannes Mallow. It's a stunning feat of memory, but one that requires intense concentration, often with the aid of earplugs, dark glasses, or other sensory deprivation tools. In a photo essay at Wired, David Vintiner has captured this year's competing champions, giving us a window into an easily quantifiable but deeply personal skill.