Moonwalking with Einstein: The Art and Science of Remembering Everything

by Joshua Foer

According to Baron-Cohen, two rare conditions may have conspired to produce Daniel’s savant abilities. The first is synesthesia, the same perceptual disorder that afflicted the journalist S, in which the senses are intertwined. By one estimate, there are more than a hundred different varieties of the disorder. For S, sounds conjured up visual imagery. In Daniel’s case, numbers take on a distinctive shape, color, texture, and emotional “tone.” The number 9, for example, is tall, dark blue, and ominous, while 37 is “lumpy like porridge” and 89 resembles falling snow. Daniel says he has a unique synesthetic reaction like that for every number up to 10,000, and that experiencing numbers in this way allows him to do quick mental math without pencil or paper. To multiply two numbers, he sees each number’s shape floating in his mind’s eye. Intuitively, and without effort, he says, a third shape, the answer, forms in the negative space between them. “It’s like a crystallization. It’s like developing a photo,” Daniel told me. “Division is just the reverse of multiplication. I see the number and I pull it apart in my head. It’s like leaves falling from a tree.” Daniel believes his synesthetic shapes somehow implicitly encode important information about the properties of numbers. Prime numbers, for example, have a “pebble-like quality.” They’re soft and round, without the jagged edges of numbers that can be factorized.