"Is it silly and backward to wonder how the onslaught of nonstop input—most of it trivial—is altering how we think? Before GPS, scientists have found, people made intricate “mental maps” that guided them to destinations; with use, the spatial region of the brain actually grows larger. Rely on GPS, and your unaided ability to find your way withers—and so, perhaps, does some of your gray matter. If we rely on Facebook et al. as an interface with reality, what withers? What shrinks?"