The Extended Mind: The Power of Thinking Outside the Brain

by Annie Murphy Paul

At first, Hutchins observed, Richards reached for ways to spread the burden of the task across his own body and across the tools he had at hand. He “subvocally rehearsed” the numbers he was computing, repeating the digits under his breath—using his voice and his auditory sense to expand the capacity of his working memory. He traced the columns of numbers being added with his fingertip, using his hand to help keep track of the masses of information he was managing. With a pencil, he jotted down intermediate sums in the margin of the navigation chart, fixing in place a kind of “external memory,” in Hutchins’s phrase. And he pulled out a calculator, using it to relieve his brain of the burden of carrying out mathematical operations. Still, laboring on his own, Richards began to fall behind. He recruited yet one more resource: the mental ability of his teammate, Quartermaster Second Class Silver. The addition of another mind created a new challenge, however: how to figure out, on the fly, the best way to divide up the complex and fast-paced task.