The Extended Mind: The Power of Thinking Outside the Brain

by Annie Murphy Paul

Rather astonishingly, researchers have found that children’s “newest and most advanced ideas” about how to understand a concept or solve a problem often show up first in their gestures. Take, for example, a six-year-old girl faced with a classic “conservation” task. (Such tasks were first employed by the pioneering psychologist Jean Piaget to investigate the course of childhood cognitive development.) The girl is shown a tall, skinny glass full of water, the contents of which are then poured into a short, wide glass. Asked whether the amount of water remains the same, the girl answers no—but at the same time, her hands are making a cupping motion, indicating that she’s beginning to understand that the wider shape of the second glass accounts for the way the same amount of water fills it at a lower level than the first glass.