“Infants are born with a language-independent system for thinking about objects,” says Elizabeth Spelke, a professor of psychology at Harvard. “These concepts give meaning to the words they learn later.” Because languages differ in how they approach objects, many scientists suspected that children must learn the relevant concepts as they learn their language. That’s wrong, Spelke insists. Spelke and Susan Hespos, a psychologist at Vanderbilt University in Nashville, Tenn., did some clever experiments to show that the idea of tight/loose fitting comes before the words that are used/not used to describe it. When babies see something new, they will look at it until they get bored. Hespos and Spelke used this well-known fact to show different groups of 5-month-olds a series of cylinders being placed in and on tight- or loose-fitting containers. The babies watched until they were bored and quit looking. After that happened, the researchers showed them other objects that fit tightly or loosely together. The change got and held their attention for a while, contrary to American college students who failed to notice it. This showed that babies raised in English-speaking communities were sensitive to separate categories of meaning used by Korean, but not by English, adult speakers. By the time the children grow up, their sensitivity to this distinction is lost.