Children are extraordinarily good at finding meanings for words—and words for meanings. In fact, they seem to be“primed” for this task before they even learn to speak, perhaps because words and their meanings help them organize and categorize the bewildering world that surrounds them.

In one experiment, a group of nine-month-old infants were shown a series of rabbit pictures as the experimenter said “a rabbit” each time. Another group saw the same pictures, but heard a tone instead. Both groups were then shown two pictures, one of a rabbit and one of a pig.

The group that had heard the “rabbit” label looked longer at the new animal. The group that had heard the tone made no distinction.

Evidently, hearing a label had helped the first group of infants recognize the category “rabbit,” making it easier to see the pig as a new type of animal.

Children have a very reasonable word-learning priority: they want to know the names for the people and things they've been seeing since they were born. So their first words tend to have meanings that are very close to home. In another experiment, a young boy over an eight-month period beginning when he was eleven months old produced forty three words. Among them, thirty-one are nouns—the type of word best suited for naming people and objects.

Among the non-nouns likely to show up in any child's “first fifty” list are words to comment on disappearance and absence, the success or failure of an action, denial or rejection, calls for attention, vertical motion, and containment or attachment.