No matter how many words you can define, your vocabulary isn’t like a dictionary. Your mind stores language not as a list of words, but as a network of categories, properties, and meanings, with stronger connections between related words, like newspaper and magazine, than unrelated ones, like wallet and avalanche.
At six months old, a baby probably doesn’t know what wallet or avalanche means—but even at such a young age, months before children start talking, they do understand some basic nouns, like ball and dog. And a new study suggests that the few words infants know are structured in their minds the same way as an adult’s vocabulary, in a complex web of related concepts. The evidence: When words have similar meanings, babies can get confused. That confusion hints that babies know more about language, at a younger age, than scientists have found before.