Even before uttering their first words, babies master the grammar basics of their mother tongue. Thus, eight-month-old French infants can distinguish function words, or functors—e.g., articles (the), personal pronouns (she), or prepositions (on)—from content words—e.g., nouns (rainbow), verbs (to drive), or adjectives (green). Functors are frequently encountered because there are fewer of them, and they