Input frequency and children's first words

In once-monthly, hour-long recordings of uncontructured interactions at home between parents and 45 children averaging 11-17 months old, the first productive words recorded for each child were examined for the frequency each word had been recorded in parent use. The first words the children produced tended to be ones their parents frequently addressed to the children, but evidence for a relationship with word frequency in input decreased as the children produced increasing numbers of words. The children seemed to progress rapidly from rote learning to learning words on a more principled basis.