INFANTS EARLY VERBAL IMITATION AND THEIR LATER LEXICAL DEVELOPMENT

Imitation and lexical development of infants (n = 20) were examined longitudinally at ages 10, 13, 17, and 21 months. Infant lexicons were determined from maternal interviews. Words, vocalizations, and actions either outside or within infants' current repertoires were presented at ages 10 and 13 months. More verbally advanced 13-months-olds imitated more words inside their repertories, but only reproduction of words outside their current lexicons predicted their future lexical development. When early vocabularies were statistically controlled, infants who imitated more words outside their repertoires at 13 months acquired larger noun lexicons by 17 months and larger non-noun lexicons by 21 months. Imitation of other behaviors was not related to vocabularies. Infants' early imitation of words not in their repertoires predicts and may facilitate their future lexical development.