Do words facilitate object categorization in 9-month-old infants?

Previous research reveals that novel words highlight object categories for preschoolers and infants as young as 12 months. Three experiments extend these findings to 9-month-olds. Infants were familiarized to slides of animals (e.g., rabbits). Infants in the Word condition heard infant-directed word phrases ("a rabbit") and infants in the Tone condition heard tones. During familiarization, infants' visual fixation was enhanced on trials with sounds (either words or tones), relative to silent trials. On test trials, a new exemplar from the familiar category (e.g., rabbit) was paired with a novel animal (e.g., pig). Infants in the Word condition showed greater attention to novelty than those in the Tone condition. A third group of infants who heard content-filtered words responded similarly to infants in the Word condition. Implications of the facilitative effects of words and content-filtered words on object categorization are discussed within a framework describing infants' emerging appreciation of language over the first year of life.