Early Vocabulary Profiles of Young Deaf Children Who Use Cochlear Implants.

Purpose: This study examined vocabulary profiles in young cochlear implant (CI) recipients and in children with normal hearing (NH) matched on receptive vocabulary size to improve our understanding of young CI recipients' acquisition of word categories (e.g., common nouns or closed-class words). Method: We compared receptive and expressive vocabulary profiles between young CI recipients (n = 48; mean age at activation = 15.61 months, SD = 4.20) and children with NH (n = 48). The two groups were matched on receptive vocabulary size as measured by the MacArthur-Bates Communicative Development Inventories (Fenson et al., 2006): Words and Gestures form. The CI group had, on average, 8.98 months of hearing experience. The mean chronological age at completing the MacArthur-Bates Communicative Development Inventories was 23.99 months (SD = 5.14) for the CI group and 13.72 months (SD = 1 .50) for the NH group. Results: The CI group had a larger expressive vocabulary size than the receptive vocabulary size-matched NH group. The larger expressive vocabulary size was associated with the group difference in social words but not with common nouns. The analyses for predicate words and closed-class words included only children who produced the target categories. The CI group had a larger proportion of predicate words than the NH group, but no difference was found in closed-class words in expressive vocabulary. Conclusions: Differences found in expressive vocabulary profiles may be affected by spoken vocabulary size and their age. A further examination is warranted using language samples to understand the effect of language input on children's vocabulary profiles.