This study had two key objectives. First, to examine whether children who receive cochlear implants (CIs) before the age of 3 years and who are experienced implant users (mean length of CI use = 6 years; range = 4 to 9 years) show deficits on a word learning task relative to their hearing peers. Second, to examine whether variation in age at implantation within the first 3 years of life relates to later word learning abilities.
Twenty-one 6- to 10-year-old children with CIs, 21 chronological age-matched (AM) hearing children, and 21 vocabulary-matched hearing children completed an auditory word learning task in which they were required to learn the names of eight rare animals. Comprehension and production probes tested their learning of these unfamiliar words.
The children with CIs performed similarly to AM peers on the comprehension phase of the word learning task. Their production performance was significantly poorer than the AM group but was in line with that of their younger vocabulary-matched hearing peers. Differences between the CI and AM groups were accounted for by differences between the groups in terms of their existing vocabulary knowledge. Within the CI group, there was no evidence of an association between age at implantation and performance on the word learning task, but existing vocabulary size showed strong positive correlations with word learning performance, after adjustment for chronological age.
When implanted by the age of 3 years, and with over 4 years CI experience, 6- to 10-year-old children are able to perform similarly to their AM hearing peers in terms of their comprehension of newly learned words. Producing accurate phonological forms of newly learned words may be a more challenging task for children with CIs, but their production performance is consistent with their vocabulary size. This cross-sectional study provides support for a relationship between existing vocabulary size and novel word learning skills in children with CIs; future longitudinal studies should test the hypothesis that this relationship is developmentally reciprocal.
1University College London, Institute of Cognitive Neuroscience, London, United Kingdom; and 2Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa, USA.
ACKNOWLEDGMENTS: This work was supported by grants from the National Institutes of Health (NIH)-National Institute on Deafness and Other Communication Disorders (P50 DC000242; principal investigator, Bruce J. Gantz), the British Academy Leverhulme Fund (SG131650; principal investigator, Hannah Pimperton), the Experimental Psychology Society (Study Visit Grant), and the University of Iowa Obermann Center for Advanced Studies (Interdisciplinary Research Grant). The content of this project is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute on Deafness and Other Communication Disorders or the NIH. The following people provided support, assistance, and feedback at various points in the project: Jacob Oleson, Marcia St. Clair, Camille Dunn, J. Bruce Tomblin, Dorothy Bishop, Julie Hsu, Kelsey Klein, Margaret Dallapiazza, and Marlea O’Brien. Special thanks go to the families and children who participated in the research.
The authors have no conflicts of interest to declare.
Address for correspondence: Elizabeth A. Walker, Department of Communication Sciences and Disorders, University of Iowa, 250 Hawkins Drive, Iowa City, IA 52252, USA. E-mail: firstname.lastname@example.org
Received July 7, 2016; accepted January 9, 2018.