Grammatical morphologic development in pediatric cochlear implant users may be affected by the perceptual prominence of the relevant markers.

The goal of this study was to test 2 hypotheses about language development in pediatric cochlear implant (CI) users. The "language instinct" hypothesis states that children with CIs will develop language in the same sequence as children with normal hearing, but in a delayed fashion. In other words, noun plurals will develop first, and the use of the uncontractible copula and regular past tense will follow. An alternative hypothesis (the "perceptual prominence" hypothesis) is that the pattern of language development in CI users will be strongly affected by the perceptual prominence of the relevant morphological markers. This hypothesis predicts that the uncontractible copula will develop first, followed by noun plurals, and then by regular past tense. A sentence completion task was used to measure the performance of 9 pediatric CI users and compare it to that of several groups of children with normal hearing. The results from the CI users were consistent with the perceptual prominence hypothesis. In particular, the scores for the copula probe were higher than those for the noun plural probe for 8 of the 9 CI users. This result represents a rather striking inversion with respect to the usual development pattern in children with normal hearing and even in children with specific language impairment. If the perceptual prominence hypothesis receives further support in future studies, clinicians who work in language rehabilitation of CI users may choose to target those aspects of grammar that are less acoustically prominent to these children. In addition, and from a theoretical standpoint, these results suggest that although there may well be an innate language acquisition mechanism, patterns of language development can be strongly affected by the acoustic input.