Date of Completion


Embargo Period



Bilingualism, Cochlear Implants, Morphology, Language Acquisition, Bimodal Bilingualism

Major Advisor

Diane Lillo-Martin

Associate Advisor

William Snyder

Associate Advisor

Marie Coppola

Field of Study



Doctor of Philosophy

Open Access

Open Access


This dissertation investigates the acquisition of English morphology in two bilingual populations: hearing American Sign Language (ASL)-English bilinguals and Deaf ASL-English bilinguals with cochlear implants (CIs). Such a study is important to not only help address more general theoretical questions about the role of input in language acquisition, but also to help establish expected outcomes in these populations vulnerable to over-diagnosis of language disorder. Spontaneous and elicited speech samples were used to determine accuracy rates in obligatory contexts for ten English morphemes (definite and indefinite determiner, progressive –ing, (un)contractible copula, (un)contractible auxiliary, regular plural, regular 3rd person present, and regular past tense), overall morphological accuracy and mean length of utterance (MLU). Results from the hearing bilinguals were remarkably similar to previous findings with monolingual children, although sometimes the bilinguals were at the lower end of the typical range. The results from the bilinguals with CIs were then compared to the hearing bilinguals because, other than the delayed exposure to spoken English before implantation, their language environments were very similar. The bilinguals with CIs showed dissociation between MLU and grammatical morpheme accuracy not seen in the bilingual comparison group or typical monolinguals. This was due to the fact that even at the lowest MLUs, morphological accuracy was high, suggesting that older children with cochlear implants go through a developmental phase in which they speak telegraphically, like younger typical hearing children, yet possess relatively sophisticated morphological knowledge, unlike hearing children in the same developmental phase. Furthermore, results from both spontaneous and elicited speech showed that, while there were many similarities between the hearing bilinguals and those with CIs, the latter group is particularly susceptible to difficulties with the English plural (there was not enough data available to assess the past tense and 3rd person present). These difficulties could be due to the nature of hearing through a CI, or the delayed English language exposure.