Research Study on Communicative and Linguistic Abilities of Italian Deaf Children with Early Cochlear Implantation

Project location: ITALY, Rome
Project start date: December 2010 - Project end date: December 2011
Project number: 2010-62
Beneficiary: CNR

Lexical and grammar comprehension and production in Italian deaf children who had received a Cochlear Implant (CI) in the second year of life have been investigated and these children have been compared to two control groups of hearing children, matched for chronological age and time since CI activation. The first step was the selection of an adequate set of tools that allow us a precise evaluation of relevant aspects of the linguistic skills of this population of children. The protocol consisted of the following tests for direct observation: i) a cognitive scale to assess non-verbal I.Q. (Leiter International Performance Scale- Revised); ii) the lexical-phonological test, to assess lexical comprehension and production, also taking into account Italian phonology in both, comprehension and production; iii) the grammar comprehension test, to evaluate morpho-syntactic comprehension; and iv) the sentence repetition task, to assess the ability of children to imitate verbal stimuli, focusing on morphology and syntax.

The protocol of cognitive and linguistic evaluation has been administered to 17 deaf preschool children with Cochlear Implant. Each child with a CI was matched with two hearing children, considered as controls: one child with the same chronological age as the deaf child and one child whose chronological age corresponded to the amount of time that the Cochlear Implant had been activated in the deaf child [referred to as "TIA (time since implant activation) children"].

The differences among the groups of children were tested using one-way analysis of variance (ANOVA). In cases in which significant differences were found, planned comparisons were performed, comparing children with CI to children matched for chronological age and TIA children. The results showed that in lexical comprehension, children with a CI performed significantly worse than same-age hearing children, whereas there was no significant difference when comparing them to children matched for time since CI activation. When the types of errors were considered, we found that children with a CI made the same number of semantic errors as the same-age hearing children, suggesting that the differences in lexical comprehension were not due to differences in cognitive maturity. In fact, children with a CI made a greater number of phonological errors than same-age hearing children yet a similar number of errors when compared to the TIA children, suggesting some limitations in phonological processing. Considering grammar comprehension, children with a CI performed similarly to the TIA children in terms of both, the score obtained and the number of children who passed the test (for children with a CI, the test level corresponded to time since IC activation). Only 4 (27%) of the children with a CI reached the level of their chronological age, and only 2 of them passed this level. Because of this small number, no comparisons were made with same-age hearing children. These findings suggest that children with a CI have not reached the level of grammar comprehension that coincides with their chronological age.

With regard to language production, in the lexical task, children with a CI produced a similar number of words with respect to the same-age hearing children. However, the number of correct answers following a phonological cue was lower in children with a CI when compared to the two control groups, which confirms that the children with a CI still have some limitations in phonological processing, as observed in lexical comprehension. In the sentences repetition task, children with a CI repeated significantly more sentences with errors and made a higher total number of errors compared to same-age hearing children. Regarding the specific type of error, children with a CI omitted or substituted a higher number of words than same-age hearing children, though the difference was not significant. With regard to the parts of speech, children with a CI omitted a higher percentage of definite articles than same-age hearing children. These findings may be related to the fact that in many cases, some free grammatical morphemes (such as articles and clitics) have scarce semantic content and are short and unstressed; thus they are much more difficult to perceive and identify than other parts of speech, which obviously influences the ability to produce (or reproduce) them. The specific deficits in morphology (in particular, in free morphology) could due to the perceptual problems that continue to be present despite the CI. These problems negatively influence the processing of acoustic events (e.g., verbal strings, phonemic sequences, and rhythms in sequence) and thus could cause atypical construction of morpho-phonological representations.

Evidence that the activation of a CI in the second year of life in deaf children without additional impairment can result in the acquisition of good language skills has been found, though comprehension is not completely age-appropriate and some limitations in phonological and morphological skills are still present three years after auditory reafferentation.

From a clinical perspective, understanding the strengths and weaknesses in linguistic skills in deaf children with a CI could contribute to developing better targeted interventions.

In order to recruit children (this task was been very difficult) speech therapists and neuropsychiatrists operating in public services, within the national health service or privately have been contacted. Kindergartners and schools in Rome have also been involved for the recruitment of the children of the control groups.

On these topics, two manuscripts have been prepared (in press) Namely: i) a paper in a peer reviewed ISI journal; ii) a chapter in an edited book:

i) Caselli, M. C., Rinaldi, P., Varuzza, C., Giuliani, A., Burdo, S. (2012 -in press-). Cochlear implant in the second year of life: Lexical and grammatical outcomes. Journal of Speech, Language, and Hearing Research.

ii) Caselli, M. C., Rinaldi, P., Baruffaldi, F. (in press). Il bambino sordo con impianto cocleare: Abilità linguistiche, scelte educative e valutazione. Atti della 1a Conferenza Nazionale sulla Sordità.

Furthermore, partial results of this project have been presented in two different Conferences:

Rinaldi, P., Baruffaldi, F., Brillo, S., Caselli, M. C. (2011). Abilità grammaticali in bambini sordi con impianto cocleare: analisi del linguaggio spontaneo. XXIV Congresso Nazionale AIP. Sezione di Psicologia dello Sviluppo. Genova, 19-21 settembre 2011.

Rinaldi, P., Baruffaldi, F., Muzzioli, C., Proietti, V., Caselli, M. C. (2012). Abilità lessicali e pragmatiche in bambini sordi con impianto cocleare. Giornate di Neuropsicologia dell'Età Evolutiva, VII Edizione. Bressanone (BZ), 18-21 Gennaio 2012.