Predictors of Reading Skill Development in Children with Early Cochlear Implantation

Abstract

In Brief Objective The present study sought to document the word reading and comprehension levels attained by children who were implanted by 5 yr of age. It was hypothesized that the improved speech perception abilities acquired with cochlear implantation would promote phonological coding skills and facilitate the acquisition of beginning reading skills. Design Three subtests from diagnostic reading assessment batteries standardized on hearing children were administered to 181 children between 8 yr 0 mo and 9 yr 11 mo of age who had 4 to 6 yr of implant experience. In addition, a battery of processing measures was administered including a lexical decision task, a rhyme task and the digit span subtest of the Wechsler Intelligence Scale for Children. Results Over half of the children scored within the average range for their age compared with the normative data for hearing children. Reading competence was associated with higher nonverbal intelligence, higher family socio-economic status, female gender and later onset of deafness (between birth and 36 mo). After variance due to these child and family characteristics was removed, reading competence was associated with mainstream educational placement, use of an updated implant speech processor with a wide dynamic range, and speech processing characteristics that included longer memory span and use of phonological coding strategies. Reading outcome was most highly predicted by linguistic competence and, secondarily, by speech production skill. Conclusion Children who experience severe to profound deafness early in their development have a better prognosis for normal literacy development than ever before. To the extent that use of a cochlear implant is associated with greater use of phonological coding strategies for decoding print, longer working memory spans for short-term storage of phonemes, words and sentences and accelerated language development for reading comprehension, it should have a facilitative effect on the acquisition of literacy. Delayed reading development has been reported in most studies of academic achievement in the prelingually deaf population. In this study, reading scores averaged mid-2nd grade, which is close to an age-appropriate level compared with hearing children. There was, however, a wide range of individual performance, from 1st to 10th grade level. Characteristics of the children and their families accounted for 25% of this variance. There was a significant advantage for 9 year olds over 8 year olds, for girls over boys, for children with acquired over congenital hearing loss, for children with greater intelligence and from families with higher incomes/education. This study highlighted the importance of controlling for these characteristics before analyzing any other sources of variance in reading outcome. The use of phonological coding strategies and longer memory spans also was conducive to early reading acquisition. However, the largest amount of added variance in reading scores was accounted for by the children's speech and language skills. Children with the most intelligible speech and highest level of syntactic complexity and lexical diversity in their language were the best readers.