Children with Cochlear Implants : Cognition and Reading Ability

Sammanfattning: The present thesis investigated cognitive ability in children with severe to profound hearing impairment who have received cochlear implants (CIs). The auditory stimulation from a cochlear implant early in life influences most cognitive functions as a consequence of the plasticity of the brain in the young child. It is important to understand the cognitive consequences of auditory stimulation from CIs in order to provide adequate support to these children. This thesis examined three specific aspects of cognitive ability (working memory, phonological skill and lexical access), and reading ability in children with CIs, as compared to children with normal hearing in the same age. The relations between cognitive abilities and reading skills were also investigated, as well as the associations between demographic variables (e.g., age at implantation and communication mode), cognitive abilities and reading skills. The children with CI generally had lower performance levels than the normal hearing children in tasks of phonological and general working memory, phonological skills and lexical access. They had specific problems in tasks with high demands on phonological working memory, whereas their performance levels in tasks of visuospatial working memory were on par with the hearing children. A majority of the children with CI demonstrated reading skills within the normal range for hearing children, both for decoding and reading comprehension. The relations between demographic factors and cognitive skills varied somewhat between the studies. The patterns of result are discussed with reference to contemporary theories of working memory, phonological skills, and lexical access.