Speed of Information Processing and Verbal Working Memory in Children and Adolescents With Cochlear Implants.

BACKGROUND: Verbal working memory delays are found in many deaf children with cochlear implants compared with normal-hearing peers, but the factors contributing to these delays are not well understood. This study investigated differences between cochlear implant users and normal-hearing peers in memory scanning speed during a challenging verbal working memory task. To better understand variability in verbal working memory capacity within each sample, associations between memory scanning speed, speech recognition, and language were also investigated. METHODS: Twenty-five prelingually deaf, early implanted children (age, 8-17 yr) with cochlear implants and 25 normal-hearing peers completed the Wechsler Intelligence Scale for Children, Fifth Edition, Letter-Number Sequencing (LNS) working memory task. Timing measures were made for response latency and average pause duration between letters/numbers recalled during the task. Participants also completed measures of speech recognition, vocabulary, and language comprehension. RESULTS: Children with cochlear implants had longer pause durations than normal-hearing peers during three-span LNS sequences, but the groups did not differ in response latencies or in pause durations during two-span LNS sequences. In the sample of cochlear implant users, poorer speech recognition was correlated with longer pause durations during two-span sequences, whereas poorer vocabulary and weaker language comprehension were correlated with longer response latencies during two-span sequences. Response latencies and pause durations were unrelated to language in the normal-hearing sample. CONCLUSION: Children with cochlear implants have slower verbal working memory scanning speed than children with normal hearing. More robust phonological-lexical representations of language in memory may facilitate faster memory scanning speed and better working memory in cochlear implant users.

Verbal Fluency in Prelingually Deaf, Early Implanted Children and Adolescents With Cochlear Implants.

PURPOSE: Verbal fluency tasks assess the ability to quickly and efficiently retrieve words from the mental lexicon by requiring subjects to rapidly generate words within a phonological or semantic category. This study investigated differences between cochlear implant users and normal-hearing peers in the clustering and time course of word retrieval during phonological and semantic verbal fluency tasks. METHOD: Twenty-eight children and adolescents (aged 9-17 years) with cochlear implants and 33 normal-hearing peers completed measures of verbal fluency, nonverbal intelligence, speech perception, and verbal short-term/working memory. Phonological and semantic verbal fluency tests were scored for total words generated, words generated in each 10-s interval of the 1-min task, latency to first word generated, number of word clusters, average cluster size, and number of word/cluster switches. RESULTS: Children and adolescents with cochlear implants generated fewer words than normal-hearing peers throughout the entire 60-s time interval of the phonological and semantic fluency tasks. Cochlear implant users also had slower start latency times and produced fewer clusters and switches than normal-hearing peers during the phonological fluency task. Speech perception and verbal working memory scores were more strongly associated with verbal fluency scores in children and adolescents with cochlear implants than in normal-hearing peers. CONCLUSIONS: Cochlear implant users show poorer phonological and semantic verbal fluency than normal-hearing peers, and their verbal fluency is significantly associated with speech perception and verbal working memory. These findings suggest deficits in fluent retrieval of phonological and semantic information from long-term lexical memory in cochlear implant users.