title: Working memory in Farsi-speaking children with normal development and cochlear implant.
abstract: OBJECTIVE
  Working memory has an important role in language acquisition and development of cognition skills. The ability of encoding, storage and retrieval of phonological codes, as activities of working memory, acquired by audition sense. Children with cochlear implant experience a period that they are not able to perceive sounds. In order to assess the effect of hearing on working memory, we investigated working memory as a cognition skill in children with normal development and cochlear implant.
  
  
  METHODS
  Fifty students with normal hearing and 50 students with cochlear implant aged 5-7 years participated in this study. Children educated in the preschool, the first and second grades. Children with normal development were matched based on age, gender, and grade of education with cochlear implant. Two components of working memory including phonological loop and central executive were compared between two groups. Phonological loop assessed by nonword repetition task and forward digit span. To assess central executive component backward digit span was used. The developmental trend was studied in children with normal development and cochlear implant as well. The effect of age at implantation in children with cochlear implants on components of working memory was investigated.
  
  
  RESULTS
  There are significant differences between children with normal development and cochlear implant in all tasks that assess working memory (p < 0.001). The children's age at implantation was negatively correlated with all tasks (p < 0.001). In contrast, duration of usage of cochlear implant set was positively correlated with all tasks (p < 0.001). The comparison of working memory between different grades showed significant differences both in children with normal development and in children with cochlear implant (p < 0.05).
  
  
  CONCLUSIONS
  These results implied that children with cochlear implant may experience difficulties in working memory. Therefore, these children have problems in encoding, practicing, and repeating phonological units. The results also suggested working memory develops when the child grows up. In cochlear implant children, with decreasing age at implantation and increasing their experience in perceiving sound, working memory skills improved.
authors.affiliation: School of Rehabilitation, Tehran University of Medical Sciences, Iran. Electronic address: Soleymaniz@sina.tums.ac.ir.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Soleymani
authors.affiliation: School of Rehabilitation, Tehran University of Medical Sciences, Iran.
authors.forename: Meysam
authors.initials: M
authors.lastname: Amidfar
authors.affiliation: School of Rehabilitation, Tehran University of Medical Sciences, Iran.
authors.forename: Hooshang
authors.initials: H
authors.lastname: Dadgar
authors.affiliation: School of Rehabilitation, Tehran University of Medical Sciences, Iran.
authors.forename: Shohre
authors.initials: S
authors.lastname: Jalaie
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D018912:Arabs; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D019929:Cochlear Implantation; D003054:Cochlear Implants; D015331:Cohort Studies; D006801:Humans; D007492:Iran; D007802:Language; D007804:Language Development; D007807:Language Tests; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D011446:Prospective Studies; D012016:Reference Values; D013065:Speech Intelligibility; D013647:Task Performance and Analysis
keywords: Age at implantation; Cochlear implant; Development; Farsi-speaking children; Working memory