The Effects of Working Memory Capacity on Language Performance in Children with Cochlear Implants

Cho, Eung Kyung; Sung, Jee Eun; Sim, Hyun Sub

ORIGINAL ARTICLE

Commun Sci Disord. 2012;17(1): 79-91.

Eung Kyung Cho^` , Jee Eun Sung^` , and Hyun Sub Sim^`

조응경(Eung Kyung Cho)| 성지은(Jee Eun Sung)| 심현섭(Hyun Sub Sim)

ABSTRACT

Background & Objectives
Working memory capacity (WMC) has received considerable attention as an underlying cognitive mechanism that may account for individual differences in language skills in children with cochlear implants. The purpose of the current study was to investigate which variable significantly predicted differences in performance on a receptive vocabulary test and a sentence comprehension task among age of the cochlear implant, chronological age, duration of usage of cochlear implant, and WMC. In addition, the study examined whether there were significant differences between high and low WMC groups in the two language tests when the age of the cochlear implant, duration of usage of cochlear implant, and chronological age were statistically controlled.
Methods
Twenty prelingual and congenital deaf children between the ages of 7 and 9 years, who received cochlear implantation, participated in the study. The language skills were assessed using standardized tests such as the Receptive and Expressive Vocabulary Test (REVT) and Korean Oral Syntax Expression Comprehension Test (KOSECT). WMC was measured using word forward/backward pointing span tasks. The average of the results of the two span tasks was used as an index of WMC.
Results
The results from the stepwise multiple regression analyses revealed that the WMC was a significant predictor of score on both language tests. The results of ANCOVA showed that the high WMC group showed significantly better performance on the KOSECT than the low WMC group, whereas the group differences were negligible in the REVT.
Discussion & Conclusion
The current results suggested that WMC serves as an underlying cognitive mechanism responsible for individual differences in language performance in children with cochlear implants. The effects of WMC emerged more evidently in a test with greater cognitive load such as a syntactic comprehension test compared to the receptive vocabulary test, given that the high and low WMC group differences were the greatest in the sentence comprehension test.