Language processing fluency and verbal working memory in prelingually deaf long-term cochlear implant users: A pilot study

OBJECTIVE: Verbal working memory (WM) is more strongly correlated with spoken language skills in prelingually deaf, early-implanted cochlear implant (CI) users than in normal-hearing (NH) peers, suggesting that CI users access WM in order to support and compensate for their slower, more effortful spoken language processing. This pilot study tested the feasibility and validity of a dual-task method for establishing the causal role of WM in basic language processing (lexical access speed) in samples of 9 CI users (ages 8-26 years) and 9 NH peers. METHODS: Participants completed tests of lexical access speed (rapid automatized picture naming test and lexical decision test) under two administration conditions: a standard condition and a dual-task WM condition requiring participants to hold numerals in WM during completion of the lexical access speed tests. RESULTS: CI users showed more dual-task interference (decline in speed during the WM condition compared to the standard condition) than NH peers, indicating that their lexical access speed was more dependent on engagement of WM resources. Furthermore, dual-task interference scores were significantly correlated with several measures of speed-based executive functioning (EF), consistent with the hypothesis that the dual-task method reflects the involvement of EF in language processing. CONCLUSION: These pilot study results support the feasibility and validity of the dual-task WM method for investigating the influence of WM in the basic language processing of CI users. Preliminary findings indicate that CI users are more dependent on the use of WM as a compensatory strategy during slow-effortful basic language processing than NH peers