Visual and Auditory Word Memory in Postlingual Cochlear Implanted as Compared to Normal Hearing Older Adults

Background: In recent years, the association between hearing impairments and cognitive abilities has been receiving increasing attention. Previously, we found that prelingual cochlear implant (CI) recipients showed lower auditory word memory ability relative to normal hearing (NH) group while their visual word memory was comparable.

Objective: The present study evaluated auditory and visual word learning strategies among older postlingual CI group as compared to older NH (ONH) adults.

Methods: 25 older adults (age>60 years) (CI- 11, ONH-14). All participants showed intact cognitive abilities (MOCA >26). All CI users showed good open-set speech perception results (mono syllabic > 50%, di-syllabic >80%). Participants performed two verbal learning tasks, in which words were learned by vocal production (saying aloud) or by no-production (silent reading or listening), followed by a free recall test (a Production Effect-PE paradigm). These tasks were performed via the auditory and the visual modalities.

Results: Both groups (ONH and postlingual CI) showed a production benefit with visual and auditory presentations (higher recall rates for vocalized than silently read words). The size of the PE was larger in the visual modality in compared to the auditory modality for both groups. Comparing these results to a previous study with prelingual young CI users revealed that while prelingual CI users show reduced auditory word learning as compared to NH, postlingual CI users show comparable auditory strategies as NH older adults.

Conclusions: The results support the use of vocal production as a memory strategy (via the auditory and the visual modalities) in older adults. Such technique may be easily used in everyday situations, e.g. following a medication schedule, memorizing directions. The similarity between ONH and older postlingual CI may suggest that when deafness occurs after the completion of language acquisition, the participants use similar long-term word learning strategies, hinting on comparable cognitive abilities.