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Use of Verbal Mediation to Facilitate Working Memory Performance in Persons with Aphasia Open Access

Introduction: We use language to communicate with one another and with ourselves. Using self-directed inner language to guide our behavior is referred to as verbal mediation. The impact of aphasia on communication between people has been widely studied, while the impact of aphasia on verbal mediation has not. This study investigated the relationship between lexical access and performance on a working memory task (n-back) to determine if Persons with Aphasia (PWA) use intact word retrieval (verbal mediation) to support working memory. An articulatory suppression condition was also conducted to determine if disruption of the working memory phonological loop impairs the use of verbal mediation. Method: Four PWA and four Neurologically Intact (NI) participants completed n-back tasks varying in load (n=0, 1, 2) and stimulus type (readily nameable/ high frequency objects, unnameable/ low frequency objects, blocks) under both baseline and articulatory suppression conditions. Data analysis explored the impact of these variables within and across participants and groups. Results: The PWA group performed significantly worse than the NI group for nine n-back tasks. In five instances where a significant difference was found among the load levels, the significant difference was in the direction of n=0 > n=2. None of the comparisons among the stimulus types or between the conditions was significant. Comparisons between individual PWA scores and the mean NI scores yielded 23 significant differences, with PWA performing significantly worse. Discussion: The PWA group presented with decreased WM capacity when compared to the NI group, particularly for 1-back tasks. For both groups, WM capacity was impaired in a predominantly load-dependent manner, with significant differences in the direction of n=0 > n=2. Overt naming ability did not align with WM performance. Implementation of the articulatory suppression condition did not impact WM performance. A WM deficit may contribute to language-processing impairments in the PWA group. If PWA are attempting to use verbal mediation to guide their thoughts and behavior, their ability to use covert language may be impacted by concomitant WM deficits and degraded performance associated with subtle changes in processing load. Intact word retrieval may not support the use of verbal mediation to facilitate working memory performance; however, PWA may employ the visuospatial sketchpad to support WM when lexical retrieval fails. Results also align with anecdotal evidence from PWA that they have access to inner language even when they have difficulty communicating with others.

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