Between-session and within-session intra-individual variability in attention in aphasia
Villard, Sarah Noelle
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It has been shown in previous studies that persons with aphasia (PWA) exhibit deficits in cognitive skills, despite the traditional definition of aphasia as an impairment specifically in language processing. This project provides an in-depth look into one of these cognitive processes: attention. This project views attention from a domain-general perspective and is particularly focused on looking at intra-individual variability (IIV) in attention over time. We begin by presenting a schema of attention and language in aphasia, followed by the results of two experiments that examine the effect of task demands on attention processing, including IIV in performance. The first experiment focuses on the effect of task demands on between-session IIV (BS-IIV) in attention, as well as on group differences between PWA and controls, using purely non-linguistic tasks. Results suggest that PWA exhibit overall higher degrees of BS-IIV in domain-general, attention than do controls. Results also suggest that increased task demands elicit increased BS-IIV in attention in PWA, but not in controls. The second experiment examines the effects of task demands on BS-IIV as well as on within-session IIV (WS-IIV) in attention, as well as group differences between PWA and controls, using both linguistic and non linguistic tasks. Results of this experiment suggest that PWA and controls exhibit similar levels of BS-IIV, but that PWA exhibit higher levels of WS-IIV than do controls. Additionally, both groups show an effect of task demands on both BS-IIV and WS-IIV, such that higher task demands elicit higher levels of both types of IIV. Results also suggest that levels of BS-IIV and WS-IIV may rise even further for PWA when language demands are added to a task. Together, the results of these experiments suggest that PWA experience higher degrees of IIV than controls, and that higher task demands, including the addition of language tasks, increase PWA levels of IIV even more. These findings may have important implications for understanding attention during language therapy, as therapy sessions involve complex demands and require consistent attention over time. Future research should directly examine the relationship between IIV in attention and treatment outcomes in PWA.