Effects of visual-manual tracking under dual-task conditions on auditory language comprehension and story retelling in persons with aphasia

Background: Two recent studies (McNeil et al., 2004, 2005) evaluated non-brain-injured (N-BI) elderly persons' dual-task performance oil a story retell procedure (SRP) and a visual-manual line-tracking task. Results of both studies demonstrated a unidirectional cost whereby the difficulty of the language task had an effect on tracking performance; however, the difficulty of the tracking task had no effect on language comprehension as indexed by story retelling. Aims: The specific aim of this investigation was to assess the effects of performing a concurrent visual-manual tracking task on the comprehension of stories in persons with aphasia (PWA). Methods & Procedures: The current study evaluated the performance trading in these tasks in PWA using similar dual-task procedures as those employed ill the McNeil et al (2004 2005) studies. Specifically, two tracking difficulty levels were used to assess concurrent costs under a single difficulty level of the SRP. Outcomes & Results: The results of this study replicate, in PWA, the null effect of tracking, difficulty on story retell performance that was found in the two earlier studies in N-BI elderly persons. Contrary to predictions, there was no significant effect of tracking difficulty on story retell performance. There was also no significant difference between story comprehension or visual manual-tracking tasks performed alone or in the competing conditions. Conclusions: The results of this study do not support the hypothesis that a deficit in allocating processing resources in PWA would result in a concurrent cost of tracking difficulty on story comprehension. The results are discussed relative to the limitations of the story retell procedure for indexing potential dual-task effects and relative to the possible structure of the shared cognitive architecture used in these specific dual-tasks.