Browsing by Author "Allen, Corinne"

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    Inhibitory control mechanisms and their role in task switching: A multi-methodological approach
    (2013-05-13) Allen, Corinne; Martin, Randi C.; Schnur, Tatiana T.; Oswald, Frederick L.; Kemmer, Suzanne E.; Basak, Chandramallika
    Executive control allows us to ignore distraction and switch between tasks in a flexible, yet organized fashion. While a hallmark of controlled behavior, distinctions among executive control processes are not thoroughly agreed upon. The present work explored the organization of two of these executive control processes, inhibition and shifting, and their relationship to each other. There were two primary goals. The first goal was to investigate the distinction among inhibitory control processes, as “inhibition” has oftentimes been considered a unitary construct. For example, there is evidence that response-distractor inhibition, which involves resolving interference from dominant responses or distractors in the external environment, is different from resistance to proactive interference (PI), which involves overcoming interference from previously relevant representations in memory. Using aging, neuropsychology, and individual differences methodologies, I investigated the unity and diversity of inhibitory control mechanisms. The healthy aging and neuropsychological evidence supported a distinction between response-distractor inhibition and resistance to proactive interference. However, when controlling for processing speed, the individual differences work suggested a need for further specification, as only a subset of these tasks emerged in the single factor model that provided the best fit to the data. The second goal was to explore how inhibitory control processes interact with task switching, as some theoretical accounts of task switching have suggested that switch costs result from the need to overcome interference from the previously relevant task. Inconsistent with these theories, I found little relation between inhibitory control and measures of global and local task switching, and instead, working memory served as the best predictor of these shifting measures. In contrast, inhibitory control was related to the backward inhibition abilities of older adults. These findings are discussed within a theory of working memory that accounts for the patterns of results found across the different methodologies.
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    Task switching and short-term retention: The role of memory load in task switching performance
    (2010) Allen, Corinne; Martin, Randi C.
    Shifting, which is the process of switching task sets between two or more tasks, incurs a cost: participants are slower and more error prone when a switch is required, relative to when the same task is performed in a sequential manner. Recent research in our lab has found a performance dissociation between two task switching paradigms in ML, a patient with reduced short-term memory (STM) capacity. The present study investigates the hypothesis that this dissociation is a result of memory load differences between the two shifting paradigms. We tested this hypothesis by measuring shifting abilities in patients with phonological and semantic short-term memory deficits, as well as age-matched controls under standard and articulatory suppression conditions. The results suggest that task-related memory demands impair the shifting performance of patients with STM deficits, and that phonological (but not semantic) retention contributes to shifting as task requirements increase.