Browsing by Author "Podd, John"

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    The Bewildered Brain: Asymmetric Brain Activity as a Source of Cognitive Impairment in Depression
    (Massey University, 2011) Campbell, Kathryn; Hill, Stephen; Podd, John
    Individuals with depression commonly complain about cognitive deficits such as memory loss and poor decision making ability (Lahr, Beblo, & Hartje, 2007). However, despite considerable research, no single profile of cognitive deficits in depression has emerged (Ravnkilde et al., 2002). This may be a result of heterogeneity within the diagnostic category of depression. While typically diagnosed as a single disorder, the symptoms of depression may stem from different neurobiological causes leading to different profiles of cognitive deficits. Shenal, Harrison, and Demaree (2003) theorised that subtypes of depression could arise from dysfunctional brain activity in each of the quadrants of the brain (right frontal, left frontal, right posterior, and left posterior). For example, reduced left frontal activity in depression may be associated with impairments in tasks reliant on left frontal regions. Little research has directly investigated the possible link between variability in cognitive deficits and different patterns of dysfunctional brain activity in depression. The current paper reviews evidence for this link by describing depressed individuals’ performance on lateralised cognitive tasks, and discusses possibilities for future research.
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    Into the Void: The Gap Between N-Back and Complex Span Tasks Suggests Inadequacies in Current Models of Working Memory
    (School of Psychology, Massey University, 2012) Campbell, Kathryn; HIll, Stephen; Podd, John
    The tasks used to assess working memory are a highly contentious issue in cognitive psychology. Previous research has found a weak relationship between two key types of working memory tasks: N-Back and Complex Span. This is commonly interpreted as evidence that one or both tasks possess poor construct validity. However, this finding may be a result of assessing different modalities of working memory. The current pilot study aimed to clarify the differences between the two tasks by assessing performance on each within the same modality. A spatial and verbal version of each task was used. Although, theoretically, these tasks assess the same construct, the pilot data revealed low correlations between them. This suggests that the current models of working memory may be inadequate, or that unidentified differences between the tasks may be influencing the results. Due to their widespread use and applications, it is important to better understand models of working memory and develop improved tasks.