![]() ![]() Each of these studies set out to test theoretical claims about WM by comparing the brain activation patterns associated with retrieval of items from different serial positions in a list, an idea based on earlier behavioral research ( Postman and Phillips, 1965 Glanzer and Cunitz, 1966). Using both behavioral and neuroimaging (fMRI) methods, we test the hypothesis that subtle features of the tasks used to probe WM function (e.g., task instructions and response requirements) can lead to important performance differences (e.g., which item in a list is remembered the quickest), fundamental changes in the pattern of brain activity evoked by the WM task, and ultimately, to different conclusions about the FOA and its involvement in WM.Ī set of recent fMRI studies inform our approach ( Talmi et al., 2005 Nee and Jonides, 2008, 2011 Öztekin et al., 2009, 2010). The present paper explores one explanation for divergent conclusions about the architecture and capacity of WM, and concentrates on the contributions of the “focus of attention” (FOA, or the most immediate state of WM) to WM capacity ( Cowan, 1995). While researchers generally agree on the existence of such capacity limits, ongoing debate surrounds the precise structure and function of human memory, including the specific properties and capacity limits of WM ( Miyake and Shah, 1999 Jonides et al., 2008). Findings are discussed as they inform models of the structure and capacity of WM.Ī wide variety of research suggests strict limits on the mind's ability to maintain and manipulate information over the short term-an ability often referred to as working memory (WM e.g., Luck and Vogel, 1997 Cowan, 2001 McElree, 2006). In sum, two experiments demonstrate that the behavioral and neural signatures of WM, specifically related to primacy and recency effects, are dependent on task-demands. ![]() However, presence of the primacy item in the probe significantly influenced activity in frontal lobe brain regions linked to active maintenance, but the location and direction of activation changes varied as a function of task instructions. In contrast to past studies, fMRI contrasts revealed no brain regions where activity was significantly altered by the presence of recency items in the probe, for either task condition. Behavioral results from two experiments confirmed this prediction. Analyses tested the prediction that a WM task emphasizing later items in a list (judgment of recency) would encourage exaggerated recency effects and attenuated primacy effects, while a task emphasizing earlier items (judgment of primacy) would encourage exaggerated primacy effects and attenuated recency effects. Two experiments varied task-demands by requiring participants to remember lists of letters and to then respond to a subsequent two-item probe by indicating either the item that was presented later in the list (judgment of recency) or the item was presented earlier (judgment of primacy). The present study investigates whether a pattern of larger recency effects and smaller primacy effects reported in previous working memory studies is specific to task conditions used in those studies, or generalizes across manipulations of task-demand. Ongoing debate surrounds the capacity and characteristics of the focus of attention. ![]() 2Department of Psychology, Princeton University, Princeton, NJ, USA.1Department of Psychology, Temple University, Philadelphia, PA, USA. ![]()
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