Assessing Capacity and Control of Visual Working Memory
Magnotti, John, IV
Type of Degreedissertation
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This paper develops 3 experiments to answer fundamental questions about the independence of storage and control processes in visual working memory (VWM). Results from Experiment 1 showed that executive control processes are invoked even for simple color-change detection tasks using the forced-choice method. Experiment 2 increased the difficulty of the sample-probe comparison in order to assess how high levels of comparison difficulty impact estimates of VWM capacity. Experiment 3 presents a novel modification of the change detection procedure and shows independence between storage and control processes in VWM. Results from these experiments contribute to a better characterization of VWM. A running theme throughout each experiment is that changes to the task at choice time can affect VWM capacity estimates. Rather than support the original view that VWM is a highly robust representation, the current results add to the growing body of literature suggesting the fragility of VWM (e.g., Makovski, & Jiang, 2008; Makovski, Shim, & Jiang, 2006). More unique to the current work is the focus of interference at choice time rather than at encoding or during maintenance. Taken together, these results show the importance of quantifying the joint contribution of each VWM process in order to better understand them individually.