Task switching is an important aspect of cognitive control and understanding its underlying mechanisms is the focus of considerable research. In this paper, we contrast two different kinds of task switching paradigms and provide evidence that different cognitive mechanisms underlie switching behavior depending on whether the switch is between sets of rules (rule switch) or sets of features presented simultaneously (perceptual switch). In two experiments, we demonstrate that behavioral effects (Experiment 1) and neural recruitment (Experiment 2) vary with the type of switch performed. While perceptual switch costs occurred when the alternative feature set was physically present, rule switch costs were observed even in their absence. Rule switching was also characterized by larger target repetition effects and by greater engagement of the dorsolateral prefrontal cortex. In contrast, perceptual switching was associated with greater recruitment of the parietal cortex. These results provide strong evidence for multiple forms of switching and suggest the limitations of generalizing results across shift types.
KeywordsExecutive function; cognitive control; dorsolateral prefrontal cortex; superior parietal cortex; fMRI The ability to switch tasks rapidly is important for responding flexibly in a changing environment (Miller & Cohen, 2001). Both behavioral and neuroscientific investigators have sought to understand how people disengage from one task in order to undertake another (see Monsell, 2003, for a review). In this set of experiments, we seek to understand the behavioral and neural consequences associated with different forms of task switching. Specifically, we examine whether there are qualitative differences in the cognitive mechanisms used to switch between tasks that require the reorienting of visuospatial attention (e.g., to what or where should I attend?) and switches that involve the ability to deal with changing goal-related information such as rules (e.g., what should I do?). We propose that the "task" used to investigate task switching (or "set" in set shifting) has important implications for understanding the nature of © 2008 Elsevier Ltd. All rights reserved.Corresponding address: Dr. Susan Ravizza, Dept. of Psychology, Michigan State University, East Lansing, MI, 48824 Email: E-mail: ravizzas@msu.edu Phone: 517−432−3366. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Author ManuscriptNeuropsychologia. Author manuscript; available in PMC 2009 October 1.
Published in final edited form as:Neuropsychologia.
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