Priming and Executive Control

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How do we control our thoughts and actions? This is a age-old question that penetrates to the heart of studies in mind and behavior. In trying to answer this question, it has been difficult to avoid the invocation of a "homunculus", or controller of the mind that essentially runs the show. The problem with the homunculus is that it sidesteps the fundamental question of control: if the homunculus is controlling the mind, then who or what is controlling the homunculus?With funding from the National Science Foundation, Dr. Logan and his colleagues will tackle the problem of the homunculus. The aim is to develop theory and experimental procedures that allow us to distinguish between thoughts and actions that are controlled voluntarily by a person (top-down control), from those that are controlled by aspects of the environment (bottom-up control). This research will extend prior work funded by NSF on a formal model of control, in which the environment was the only source of causation for thoughts and actions. The success of this model in accounting for human performance was surprising and informative, because it suggested that top-down control was unnecessary to explain behavior that would otherwise appear volitional. The current research will continue to push this idea in the context of experiments in which participants must voluntarily switch between two tasks. Task switching is known to take a toll on performance, but it is debated whether this toll reflects the workings of voluntary control, or more automatic processes of memory. The proposed experiments and models promise to make substantial headway on this debate.