Date of Award

Spring 1-1-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology & Neuroscience

First Advisor

Alice F. Healy

Second Advisor

David E. Sherwood

Third Advisor

Matt Jones

Abstract

Research on the focus of attention (FOA) has been ongoing since initial experiments over 15 years ago (see Wulf, 2007a; 2007b). Since that time, research on the FOA has evolved considerably and experimental data has revealed physiological changes underlying behavioral effects of attention. These experimental developments integrate the FOA with other robust findings in motor learning and control (e.g., choking under pressure and implicit learning). This dissertation investigates how an external FOA (e.g., on the goal of a movement) leads to better performance than an internal FOA (e.g., on the body's own movement). Previous research has measured movement outcomes (e.g., accuracy) but not the quality of movement itself (e.g., neuromuscular efficiency, movement variability, movement kinematics). Thus, the current experiments use biomechanical analysis and surface electromyography to explore the role of attention in coordinating movement at the neuromuscular level up to the level of the movement outcome. Data from five experimental studies in this dissertation suggest that attention changes the control structure of the motor system: an external focus of attention reduces variation in the nominal, goal-dimension of the task, whereas an internal focus of attention reduces variation in the pattern of the movement itself (at the expense of task performance; Chapter 4). Underlying the effects of an internal focus of attention are increases in cocontraction of the muscles around a given joint (Chapters 2 and 3). Increasing mechanical impedance in the limb by increasing cocontraction is useful for reducing variability in the movement pattern, but has ancillary consequences of reducing movement efficiency and, often, effectiveness. Furthermore, the FOA appears to affect the performance of learned motor skills rather than the rate of learning itself (Chapter 5). These findings suggest significant expansion of current theories on the focus of attention in order to predict these physiological changes that mediate the attention-performance relationship. A neurophysiological framework for the role of attention in motor control is present in Chapter 6, based on these findings. This framework posits that an internal focus of attention invokes motor control structures that were active early in the learning process (e.g., dorsolateral prefrontal cortex) impairing coordination, efficiency, and effectiveness.

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