This book is a comprehensive examination of research and theoretical perspectives on movement variability and motor control. The text reviews traditional perspectives - which view movement variability as noise or error - and moves on to consider dynamical systems approaches to movement control, which view variability as an index of movement fluctuations. Written by leading experts in motor control, "Variability and Motor Control" provides readers with valuable information on the importance of variability in the theoretical inquiry into motor control, skill acquisition and movement impairment; the use of estimated variability as a movement parameter in empirical studies of motor control; and current developments of new dynamical systems approaches to variability and motor control. Part I provides a summary of the characteristics of force variability and examines several different deterministic models, including impulse-variability models of multi-joint movement control. In Part II the variability and movement speed-accuracy trade-off are examined from four different deterministic perspectives.
New and diverse dynamical systems approaches to variability and motor control are covered in Part III. The contributors discuss how processes of self-organization can be applied to motor control, summarize and apply the general dynamical principles developed for continuous tasks to the stability of discrete bimanual actions, and examine interlimb co-ordination and methodologies of observing variability. Finally, Part IV reveals how describing and understanding variability can further the knowledge of movement impairment. Through the use of both dynamical systems and deterministic approaches, the contributors examine the role of variability in understanding performance deficits, limb apraxia and movement stereotypy. Designed as a graduate text and reference for students and scholars of motor control and learning, this text should als be of interest to experimental psychologists, ergonomists, and industrial/human factors specialists.