Peter C. M. Molenaar, PhD , is a professor of human development in the Department of Human Development and Family Studies at The Pennsylvania State University, State College. The general theme of his work involves the application of mathematical theories in the following fields of research: singularity theory (in particular, catastrophe theory) to study developmental stage transitions, nonlinear signal analysis techniques to map theoretical models of cognitive information processing onto dynamically interacting neural sources, ergodic theory to study the relationships between intraindividual (idiographic) analyses and interindividual (nomothetic) analyses of psychological processes, advanced multivariate analysis techniques in quantitative genetics and developmental psychology, adaptive resonance theory neural networks to study the effects of nonlinear epigenetic processes, and computational control techniques to optimally guide developmental psychological processes and disease processes of individual subjects in real time. Karl M. Newell, PhD , is the Marie Underhill Noll Chair of Human Performance and head of the Department of Kinesiology at The Pennsylvania State University, State College. Dr. Newell's research interests lie in the area of human movement in general and motor learning and control specifically.

His research focuses on the coordination, control, and skill of normal and abnormal human movement across the life span; developmental disabilities and motor skills; and the influence of drug and exercise on movement control. One of the specific themes of his research is the study of variability in human movement and posture, with specific reference to the onset of aging and Parkinson's disease. His other major research theme is processes of change in motor learning and development--the focus of this book.