DYNAMIC SYSTEMS THEORIES 258 Intellectual Heritage: Developmental Process 259 Lessons from Embryology: Form from a Formless Egg 260 The Mountain Stream Metaphor 263 Epigenesis in Developmental Psychobiology 263 Contextual and Ecological Theorists 266 An Introduction to Dynamics Systems Thinking 271 Development from a Dynamic Systems Perspective 276 Bimanual Coordination 297 What Is Skill? 298 S...

Dexterity, defined as the skillful manipulation of the hands, is now amenable to physiological investigation. Two topics are discussed here: grasping (i.e., hand-object coupling) and bimanual coordination. Dexterity depends on powerful, distributed neural networks and is particularly vulnerable to brain lesions. A knowledge of physiological mechanisms is needed to deal with these neurological p...

Intra- and interpersonal interlimb coordination of pendulums swung from the wrist was investigated. For both kinds of coordination, the steady state and breakdown of bimanual rhythmic coordination as indexed by the time series of the relative phase angle phi were studied under the manipulation of coordination mode, frequency of oscillation, and the difference in the eigenfrequencies (preferred ...

Coordination of the hand grip (G; acting normally to the grasping surface) and load forces (L; acting in parallel) in bimanual static tasks was studied. L symmetry (either the magnitude or direction) and frequency were manipulated in healthy participants (N = 14). More complex tasks (i.e., the higher frequency and/or asymmetric ones) revealed expected deterioration in both the task performance ...