The transition to reaching: mapping intention and intrinsic dynamics.

The onset of directed reaching demarks the emergence of a qualitatively new skill. In this study we asked how intentional reaching arises from infants' ongoing, intrinsic movement dynamics, and how first reaches become successively adapted to the task. We observed 4 infants weekly in a standard reaching task and identified the week of first arm-extended reach, and the 2 weeks before and after onset. The infants first reached at ages ranging from 12 to 22 weeks, and they used different strategies to get the toy. 2 infants, whose spontaneous movements were large and vigorous, damped down their fast, forceful movements. The 2 quieter infants generated faster and more energetic movements to lift their arms. The infants modulated reaches in task-appropriate ways in the weeks following onset. Reaching emerges when infants can intentionally adjust the force and compliance of the arm, often using muscle coactivation. These results suggest that the infant central nervous system does not contain programs that detail hand trajectory, joint coordination, and muscle activation patterns. Rather, these patterns are the consequences of the natural dynamics of the system and the active exploration of the match between those dynamics and the task.

[1]  R. Held,et al.  OBSERVATIONS ON THE DEVELOPMENT OF VISUALLY-DIRECTED REACHING. , 1964, Child development.

[2]  T. Bower,et al.  The coordination of visual and tactual input in infants , 1970 .

[3]  J. Piaget,et al.  The Origins of Intelligence in Children , 1971 .

[4]  J. Bruner,et al.  Visually Preadapted Constituents of Manipulatory Action , 1972, Perception.

[5]  J. Bruner Organization of early skilled action. , 1973, Child development.

[6]  J. S. Thomas,et al.  The Continuity of Movements , 1973 .

[7]  E. Bizzi,et al.  Processes controlling arm movements in monkeys. , 1978, Science.

[8]  J C Houk,et al.  Regulation of stiffness by skeletomotor reflexes. , 1979, Annual review of physiology.

[9]  P. N. Kugler,et al.  1 On the Concept of Coordinative Structures as Dissipative Structures: I. Theoretical Lines of Convergence* , 1980 .

[10]  J. Cooke 11 The Organization of Simple, Skilled Movements , 1980 .

[11]  G. Stelmach,et al.  Tutorials in Motor Behavior , 1980 .

[12]  A. G. Feldman Superposition of motor programs—I. Rhythmic forearm movements in man , 1980, Neuroscience.

[13]  C. Hofsten Eye–hand coordination in the newborn. , 1982 .

[14]  E. Thelen,et al.  The organization of spontaneous leg movements in newborn infants. , 1983, Journal of motor behavior.

[15]  E Thelen,et al.  Shifting patterns of bilateral coordination and lateral dominance in the leg movements of young infants. , 1983, Developmental psychobiology.

[16]  C. Trevarthen,et al.  Chapter IIIa How Control of Movement Develops , 1984 .

[17]  N. A. Bernshteĭn,et al.  Human motor actions : Bernstein reassessed , 1984 .

[18]  N. Hogan An organizing principle for a class of voluntary movements , 1984, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[19]  C. Hofsten Developmental changes in the organization of prereaching movements , 1984 .

[20]  J. F. Soechting,et al.  Psychophysical determination of coordinate representation of human arm orientation , 1984, Neuroscience.

[21]  H. Gainer,et al.  Neurophysin in the hypothalamo-neurohypophysial system. I. Production and characterization of monoclonal antibodies , 1985, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[22]  E. Bushnell The decline of visually guided reaching during infancy , 1985 .

[23]  O. I. Fukson,et al.  Adaptability of innate motor patterns and motor control mechanisms , 1986, Behavioral and Brain Sciences.

[24]  G. Gottlieb,et al.  STRETCH REFLEXES OF THE NORMAL INFANT , 1986, Developmental medicine and child neurology.

[25]  Esther Thelen,et al.  Bilateral coordination in human infants: stepping on a split-belt treadmill. , 1987 .

[26]  E. Thelen,et al.  The dynamic nature of early coordination: Evidence from bilateral leg movements in young infants. , 1987 .

[27]  Esther Thelen,et al.  Development of early expressive and communicative action: Reinterpreting the evidence from a dynamic systems perspective. , 1987 .

[28]  Elliot Saltzman,et al.  Skilled actions: a task-dynamic approach. , 1987, Psychological review.

[29]  E. Bizzi,et al.  Controlling multijoint motor behavior. , 1987, Exercise and sport sciences reviews.

[30]  Geoffrey P. Bingham,et al.  Task-specific devices and the perceptual bottleneck☆ , 1988 .

[31]  M. Jeannerod The neural and behavioural organization of goal-directed movements , 1990, Psychological Medicine.

[32]  E. Gibson Exploratory behavior in the development of perceiving, acting, and the acquiring of knowledge. , 1988 .

[33]  G. Butterworth,et al.  Hand-mouth coordination in the new-born baby , 1988 .

[34]  G. Gottlieb,et al.  Strategies for the control of voluntary movements with one mechanical degree of freedom , 1989, Behavioral and Brain Sciences.

[35]  R. Schmidt,et al.  Changes in limb dynamics during the practice of rapid arm movements. , 1989, Journal of biomechanics.

[36]  S. Grossberg,et al.  Motor Skill Development and Neural Networks for Position Code Invariance under Speed and Compliance Rescaling , 1990 .

[37]  E. Thelen,et al.  Understanding movement control in infants through the analysis of limb intersegmental dynamics. , 1990, Journal of motor behavior.

[38]  Pier-Giorgio Zanone,et al.  Experimental Studies of Behavioral Attractors and Their Evolution with Learning , 1991 .

[39]  E. Thelen,et al.  Hidden skills: a dynamic systems analysis of treadmill stepping during the first year. , 1991, Monographs of the Society for Research in Child Development.

[40]  R. Zernicke,et al.  Mass, center of mass, and moment of inertia estimates for infant limb segments. , 1992, Journal of biomechanics.

[41]  R. K. Clifton,et al.  Is visually guided reaching in early infancy a myth? , 1993, Child development.

[42]  G. Edelman,et al.  Solving Bernstein's problem: a proposal for the development of coordinated movement by selection. , 1993, Child development.

[43]  R. F. Zernicke,et al.  Adaptive Dynamics of the Leg Movement Patterns of Human Infants: II. Treadmill stepping in Infants and Adults. , 1994, Journal of motor behavior.