A central question in motor development is the extent to which neural maturation and experience contribute to development. In the past researchers believed that motor development was simply the result of maturation of the nervous system directed by biological processes. Recently experimental results have gradually redirected attention to the influence of experience and learning. Our research employs both experimental and theoretical methods to show how experience interacts with neural maturation as human infants learn to reach during the first two years of life. Our experimental work focuses on the development of reaching in infants from the ages of eight weeks to two years. Infants are brought into the laboratory and presented with naturalistic reaching tasks. Data are acquired about the positions of the hand and of the joints of the arm during reaches.

Neil E. Berthier Cognitive and Motor Development in Human Infants We compute kinematic measures such as the speed of the hand, the aperture of grasps, the direction of the hand movement in space, and the accuracy of movement that inform us about the goals of the infant and the motor strategies that infants use to meet their goals. Key interests of this work are to determine how infants plan and execute reaching movements and what aspects of the task are important in an infant's selection of motor strategy. Our results show that even young infants are sensitive to the demands of the task and to reduced sensory information about the location of the goal objects in space.

Our theoretical work has produced a mathematical model of the development of reaching. The model is based on ideas from theories of learning in connectionist networks, results from adult reaching studies, and from the hypotheses of workers in motor development. The model suggests that infants are constantly learning about the current capabilities of their motor systems and adapting reaching strategies to accord with their current level of motor control. The model characterizes infants not as passive individuals who simply wait for motor abilities to come on-line through neural maturation but as individuals who are constantly exploring their own capabilities and matching their motor strategies to their current abilities and the reaching task. The model makes precise predictions about the course of motor development that are being tested in the laboratory.   For additional information, please visit my Home Page.

Representative Publications:

 

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Berthier, N.E., Singh, S.P., Barto, A.G., and Houk, J.C. (1993). Distributed representation of limb motor programs in arrays of adjustable pattern generators. J. Cognitive Neurosci 5: 56-78.

Clifton, R.K., Rochat, P., Robin, D.J., and Berthier, N.E. (1994). Multimodal perception in the control of infant reaching. Journal of Experimental Psychology: Human Perception and Performance, 20, 876-886.

Berthier, N.E., Clifton, R.K., Gullipalli, V., McCall, D., and Robin, D. (1996). Visual information and object size in the control of reaching. Journal of Motor Behavior, 28, 187-197.

Berthier, N.E. (1996). Learning to reach: A mathematical model.Developmental Psychology, 32, 811-823.

Robin, D.J., Berthier, N.E., and Clifton, R.K. (1996). Infants' predictive reaching for moving objects in the dark. Developmental Psychology, 32, 824-835.

Berthier, N.E. (1997). Analysis of reaching for stationary and moving objects in the human infant. In: J. Donahoe and V.P Dorsal (Eds.) Neural Network Models of Complex Behavior - Biobehavioral Foundations. North Holland: Amsterdam, 283-301.

Berthier, N.E. & Robin, D.J. (1998). Mid-reach corrections to shifting targets by seven-month-old infants. Journal of Motor Behavior, 30, 290-300.

Berthier, N.E., Clifton, R.K., McCall, D., & Robin, D. (1999). Proximodistal structure of early reaching in human infants. Experimental Brain Research, 127, 259-269.

O'Sullivan, L.P. & Berthier, N.E. (submitted). Visual attention during looking and reaching in 7.5 month-old infants.

Loukopoulos, L., Englebrecht, S. & Berthier, N.E. (2001). Planning of reach-and-grasp movements: Effects of validity and type of object information. Journal of Motor Behavior, 33, 255-264.

Berthier, N.E. (1999). Development of reaching in young infants: Neural and experiential factors. Talk delivered at IXth European Conference on Developmental Psychology, Spetses, Greece.

Berthier, N.E., Bertenthal, B.I., Seaks, J.D., Sylvia, M., Johnson, R., & Clifton, R.K. (2001). Using object knowledge in visual tracking and reaching, Infancy, 2, 257-284.

Berthier, N.E., DeBlois, S., Poirier, C., Novak, M., & Clifton, R.K. (2000). Where's the ball? Two- and three-year-olds reason about unseen events. Developmental Psychology, 36, 394-401

Englebrecht, S.C., Berthier, N.E., & O'Sullivan, L.P. (under revision). The undershoot bias-A stochastic optimal control strategy.

Berthier, N.E., Barto, A.G., and Schlesinger, M. (2000). Learning and dynamics. Proceedings of the NSF DARPA Conference on Learning and Development.

 

 

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