Mastering Reaching and Grasping: The Development of Manual Skills in Infancy

This chapter deals with the development of reaching and grasping during the 1st year of life, when infants start to reach and grasp objects successfully and major changes in the organization of the manual movements accompany this event.

Abstract

This chapter deals with the development of reaching and grasping during the 1st year of life. As the maturation of the nervous system imposes the most severe constraints on this development, an attempt is first made to summarize what is known about the motor pathways and the sensorimotor systems involved in manual development. The chapter then sketches the presumed major steps in the manual development of the human infant. Visual control of arm movements is already present in newborn infants, but the arm and the hand are synergistically coupled in these movements. As the arm extends, the hand opens and vice versa. This synergy is broken up at about 2 months as infants start to fist the hand vigorously as the arm extends. That pattern gives way to a more functional one in which the hand opens up during arm extension in preparation for grasping an object. Around 4 months of age, infants start to reach and grasp objects successfully. Major changes in the organization of the manual movements accompany this event. Vision takes a more prominent role in the control of hand movements as the infant gains ability to monitor the hand relative to a target. The major change in manual control during the second half of the 1st year of life is the appearance of differentiated finger movements and the