Down Syndrome and Grasping 451 451 Geert J.P. Savelsbergh and John van der Kamp are with the Research Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement Sci- ences at the Vrije Universiteit,Van der Boechorststraat 9, 1081 BT Amsterdam, the Nether- lands. E-mail: <G_J_P_Savelsbergh@fbw.vu.nl>. Walter E. Davis is with the Exercise, Leisure, and Sport Dept. at Kent State University, Kent, Ohio 44242. ADAPTED PHYSICAL ACTIVITY QUARTERLY, 2001, 18, 451-457 © 2001 Human Kinetics Publishers, Inc. Perception-Action Coupling in Grasping of Children With Down Syndrome Geert J.P. Savelsbergh and John van der Kamp Vrije Universiteit, Amsterdam Walter E. Davis Kent State University Twenty-one children with Down syndrome (DS) and 20 without disability, ages 3 to 11 years, completed the experiment in which they were asked to grasp and lift cardboard cubes of different sizes (2.2 to 16.2 cm in width). Three conditions were used: (a) increasing the size from the smallest to the largest cube, (b) decreasing the size from the largest to the smallest, and (c) a random order of sizes. Children with DS were found to have smaller hand sizes in comparison to age-matched children without DS. In addition, the shift from one-handed to two-handed grasping appeared at a smaller cube size for children with DS than for children without DS. However, when the dimen- sionless ratio between object size and hand size was considered, the differ- ences between groups disappeared, indicating that the differences in grasping patterns between children with and without DS can be attributed to differ- ences in body size. The development of grasping has often been studied by using qualitative descriptions (e.g., Connolly & Elliott, 1972; Gesell, 1928; Halverson, 1931). As in studies describing the development of posture and locomotion, grip configura- tions were reported to develop in a regular and orderly sequence. That is, early grasping patterns were described as primitive reflex movements progressing from crude power (whole hand) grasps to grasps using precise index finger-thumb op- position. This latter grasp was considered to represent a “mature” pattern (Connolly, 1973; Halverson, 1931). These grasping patterns were primarily classified on the basis of the anatomical structures involved (cf., Napier, 1962). From this matura- tional perspective, growth or maturation of the nervous system exclusively con- trols the development of grasping patterns. In contrast, proponents of the cognitive approach argued that the production of movement patterns is controlled by so-called