ABSTRACT
Children born with Down syndrome possess three 21st chromosomes in every cell of their body (cf. mosaicism). The syndrome is present in approximately one in every 800 live births, and is associated with a number of anatomical and physiological abnormalities that impact on both physical and cognitive development. In this chapter, we review studies from our own laboratories and elsewhere designed to examine perceptual-motor behaviour in this unique group of people. Our focus is on the control of goal-directed upper limb movements. Of interest is determining the similarities and differences between persons with Down syndrome and normally developing children, and what the implications of any differences are for understanding perceptual-motor behaviour in different movement contexts. It is well known that children and young adults with Down syndrome require more time to both initiate and complete simple, goal-directed upper limb movements than nondisabled persons of a similar chronological age (see Anson and Mawston, 2000, and Welsh and Elliott, 2000 for a review). There is less agreement as to whether a disadvantage, or at least a difference, exists when children with Down syndrome are compared to other persons of a similar developmental age. The answer to this question, as well as a description of any developmental differences that might exist between children with Down syndrome and normally developing children, provides the basis for understanding how persons with Down syndrome perform simple reaching and aiming movements such as the ones involved in preparing or eating a meal, using a keyboard, and performing various personal care activities. This understanding is necessary if we are to structure educational programmes that will optimise motor skill acquisition and development.
