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Previous experiments involving discrete unimanual tasks have shown that individuals with Down syndrome (DS) have auditory/verbal-motor deficits. The present study investigated unimanual and bimanual continuous perceptual-motor actions in adults with DS. Ten adults with DS, 10 typical adults, and 10 children drew continuous circles at increasing periods bimanually and unimanually with each hand. Movement was paced by either a visual or an auditory metronome. The results revealed that for circle shape and coordination measures, children and adults were more accurate with the visual metronome, whereas adults with DS were more accurate with the auditory metronome. In the unimanual tasks, adults with DS displayed hand asymmetries on spatial measures. In the bimanual task, however, adults with DS adopted an in-phase coordination pattern and stability more similar to adults than children. These results suggest that bimanual coordination in adults with DS is functioning effectively despite hand asymmetries evident in unimanual performance.
S.D. Ringenbach is with the Motor Development Laboratory at Arizona State University, Tempe, AZ 85287-0404. J.C. Kao was with the Motor Development Laboratory at Arizona State University at the time the study was conducted and is now with the Department of Human Performance at San José State University, San José, CA 95192. R. Chua is with the School of Human Kinetics at the University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1. B.K.V. Maraj is with the Perceptual Motor Behaviour Laboratory at the University of Alberta, Edmonton, Alberta, Canada T6G 2H9. D.J. Weeks is with the School of Kinesiology at Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.