Down syndrome and extended practice of a complex motor task.

Mentally retarded subjects with and without Down syndrome made 2,400 responses on a discrete pursuit-tracking task. Both groups showed significant improvement on the task such that their performance was comparable to nonretarded subjects at the same functional level. Although the previously noted failure (Blais & Kerr, 1986; Kerr & Blais, 1985) of the subjects with Down syndrome to spontaneously use the directional probability information available in the task was moderated, differences remained that may reflect processing limitations.