Children with a learning disorder show prospective control impairments during visuomanual tracking

To examine whether children with a learning disorder (LD) are able to use prospective motor control, 30 children with LD (mean age 8 years and 11 months) and an age- and gender-matched control group were asked to smoothly track an accelerating dot presented on a monitor by moving an electronic pen on a digitizer. Children with LD performed worse than controls: the number of drawn circles was smaller, the maximum target velocity lower, and the number of submovements was higher. It is suggested that a decreased ability to predict the movement of the target leads to impaired visuomanual tracking in children with LD. Furthermore, children with LD did not improve from the 1st to the 2nd trial, possibly as a result of slower visuomotor adaptation processes.