Abnormalities of imaged motor sequences in children with developmental coordination disorder.

The chronometry of real and imagined movements was investigated in a group of children with developmental coordination disorder (DCD) and a group of matched controls. The visually-guided pointing task was used to investigate the speed for accuracy trade-offs that occur as target size is varied for both real and imagined performance. In the control group, the speed for accuracy trade-off for both real and imagined performance conformed to Fitts' law. In the DCD group only real movements conformed to Fitts' law. This pattern of performance suggests that children with DCD have an impairment in the ability to generate internal representations of volitional movements. This may reflect part of a general impairment in the processing of efference copy in DCD.