Timing of bimanual alternating finger-tapping sequences in adolescents with mental retardation: a pilot study.

We examined differences between the synchronization and self-pacing tasks using repetitive tapping with alternate hands. 9 adolescents with mental retardation made faster and more variable movements on the self-pacing task than on the synchronization task at target intervals of 400 and 800 msec. This suggests that they were able to coordinate the timing of individual responses with individual stimuli on the synchronization task but on the self-pacing task they controlled the timing by memory or generation or setting of an incorrect timer rate.