Synchronization, anticipation, and consistency in motor timing of childrenwith dimensionally defined attention deficit hyperactivity behaviour

We tested the hypothesis that children with hyperactive behaviour are impai red in the temporal organization of their motor output. The performance of 11 boys, scoring above a cut-off on standard scales of overactivity and ina ttention, was compared to that of controls in progressively more complex Mo tor-timing tasks. The tasks administered required self-paced and externally paced Sensorimotor Synchronization and Sensorimotor Anticipation. Deficits ata perceptual level were investigated with a Time-discrimination task. As hypothesized, we found that hyperactive children had no deficits in their perception of time but were impaired in timing their motor output. Hyperact ive children were more inconsistent than controls in maintaining a freely c hosen tapping rhythm, in synchronizing and in anticipating their motor resp onse to external visual stimulation.