Time estimation and performance on reproduction tasks in subtypes of children with attention deficit hyperactivity disorder.

This study compared Hispanic children (ages 7 to 11) with combined type (CT, n=33) and inattentive type (IT, n=21) attention deficit hyperactivity disorder (ADHD) and a control group (n=25) on time-estimation and time-reproduction tasks. The ADHD groups showed larger errors in time reproduction but not in time estimation than the control group, and the groups did not differ from each other on their performance on this task. Individual differences could not be accounted for by oppositional-defiance ratings and low math or reading scores. Although various measures of executive functioning did not make significant unique contributions to time estimation performance, those of interference control and nonverbal working memory did so to the time-reproduction task. Findings suggest that ADHD is associated with a specific impairment in the capacity to reproduce rather than estimate time durations and that this may be related to the children's deficits in inhibition and working memory.