Comparison of sustained and selective attention in children who have mental retardation with and without attention deficit hyperactivity disorder.

Attention deficits have been demonstrated in children with attention deficit hyperactivity disorder (ADHD) in the general population, but little is known about attention deficits in children with ADHD who also have mental retardation. In this investigation, children with ADHD and mental retardation were compared to those with mental retardation without ADHD on tasks assessing sustained and selective attention. Although children with ADHD and mental retardation made fewer correct target detections and more commissions on a vigilance task, no compelling evidence emerged for sustained attention deficits. However, evidence did emerge that was suggestive of selective attention deficits in these children. Results also suggest that girls with mental retardation may be at a higher risk for ADHD than are girls in the general population.

Consequences of a motor programming deficit for rehearsal and written sentence comprehension.

The role of central motor processes in rehearsal was investigated by studying a brain-damaged patient with a severe articulatory impairment. Evidence is presented that his articulatory impairment is due to a disruption of motor programming rather than to peripheral muscle weakness. Despite his motor programming deficit, the patient showed normal auditory span and evidence of rehearsal for auditorily presented sequences of words. For visual presentation, span was reduced and there was no evidence of rehearsal. Also, the patient showed excellent sentence comprehension for syntactically complex sentences for both auditory and visual presentation. The results imply that central motor processes are not critical for normal short-term memory, at least for auditory presentation, and that reading comprehension does not depend on inner rehearsal.