SPATIAL ORIENTING AND FOCUSED ATTENTION IN ATTENTION-DEFICIT HYPERACTIVITY DISORDER

Seventeen children with attention deficit disorder (ADHD) and 10 norma l controls performed two tasks while event-related potentials were rec orded. ADHD subjects took part in two more sessions under methylphenid ate (MP) or placebo. In the spatial orienting task, invalidly cued tar gets elicited a longer reaction time (RT) and a P-3 that was longer in latency and greater in amplitude than did validly cued targets. Perfo rmance was similar for both groups, but the early portion of P-3 (300- 400 ms) was lower in amplitude for invalidly cued targets in ADHD subj ects. MP increased accuracy without affecting RT and shortened P-3 pea k latency and increased the amplitude of its early portion. In the foc used attention task, accuracy was greater for controls and MP, but the re were no RT differences. Attended stimuli elicited greater amplitude P-1, N-1, and P-3 than did nonattended stimuli, but these measures we re unaffected by diagnosis or medication.