ABNORMAL PROCESSING OF IRRELEVANT INFORMATION IN ATTENTION-DEFICIT HYPERACTIVITY DISORDER

The presence of a selective attention deficit in children with attenti on deficit hyperactivity disorder (ADHD) was investigated by administe ring a trial-by-trial version of the Stroop Color-Naming Task to child ren, aged 9-12, with ADHD (n = 19) and age-matched normal control chil dren (n = 19). Performance was evaluated on both interference and faci litation components of the task. On the standard version of the task, with equal numbers of color words and neutral words, children with ADH D showed increased Stroop interference (prolongation of color-naming t imes by color-incongruent stimuli) but normal amounts of facilitation (speeding of color naming by color-congruent stimuli). This finding su ggests that children with ADHD show increased disruption of color-nami ng performance by task-irrelevant information, probably secondary to d ecreased attentional control over the interference process. In contras t to findings of studies in adults, both groups of children failed to use an attentional strategy to reduce interference when they were admi nistered blocks of trials that varied their expectancy for color word trials. This precluded a direct test of the diminished control hypothe sis. There were no significant correlations between abnormal Stroop pe rformance and impairment on the Continuous Performance Test or the Wis consin Card Sorting Test or measures of IQ or reading performance. The implications of these findings for our understanding of information-p rocessing deficits in children with ADHD and of the neurobiological un derpinnings of these deficits are discussed.