Divided attention in youth-onset psychosis and attention deficit/hyperactivity disorder.

The authors used pupillary dilations to test whether divided attention deficits in youth-onset psychosis and attention deficit/hyperactivity disorder (ADHD) were because of limitations in recruitment of cognitive resources or abnormalities in attention allocation. Eight- to 19-year-olds with youth-onset psychosis or ADHD were administered a divided attention test consisting of an auditory digit span (DS) task and a simple visual response time (RT) task. In 4 conditions, participants performed neither (no task), 1 (DS or RT only), or both tasks (dual). Dependent variables were DS accuracy, RT, and pupillary dilation to digits as an estimate of recruitment of cognitive resources. The authors found no evidence for an abnormal attention strategy in either disorder. Instead, results were consistent with the hypothesis that both clinical groups have limitations in resource recruitment. These limitations were more severe in psychosis than in ADHD. Findings indicate that both clinical groups had difficulties in regulating physiological arousal on a moment-to-moment basis in accordance with task demands. Findings also demonstrate the importance of taking into account difficulties that constrain performance on simple tasks before interpreting impairments on complex tasks.