Selective attention in attention deficit hyperactivity disorder subtypes

The moderating effect of perceptual load on visual selective attention was examined in three studies. In Study 1, children and young adults searched central displays of varying set size flanked by irrelevant peripheral distractors. Children's performance was as efficient as adults' under conditions of high but not low loads, suggesting that early selection engages early maturing neural systems, and late selection engages later maturing neural systems. In Study 2, four age groups were tested to better describe the development of selective attention, and placemarkers were set at the empty locations to examine perceptual grouping effects. Study 1's pattern replicated in all age groups, with onset of early selection occurring at lower loads for younger children.;Having established the perceptual load paradigm's properties and validity in children, Study 3 utilized this paradigm to examine early and late selective attention processes in children with the primarily inattentive (ADD-H) and combined subtypes (ADD+H) of Attention Deficit Hyperactivity Disorder (ADHD). Potential response modulation and arousal deficits were also examined. Results were mixed, but suggested the presence of an early selective attention deficit in children with ADD-H and ADD+H. Evidence for a interference control deficits, at least in boys with ADD+H, was also present. Results are discussed in relation to theories of cognitive and neural development, and the ramifications for neuropsychological theories of ADHD.