Separable/integral classification by hyperactive and normal children

Abstract

This research tested the hypothesis that information-processing deficits associated with hyperactivity implicate a self-regulatory dysfunction. Hyperactive and control children were compared on nonspeeded classification tasks. In Studies 1 and 2, children classified sets of either three (triads) or four (tetrads) stimuli. The stimuli varied simultaneously on size and brightness or on length and density. They could be classified analytically (separably) on the basis of identical values for one dimension and holistically (integrally) on the basis of overall similarity. Control children made an equal number of dimensional classifications for triads and for tetrads. As predicted, however, hyperactive children made fewer dimensional classifications for tetrads, suggesting that they apparently resorted to less effortful holistic responding under the increased processing load. In an unexpected finding in Study 1, older hyperactive children appeared to behave like younger controls, making more dimensional classifications when size, rather than brightness, was the shared dimension. Study 3 explored the possibility that hyperactive children lagged behind the controls in their responding to the shared dimensions. Three age groups of normal children (mean ages: 5, 8, and 11 years) and adults were asked to classify stimuli that varied on size and brightness. Consistent with the lag hypothesis, normal preschoolers behaved like the young hyperactive children in Study 1, classifying equally on the basis of size and brightness. The discussion focuses on the contribution of processing load and stimulus salience to the cognitive deficits of hyperactive children.

Cerebrospinal Fluid Homovanillic Acid Predicts Behavioral Response to Stimulants in 45 Boys with Attention Deficit/Hyperactivity Disorder

“…Neuropsychological evaluations have consistently found that ADHD children have a "neurodevelopmental lag" of approximately 2 to 4 years, particularly in putative tests of frontal function (Kinsbourne 1973;Chelune et al 1986;Amin et al 1993). Although CSF monoamines from truly normal children have never been examined, studies in various pediatric contrast groups demonstrate that CSF HVA decreases substantially across the pediatric age range (Leckman et al 1980;Hedner et al 1986;Kruesi et al 1988b).…”

Effects of methylphenidate on complex cognitive processing in attention-deficit hyperactivity disorder.

“…They are less likely to use the more active, effortful strategy of grouping words when learning word lists (August, 1987; O’Neill & Douglas, 1996). They also tend to use less effortful strategies to categorize items in stimulus-classification tasks (Amin, Douglas, Mendelson, & Dufresne, 1993). These findings suggest that our ADHD group would have relatively more difficulty than controls would on the high-load conditions of the VMS, because to deal with the higher loads it is necessary to make an organized, effortful search through the large number of items in the search and memory sets and to coordinate the two searches.…”

Working Memory Deficits in ADHD

“…The role of developmental differences in ADHD has previously been highlighted by studies which have employed more complex measures of executive functioning (Amin, Douglas, Mendelson, & Dufresne, 1993;Chelune, Ferguson, Koon, & Dickey, 1986). Using the Wisconsin Card Sorting Test (WCST) and similar classification tasks, both Chelune et al (1986) and Amin et al (1993) found that the performance of older children with ADHD was compared to control children of 2 to 3 years of their junior (i.e., 10-to 12-year-old children with ADHD performed like 8-to 9-yearold controls). Being cross-sectional in nature, these studies suggest that, at least on these tasks, the responding of children with ADHD followed a similar, but delayed developmental trajectory to that of controls.…”