title: Abnormal spatial asymmetry of selective attention in ADHD.
abstract: BACKGROUND
  Evidence for a selective attention abnormality in children with attention deficit hyperactivity disorder (ADHD) has been hard to identify using conventional methods from cognitive science. This study tested whether the presence of selective attention abnormalities in ADHD may vary as a function of perceptual load and target lateralisation. Given evidence of right-hemisphere dysfunction in ADHD we predicted increased interference effects for right, but not left-sided target displays, particularly under low perceptual load.
  
  
  METHODS
  Fourteen children with ADHD-C and 14 typically developing children were tested on a modified flanker task under low and high perceptual load. We also sought evidence for our hypothesis in a re-analysis of an independent data set (42 ADHD; 34 typically developing) in which load effects on selective attention in ADHD were previously examined (Huang-Pollock, Nigg, & Carr, 2005).
  
  
  RESULTS
  As predicted, all children showed evidence of greater interference by flankers under low compared with high perceptual load conditions. Crucially, however, children with ADHD showed the greatest interference effect for right-sided target displays under low but not high perceptual load. In contrast, typically developing children showed the greatest interference for left-sided target displays. The magnitude of interference for right-sided targets was also positively correlated with ADHD symptom levels. Re-analysis of an independent data set (Huang-Pollock et al., 2005) further confirmed our findings.
  
  
  CONCLUSIONS
  This study demonstrates that interference effects in children with ADHD and typically developing children are spatially asymmetrical but opposite in direction. The pattern of right-sided interference effects in children with ADHD suggests disruption within right hemisphere attentional networks in ADHD.
authors.affiliation: The University of Queensland, School of Psychology and Queensland Brain Institute, Brisbane, Australia. echan@psy.uq.edu.au
authors.forename: Edgar
authors.initials: E
authors.lastname: Chan
authors.forename: Jason B
authors.initials: JB
authors.lastname: Mattingley
authors.forename: Cynthia
authors.initials: C
authors.lastname: Huang-Pollock
authors.forename: Therese
authors.initials: T
authors.lastname: English
authors.forename: Robert
authors.initials: R
authors.lastname: Hester
authors.forename: Alasdair
authors.initials: A
authors.lastname: Vance
authors.forename: Mark A
authors.initials: MA
authors.lastname: Bellgrove
mesh_terms: D000293:Adolescent; D001288:Attention; D001289:Attention Deficit Disorder with Hyperactivity / Q000523:psychology*; D002648:Child; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011930:Reaction Time; D013028:Space Perception