title: Behavioural and neurophysiological correlates of dyslexia in the continuous performance task.
abstract: OBJECTIVE
  To investigate whether attentional difficulties are a "core" feature of developmental Dyslexia.
  
  
  METHODS
  Behavioural indices and event related potentials (ERPs) were recorded from 10 dyslexic participants (ages 15.5-17.4) and 10 control participants (ages 14.4-18.3) in the Continuous Performance Task (CPT), an established test of attentional performance. Participants were screened to ensure that none was diagnosable as attention deficit (ADHD).
  
  
  RESULTS
  There were no significant differences in mean reaction time, error rate or sustained attention between the groups. By contrast, the P3 amplitude was significantly smaller and its latency significantly longer for the dyslexic group. This component was significantly lateralised in controls, whereas in dyslexics it was symmetrical.
  
  
  CONCLUSIONS
  Under the relatively light workload conditions of the CPT, "pure" dyslexic participants showed no behavioural signs of attentional difficulties. The attenuated, delayed and symmetrical ERPs in our dyslexic group may reflect abnormal information processing in the right parietal lobe and abnormal interhemispheric asymmetry in Dyslexia.
  
  
  CONCLUSIONS
  The behavioural data suggest that abnormal attentional performance is not a "core" feature of developmental Dyslexia, and highlight the importance of distinguishing between dyslexic participants with and without ADHD symptoms. The presence of electrophysiological markers of Dyslexia in CPT revealed the atypical brain organisation that characterises "pure" Dyslexia.
authors.affiliation: Department of Psychology, University of Sheffield, Sheffield S10 2TP, UK. N.A.Taroyan@sheffield.ac.uk
authors.forename: N A
authors.initials: NA
authors.lastname: Taroyan
authors.forename: R I
authors.initials: RI
authors.lastname: Nicolson
authors.forename: A J
authors.initials: AJ
authors.lastname: Fawcett
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001288:Attention; D001519:Behavior / Q000502:physiology*; D004410:Dyslexia / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time