title: Time perception deficits in attention-deficit/ hyperactivity disorder and comorbid reading difficulties in child and adolescent samples.
abstract: BACKGROUND
  Our objective was to investigate time perception in Attention-Deficit/Hyperactivity Disorder (ADHD) with and without comorbid reading difficulties (RD) in child and adolescent participants.
  
  
  METHODS
  In study 1, 50 children with ADHD (31 ADHD, 19 ADHD+RD) and age-matched healthy controls (n = 50) completed three psychophysical tasks: duration discrimination (target duration of 400 ms versus a foil duration), frequency discrimination (a control condition to evaluate general perceptual ability), and a duration estimation task using the method of reproduction for intervals of 400 ms, 2000 ms, and 6000 ms. Study 2 used the same tasks with an adolescent sample (35 ADHD, 24 ADHD+RD, 39 controls).
  
  
  RESULTS
  In both studies, children and adolescents with ADHD and ADHD+RD displayed some impairments in duration discrimination and the precision with which they reproduced the intervals on the estimation task, particularly the shorter 400 ms interval. The most severe impairments tended to occur in the comorbid ADHD+RD group. No impairments were found on the frequency discrimination task. ADHD participants also displayed significant intra-individual variability in their performance on the estimation task. Finally, short-term and working memory, estimated full-scale IQ, and teacher report of hyperactivity/impulsivity were found to differentially predict performance on the time perception measures in the adolescent clinical sample.
  
  
  CONCLUSIONS
  Deficits in duration discrimination, duration estimation, and intra-individual performance variability may have cascaded effects on the temporal organisation of behaviour in children and adolescents with ADHD and ADHD+RD.
authors.affiliation: Brain and Behaviour Research Programme, Research Institute of The Hospital for Sick Children, Toronto, Canada.
authors.forename: M E
authors.initials: ME
authors.lastname: Toplak
authors.forename: J J
authors.initials: JJ
authors.lastname: Rucklidge
authors.forename: R
authors.initials: R
authors.lastname: Hetherington
authors.forename: S C F
authors.initials: SC
authors.lastname: John
authors.forename: R
authors.initials: R
authors.lastname: Tannock
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology* / Q000523:psychology; D002648:Child; D015897:Comorbidity; D004410:Dyslexia / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D012737:Sex Factors; D013998:Time Perception