title: Variability in time reproduction: difference in ADHD combined and inattentive subtypes.
abstract: OBJECTIVE
  To examine the relationship between time reproduction, performance variability, and sustained attention deficits in children with attention-deficit/hyperactivity disorder (ADHD) combined (ADHD-C) and inattentive (ADHD-I) subtypes, relative to matched controls.
  
  
  METHODS
  Participants (age range 7.1-14.1 years) performed a time reproduction task. A subset of the ADHD group was also tested on the Sustained Attention to Response Test. Absolute discrepancy, accuracy coefficient, and intraindividual variability scores on the time reproduction task were compared across the three groups (ADHD-C: N = 20; ADHD-I: N = 19; controls: N = 44) and correlated with the Sustained Attention to Response Test.
  
  
  RESULTS
  First, significantly better performance was observed in matched controls than in children with ADHD on the time reproduction task. Second, there was a significant difference between the two ADHD subtypes in the variability of the size of errors made at high time intervals (36-60 seconds). Third, intraindividual performance variability in the direction (over- versus underestimations) of time reproductions correlated with sustained attention performance.
  
  
  CONCLUSIONS
  Children with ADHD varied more in the size and direction of their time reproduction errors than control children. Those with ADHD-C demonstrated more intraindividual variability than did those with ADHD-I in the size of their errors. The data provide support for a relationship between sustained attention and time reproduction. This relationship has previously been inferred from common right-lateralized neural circuitry that is thought to subserve these processes.
authors.affiliation: Department of Psychology, Trinity College Institute of Neuroscience, Trinity College, Dublin 2, Ireland. cemullin@tcd.ie
authors.forename: Celine
authors.initials: C
authors.lastname: Mullins
authors.forename: Mark A
authors.initials: MA
authors.lastname: Bellgrove
authors.forename: Michael
authors.initials: M
authors.lastname: Gill
authors.forename: Ian H
authors.initials: IH
authors.lastname: Robertson
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000145:classification* / Q000175:diagnosis*; D002648:Child; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires