title: Motivational effects on motor timing in attention-deficit/hyperactivity disorder.
abstract: OBJECTIVE
  This study was designed to clarify whether poor performance of children with attention-deficit/hyperactivity disorder (ADHD) on motor timing tasks reflects a true deficit in the temporal organization of motor output or is due to a lack of intrinsic motivation.
  
  
  METHODS
  Eighteen children with ADHD (age 8-12) were compared with 18 age- and gender-matched normal controls with respect to timing precision, timing variability, and the frequency of extreme under- and overestimations during a 1-second interval production task. Monetary reward, response cost, and no reward were implemented to manipulate motivation.
  
  
  RESULTS
  Children with ADHD produced significantly more inaccurate and more variable time intervals and exhibited a larger number of extreme over- and underestimations than control children. Although all children performed significantly better when monetary incentives were applied, group differences were not eliminated.
  
  
  CONCLUSIONS
  In this study, no evidence was found for a motivational deficit as an explanation for impaired performance on a time production task in ADHD. Rather, results provide clear support for a generic motor timing deficit, probably due to a dysfunctional frontostriatocerebellar network involved in temporal aspects of motor preparation.
authors.affiliation: Department of Clinical Neuropsychology, Vrije Universiteit, 1081 BT Amsterdam, the Netherlands. cs.van.meel@psy.vu.nl
authors.forename: Catharina S
authors.initials: CS
authors.lastname: Van Meel
authors.forename: Jaap
authors.initials: J
authors.lastname: Oosterlaan
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Heslenfeld
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Sergeant
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000503:physiopathology*; D002531:Cerebellum / Q000503:physiopathology; D002648:Child; D002653:Child Behavior Disorders / Q000175:diagnosis / Q000453:epidemiology; D015897:Comorbidity; D003342:Corpus Striatum / Q000503:physiopathology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D008297:Male; D009042:Motivation; D009415:Nerve Net / Q000503:physiopathology; D011597:Psychomotor Performance / Q000502:physiology*; D012201:Reward; D013997:Time Factors