title: Delta plots in the study of individual differences: new tools reveal response inhibition deficits in AD/Hd that are eliminated by methylphenidate treatment.
abstract: The authors highlight the utility of distribution-analytical techniques in the study of individual differences and clinical disorders. Cognitive deficits associated with attention-deficit/hyperactivity disorder (AD/HD) were examined by using delta-plot analyses of performance data (reaction time and accuracy) obtained through the use of a prototypical conflict task, the Eriksen flanker task. In 20 children with AD/HD (compared with matched control participants), overall performance measures indicated a marginal performance deficit. Delta-plot analyses indicated that performance deficits associated with AD/HD involve response inhibition but not automatic response activation. In a within-subjects titration study, the response inhibition deficit was eliminated by methylphenidate treatment, but these effects were highly dose specific. The beneficial effect of methylphenidate was clarified further after correcting for inter-individual variation in sensitivity to medicine dosage.
authors.affiliation: Department of Psychology, University of Amsterdam, Amsterdam, Netherlands. k.r.ridderinkhof@uva.nl
authors.forename: K Richard
authors.initials: KR
authors.lastname: Ridderinkhof
authors.forename: Anouk
authors.initials: A
authors.lastname: Scheres
authors.forename: Jaap
authors.initials: J
authors.lastname: Oosterlaan
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Sergeant
mesh_terms: D001288:Attention / Q000187:drug effects; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000494:pharmacology / Q000627:therapeutic use*; D002648:Child; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D006801:Humans; D007206:Individuality; D007266:Inhibition, Psychological; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology / Q000627:therapeutic use*; D015233:Models, Statistical; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects*; D013647:Task Performance and Analysis; D016896:Treatment Outcome
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate