Intra-individual variability among children with ADHD on a working memory task: An EX-gaussian approach

Wendy M. Buzy, Deborah R. Medoff, Julie B Schweitzer

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


Intra-individual variability on a computer-based working memory task was examined among 25 children/adolescents with ADHD and 24 typically developing peers. Participants completed the Visual Serial Addition Task (VSAT) and reaction time data were fit to an ex-Gaussian distribution. ADHD participants demonstrated significantly more variable performance than controls, and effects of working memory load were observed. Event rate, however, had no influence on group differences in performance. Follow-up correlations revealed associations between VSAT performance and ADHD symptomatology. This study supports intra-individual variability as a hallmark feature of ADHD beyond the domain of response inhibition and reinforces the need to consider variability in ADHD more broadly.

Original languageEnglish (US)
Pages (from-to)441-459
Number of pages19
JournalChild Neuropsychology
Issue number5
StatePublished - Sep 2009


  • ADHD
  • Reaction time
  • Variability
  • Working memory

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Developmental and Educational Psychology
  • Neuropsychology and Physiological Psychology


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