Jitter Reduces Response-Time Variability in ADHD: An Ex-Gaussian Analysis

Ryan W.Y. Lee, Lisa A. Jacobson, Alison E. Pritchard, Matthew S. Ryan, Qilu Yu, Martha B. Denckla, Stewart Mostofsky, E. Mark Mahone

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Objective: “Jitter” involves randomization of intervals between stimulus events. Compared with controls, individuals with ADHD demonstrate greater intrasubject variability (ISV) performing tasks with fixed interstimulus intervals (ISIs). Because Gaussian curves mask the effect of extremely slow or fast response times (RTs), ex-Gaussian approaches have been applied to study ISV. Method: This study applied ex-Gaussian analysis to examine the effects of jitter on RT variability in children with and without ADHD. A total of 75 children, aged 9 to 14 years (44 ADHD, 31 controls), completed a go/no-go test with two conditions: fixed ISI and jittered ISI. Results: ADHD children showed greater variability, driven by elevations in exponential (tau), but not normal (sigma) components of the RT distribution. Jitter decreased tau in ADHD to levels not statistically different than controls, reducing lapses in performance characteristic of impaired response control. Conclusion: Jitter may provide a nonpharmacologic mechanism to facilitate readiness to respond and reduce lapses from sustained (controlled) performance.

Original languageEnglish (US)
Pages (from-to)794-804
Number of pages11
JournalJournal of Attention Disorders
Issue number9
StatePublished - Sep 6 2015


  • ADHD
  • attention
  • ex-Gaussian
  • executive function
  • jitter
  • response time
  • statistics
  • variability

ASJC Scopus subject areas

  • Developmental and Educational Psychology
  • Clinical Psychology


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