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J Atten Disord. 2015 Sep;19(9):794-804. doi: 10.1177/1087054712464269. Epub 2012 Nov 27.

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

Author information

1
Kennedy Krieger Institute, Baltimore, MD, USA.
2
Kennedy Krieger Institute, Baltimore, MD, USA Johns Hopkins University, Baltimore, MD, USA.
3
Johns Hopkins University, Baltimore, MD, USA.
4
Kennedy Krieger Institute, Baltimore, MD, USA Johns Hopkins University, Baltimore, MD, USA mahone@kennedykrieger.org.

Abstract

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.

KEYWORDS:

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

PMID:
23190614
PMCID:
PMC3600392
DOI:
10.1177/1087054712464269
[Indexed for MEDLINE]
Free PMC Article

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