Cited by 104Attention Deficit Hyperactivity DisorderNeural and Behavioral Psychology StudiesDevelopmental and Educational Neuropsychology

The DOI matches its Crossref record; 83 of the 83 references it cites were found in a registry or an index; none of the 88 sources its claims cite is checked for support yet.

Decomposing attention-deficit/hyperactivity disorder (ADHD)-related effects in response speed and variability.

Open access
Karalunas, Sarah L., Huang-Pollock, Cynthia L., Nigg, Joel T.·2012·Neuropsychology

Abstract

OBJECTIVE: Slow and variable reaction times (RTs) on fast tasks are such a prominent feature of attention-deficit/hyperactivity disorder (ADHD) that any theory must account for them. However, this has proven difficult because the cognitive mechanisms responsible for this effect remain unexplained. Although speed and variability are typically correlated, it is unclear whether single or multiple mechanisms are responsible for group differences in each. RTs are a result of several semi-independent processes, including stimulus encoding, rate of information processing, speed-accuracy trade-offs, and motor response, which have not been previously well characterized. METHOD: A diffusion model was applied to RTs from a forced-choice RT paradigm in two large, independent case-control samples (NCohort 1 = 214 and NCohort 2 = 172). The decomposition measured three validated parameters that account for the full RT distribution and assessed reproducibility of ADHD effects. RESULTS: In both samples, group differences in traditional RT variables were explained by slow information processing speed, and unrelated to speed-accuracy trade-offs or nondecisional processes (e.g., encoding, motor response). CONCLUSIONS: RT speed and variability in ADHD may be explained by a single information processing parameter, potentially simplifying explanations that assume different mechanisms are required to account for group differences in the mean and variability of RTs.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

Diffusion modeling in two independent case-control samples found that ADHD-related slower and more variable responses were explained by slower information accumulation (drift rate), not by speed-accuracy trade-off or non-decision processes. The authors suggest a single processing parameter may account for both mean and variability effects in ADHD.

Key findings

  • In Cohort 1 (214 children: 164 ADHD, 50 controls), the ADHD group had lower go-trial accuracy (d = 0.28) and greater RT variability (d = 0.48), with no mean RT difference; diffusion analysis showed slower drift rate (d = 0.34) but no group differences in boundary separation or non-decision time.
  • In Cohort 2 (172 children: 81 ADHD, 91 controls), the ADHD group again had lower accuracy (d = 0.65) and greater RT variability (d = 0.78), with no mean RT difference; drift rate was slower (d = 0.68), while boundary separation and non-decision time did not differ.
  • Group effects on accuracy, RT variability, and drift rate did not significantly differ by cohort, though Cohort 1 had lower accuracy, less RT variability, faster drift, older age, lower estimated IQ, and more families below the federal poverty limit than Cohort 2.
  • The authors conclude that slow drift rate may be a single mechanism underlying ADHD-related response speed and variability, potentially linked to neural signal-to-noise ratio.

Methods

  • Two independent case-control cohorts were recruited in different cities/states using identical screening and diagnostic procedures; diagnoses used parent/teacher rating scales, a semi-structured clinical interview, IQ testing, and clinical team consensus.
  • Participants completed a tracking stop task; analyses used go trials (75% of trials) requiring an X/O choice response, with 32 practice trials and 4 blocks of 64 experimental trials. Diffusion parameters—drift rate, boundary separation, and non-decision time—were estimated from full correct and error RT distributions using Fast-dm; anticipation RTs under 150 ms were removed.
  • MANCOVAs compared ADHD and control groups on mean RT, RT SD, accuracy, and the three diffusion parameters, with age and estimated IQ as covariates; gender, ODD symptoms, and medication status were initially considered but dropped as non-significant.

Limitations

  • The paper states that cohort differences in task performance and drift rate were not explained by age, IQ, or income and likely reflect unmeasured sampling or procedural variation; additional samples are needed to estimate the population effect.
  • The paper notes that the diffusion model may not capture attention lapses or contaminant RTs, that stop-task demands may affect speed-accuracy and motor preparation strategies, and that the model addresses single-step decisions rather than multi-step problem solving.
  • Evident from the text: the cohorts differed in age range (7–18 vs. 7–12) and sample composition, and ADHD subtypes were collapsed after showing no outcome differences, which may limit generalization across developmental stages and subtype-specific effects.

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Integrity signals

Registry

Crossref · 10.1037/a0029936

Cites

83 of 83 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 88 cited sources checked · 0 supported · 0 flagged

Show all 73 claims

  • It may state two separate claims as one. 28
  • The quote only partly states this claim. 9
  • Probably not a substantial claim. 26
53 of 53
  • The paper relies on this without support.

    Mean and variability of reaction time are highly correlated.

    “although mean and variability of RT are highly correlated”
  • The authors state this as an assumption.

    In a diffusion model, information about a stimulus is accumulated via a noisy process until a decision criterion is met, at which point a response is initiated.

    “a diffusion model assumes that information about a stimulus is accumulated via a noisy information accumulation process until a decision criterion is met, at which point a response is initiated”
  • The authors state this as an assumption.

    Participants in forced-choice tasks set criteria for how much information they require before committing to a response.

    “participants are assumed to set criteria for how much information they require to commit to either of the response options”
  • The authors state this as an assumption.

    Individuals who require less information respond more quickly but make more errors than those who require more information.

    “Individuals who require less information will respond more quickly but will also make more errors than those who require more information.”
  • The authors state this as an assumption.

    Processes not directly related to the response decision, such as stimulus encoding and motor preparation, influence final reaction time and must be modeled.

    “processes that are not directly related to the response decision, such as stimulus encoding and motor preparation, also influence the final RT and so must be modeled”
  • The paper relies on this without support.

    Traditional RT variables show broad patterns of association with structural and functional neuroimaging measures.

    “Whereas traditional RT variables show broad patterns of association with structural and functional neuroimaging measures”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Cohort 2 diffusion MANCOVA repeats the degrees-of-freedom mismatch

    Minor

    The two Cohort 2 MANCOVAs likewise have three outcomes and the same covariates, yet the diffusion test reports F[5,164] rather than degrees of freedom consistent with the traditional-measures test's F[3,166].

1 of 1

Citations

Cites

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Show all 83 references

Research works printed but not linked: 2

  1. Huang-Pollock CL Karalunas SL Tam H Moore AN in press Evaluating vigilance deficits in adhd: A meta-analysis of cpt performance Journal of Abnormal Psychology PMC3664643 22428793
  2. Karalunas SL Huang-Pollock CL (revise and resubmit) Integrating evidence of slow rts and impaired executive functions using a diffusion model framework Journal of Abnormal Child Psychology PMC3679296 23334775

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Items 101–104 of 104

Metadata

Authors
Karalunas, S. L., Huang-Pollock, C. L., & Nigg, J. T.
Affiliations
Oregon Health & Science University (US)
Venue
Neuropsychology
Published
2012
Volume
26
Issue
6
Pages
684-694
ISSN
  • 0894-4105 (ISSN-L)
  • 1931-1559
OpenAlex
W1967147115
Cited by
104
References
83
Citations by year
2026: 5 · 2025: 10 · 2024: 5 · 2023: 7 · 2022: 7 · 2021: 11 · 2020: 8 · 2019: 9 · 2018: 9 · 2017: 2 · 2016: 14 · 2015: 4 · 2014: 7 · 2013: 6
FWCI
3.86
Type
journal article
Language
en
Open access
Locations
  • Neuropsychology (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
National Institute of Mental Health (F32MH098632, R01MH059105, R01MH084947)
Topics
  • Health Sciences › Medicine › Psychiatry and Mental health › Attention Deficit Hyperactivity Disorder
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Neural and Behavioral Psychology Studies
  • Social Sciences › Psychology › Neuropsychology and Physiological Psychology › Developmental and Educational Neuropsychology
Keywords
attention deficit hyperactivity disorder, reaction time, response variability, diffusion models, processing speed, speed-accuracy trade-off, stimulus encoding, motor response
MeSH terms
Adolescent, Attention Deficit Disorder with Hyperactivity, Child, Female, Humans, Inhibition, Psychological, Male, Models, Psychological, Neuropsychological Tests, Psychiatric Status Rating Scales, Psychomotor Performance, Reaction Time, Cohort Studies, Case-Control Studies

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