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Cited by 324Attention Deficit Hyperactivity DisorderNeural and Behavioral Psychology StudiesDevelopmental and Educational Neuropsychology

Reaction Time Variability in ADHD: A Review

Open access
Tamm, Leanne, Narad, Megan E., Antonini, Tanya N., O'Brien, Kathleen M., Hawk, Larry W., Epstein, Jeffery N.·2012·Neurotherapeutics
DOI 10.1007/s13311-012-0138-5PMC PMC3441931
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Abstract

For the past decade, intra-individual variability in reaction times on computerized tasks has become a central focus of cognitive research on Attention-Deficit/Hyperactivity Disorder (ADHD). Numerous studies document increased reaction time variability among children and adults with ADHD, relative to typically developing controls. However, direct comparisons with other disorders with heightened reaction time variability are virtually nonexistent, despite their potential to inform our understanding of the phenomenon. A growing literature examines the sensitivity of reaction time variability to theoretically and clinically relevant manipulations. There is strong evidence that stimulus treatment reduces reaction time variability during a range of cognitive tasks, but the literature is mixed regarding the impact of motivational incentives and variation in stimulus event rate. Most studies of reaction time variability implicitly assume that heightened reaction time variability reflects occasional lapses in attention, and the dominant neurophysiological interpretation suggests this variability is linked to intrusions of task-negative brain network activity during task performance. Work examining the behavioral and neurophysiological correlates of reaction time variability provides some support for these hypotheses, but considerably more work is needed in this area. Finally, because conclusions from each of domains reviewed are limited by the wide range of measures used to measure reaction time variability, this review highlights the need for increased attention to the cognitive and motivational context in which variability is assessed and recommends that future work always supplement macro-level variability indices with metrics that isolate particular components of reaction time variability.

Verified 2026-10-06 · 18 references not checked yet

AI snapshot

Written from the paper’s full text.

TL;DR

This review synthesizes evidence that ADHD is associated with greater intra-individual reaction time variability across computerized tasks, with intermittent long responses as a key component. It argues that this variability is not specific to ADHD and that measurement choices, task context, and neurophysiological models need refinement.

Key findings

  • ADHD groups show higher reaction time variability than controls across working memory, attention, inhibitory control, and choice-discrimination tasks, in both children and adults; these differences are often larger than those seen on other neuropsychological indicators.
  • Elevated variability also occurs in autism, schizophrenia, bipolar disorder with psychotic symptoms, traumatic brain injury, early Alzheimer’s dementia, and aging/dementia, so it is not unique to ADHD.
  • Ex-Gaussian studies suggest ADHD-related variability is driven mainly by tau, the right-skewed tail of the reaction time distribution, consistent with occasional attentional lapses; standard deviation measures correlate strongly with mean reaction time (about 0.90), complicating interpretation, and one study reported a small fast-portion effect size of 0.08.
  • Stimulant medication attenuates or normalizes variability, especially tau and Fourier-based oscillation measures; faster stimulus event rates reduce ADHD-related variability, while reward/incentive effects are mixed, with some evidence that fast event rate plus reward may work synergistically. Neurophysiological accounts implicate frontal dysfunction, poor default-mode network suppression, and lower signal-to-noise ratios.

Methods

  • Narrative review of published cognitive, behavioral, neuroimaging, task-manipulation, and medication studies on reaction time variability in ADHD; no new participants or primary data are reported.
  • The main analysis is a qualitative synthesis across studies, with emphasis on ex-Gaussian and Fourier-transform metrics where available.

Limitations

  • Stated: conclusions are constrained by the wide range of variability measures used; most studies rely on reaction time standard deviation or coefficient of variation, which are too molar and confounded with mean reaction time, so component-specific metrics are needed.
  • Stated: few direct comparisons exist with other disorders showing high variability, few neuroimaging studies specifically examine variability in ADHD, findings for incentives and event rate are mixed, and it remains unclear whether variability is a cause or consequence.
  • Evident from the text: as a narrative review, it does not report a systematic search strategy, risk-of-bias assessment, or meta-analytic pooling.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1007/s13311-012-0138-5

Cites

96 of 114 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 97 cited sources checked · 0 supported · 0 flagged

  • Premisecitation

    Research using ex-Gaussian parameters has shown that ADHD-related reaction time variability is largely due to an elevation in tau.

    “Research using ex-Gaussian parameters has shown that ADHD-related RTV is largely the result of an elevation in tau [10,13,32].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [10] Hervey, 2006, Eugene Arnold L, Keith Conners C, et al. Reaction time distribution analysis of neuropsychological performance in an ADHD sample, Child Neuropsychol source

      Not checked in the free run.

    • cites [13] Vaurio, 2009, Increased intra-individual reaction time variability in attention-deficit/hyperactivity disorder across response inhibition tasks with different cognitive demands, Neuropsychologia source

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    • cites [32] Leth-Steensen, 2000, Mean response times, variability, and skew in the responding of ADHD children: a response time distributional approach, Acta Psychol (Amst) source

      Not checked in the free run.

  • Premisecitation

    Children and adults with ADHD show greater intra-individual reaction time variability on computerized tasks than typically developing controls.

    “Numerous studies document increased reaction time variability among children and adults with ADHD, relative to typically developing controls.”
    • Also stated in: § Introduction · boosted
      “Elevated RTV among individuals with ADHD compared with typically-developing children has been documented across multiple studies using a wide variety of computerized tasks”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [5] Sonuga-Barke, 2008, Executive dysfunction and delay aversion in attention deficit hyperactivity disorder: nosologic and diagnostic implications, Child Adolesc Psychiatr Clin N Am source

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  • Premisecitation

    There are few, if any, differences in reaction time variability across ADHD subtypes.

    “Regarding the differences between ADHD subtypes on RTV in the research conducted to date, there are few, if any, differences in RTV across the ADHD subtypes [13,[47][48][49][50][51].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13,[47][48][49][50][51]

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  • Interpretationreasoning

    Both reaction time standard deviation and coefficient of variation are too molar to provide information about specific aspects of reaction time variability, particularly the positive skew expected from occasional attentional lapses.

    “However, both RTSD and CV face a second obstacle.They are too molar to provide information regarding specific aspects of the RTV construct, particularly the asymmetrical positive skew that occasional lapses in attention, which would be expected to produce.”
    Quote in the paperSubstantial claim
  • Premisecitation

    ADHD between-group differences in reaction time variability tend to be larger than most other neuropsychological indicators.

    “These ADHD between-group differences on RTV tend to be larger in magnitude than most other neuropsychological indicators [15].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [15] Epstein, 2011, Evidence for higher reaction time variability for children with ADHD on a range of cognitive tasks including reward and event rate manipulations, Neuropsychology source

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  • Classified as probably not a substantial claim. 7

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    Premisecitation

    Reaction time variability correlates with measures of behavioral inattention, and in a minority of studies also with hyperactivity-impulsivity.

    “Where relations between RTV and the ADHD symptom domains have been examined, RTV has correlated with measures of behavioral inattention [48,52,53] but has also been found to correlate with hyperactivityimpulsivity in a minority of studies”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [48] Nigg, 1999, The ADHD response-inhibition deficit as measured by the stop task: replication with DSM-IV combined type, extension, and qualification, J Abnorm Child Psychol source

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    • cites [52] Wahlstedt, 2009, Neuropsychological deficits in relation to symptoms of ADHD: independent contributions and interactions, Child Neuropsychol source

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    • cites [53] Wahlstedt, 2009, Heterogeneity in ADHD: neuropsychological pathways, comorbidity and symptom domains, J Abnorm Child Psychol source

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    • cites [54] Gomez-Guerrero, 2011, Response-time variability is related to parent ratings of inattention, hyperactivity, and executive function, J Atten Disord source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Several non-mutually exclusive hypotheses about reaction time variability in ADHD have been proposed, including temporal processing deficit, low-frequency neuronal modulation deficit, executive attention deployment inefficiency, sustained attention deficit, and energetic state regulation difficulties.

    “Hypotheses emphasizing several factors have been proposed: a temporal processing deficit [34], a deficit in the ability to appropriately modulate very low-frequency fluctuations in neuronal activity [35], inefficiency in the deployment of attention by executive control processes [36], deficit of sustained attention [10,32], and difficulties with the regulation of energetic state [14,[37][38][39].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [34] Toplak, 2006, Temporal information processing in ADHD: findings to date and new methods, J Neurosci Methods source

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    • cites [35] Castellanos, 2005, Varieties of attention-deficit/hyperactivity disorder-related intra-individual variability, Biol Psychiatry source

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    • cites [36] Bellgrove, 2004, The functional neuroanatomical correlates of response variability: evidence from a response inhibition task, Neuropsychologia source

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    Premisecitation

    Populations with increased reaction time variability commonly have attentional problems, although the types of attentional difficulty vary considerably.

    “One commonality among these various populations with increased RTV are problems with attention, although there seems to be considerable variability in the types of attentional difficulties across populations”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [29] Egeland, 2010, Frequency of attention deficit in first-episode schizophrenia compared to ADHD, Appl Neuropsychol source

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    • cites [30] Thaler, 2010, Attention processing abnormalities in children with traumatic brain injury and attention-deficit/hyperactivity disorder: differential impairment of component processes, J Clin Exp Neuropsychol source

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    • cites [31] Parasuraman, 1993, Attention and driving. Assessment in elderly individuals with dementia, Clin Geriatr Med source

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    The precise psychological and neurophysiological meaning of reaction time variability in ADHD is debated.

    “However, the precise psychological and neurophysiological meaning of RTV in ADHD is continually being debated.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Reaction time standard deviation almost always correlates highly with mean reaction time, making speed and variability difficult to distinguish.

    “Unfortunately, RTSD almost always correlates quite highly (e.g., r00.90; [17]) with the mean reaction time [18,40,41] that 1 cannot distinguish speed and variability limiting the clarity of the psychological or neurophysiological interpretation.”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [17] Desman, 2008, Deficit in response inhibition in children with attention deficit/hyperactivity disorder (ADHD): impact of motivation?, Child Neuropsychol source

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    • cites [18] Adams, 2011, Does response variability predict distractibility among adults with attention-deficit/hyperactivity disorder?, Psychol Assess source

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    • cites [40] Wagenmakers, 2007, On the linear relation between the mean and the standard deviation of a response time distribution, Psychol Rev source

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    • cites [41] Epstein, 2011, Effects of stimulant medication, incentives, and event rate on reaction time variability in children with ADHD, Neuropsychopharmacology source

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    Premisecitation

    Very few studies have examined the periodicity of long reaction times, and their results are mixed regarding the frequency at which long reaction times occur.

    “Unfortunately, there have been very few studies that have examined the periodicity of long RTs, and results from these studies have been mixed in regard to the frequency at which long RTs occur [9,13,35,46].”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [9] Johnson, 2007, Response variability in attention deficit hyperactivity disorder: evidence for neuropsychological heterogeneity, Neuropsychologia source

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    • cites [13] Vaurio, 2009, Increased intra-individual reaction time variability in attention-deficit/hyperactivity disorder across response inhibition tasks with different cognitive demands, Neuropsychologia source

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    • cites [35] Castellanos, 2005, Varieties of attention-deficit/hyperactivity disorder-related intra-individual variability, Biol Psychiatry source

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    • cites [46] Di Martino, 2008, Decomposing intra-subject variability in children with attention-deficit/hyperactivity disorder, Biol Psychiatry source

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  • May combine two claims.

    Premisecitation

    One study using ex-Gaussian parameters reported significant but small differences between ADHD and control groups in the fast portion of the reaction time distribution, interpreted as different causal mechanisms for a potentially multidimensional reaction time variability construct.

    “It should also be noted that 1 study, using ex-Gaussian parameters, reported significant differences, albeit with a small effect size (0.08) between ADHD and control groups in the fast portion of the RT distribution, which was interpreted as reflecting different causal mechanisms for the potentially multidimensional construct of RTV [44].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [44] Williams, 2007, Reaction time performance in adolescents with attention deficit/hyperactivity disorder: evidence of inconsistency in the fast and slow portions of the RT distribution, J Clin Exp Neuropsychol source

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In ADHD research, reaction time variability is typically interpreted as reflecting occasional lapses in attention.

    “In ADHD research, RTV in ADHD is typically interpreted (at least implicitly) as reflecting occasional lapses in attention”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [10] Hervey, 2006, Eugene Arnold L, Keith Conners C, et al. Reaction time distribution analysis of neuropsychological performance in an ADHD sample, Child Neuropsychol source

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    • cites [32] Leth-Steensen, 2000, Mean response times, variability, and skew in the responding of ADHD children: a response time distributional approach, Acta Psychol (Amst) source

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    • cites [33] Epstein, 2010, Examining predictors of reaction times in children with ADHD and normal controls, J Int Neuropsychol Soc source

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  • May combine two claims.

    Interpretationreasoning

    Higher tau values reflect reaction time distributions with a larger rightward skew or tail, which is consistent with a lapse of attention framework.

    “Higher tau values are produced by RT distributions with a larger rightward skew or tail, consistent with a lapse of attention framework.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Elevated reaction time variability is not unique to ADHD; it has been observed in high functioning autism, schizophrenia, bipolar disorder with psychotic symptoms, traumatic brain injury, and early stage Alzheimer's dementia.

    “Elevated RTV has been observed in individuals with high functioning autism [20], schizophrenia [21], bipolar disorder with psychotic symptoms [22], traumatic brain injury [23][24][25][26], and early stage Alzheimer's dementia [27,28].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [20] Verte, 2005, Executive functioning in children with autism and Tourette syndrome, Dev Psychopathol source

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    • cites [21] Kaiser, 2008, Intra-individual reaction time variability in schizophrenia, depression and borderline personality disorder, Brain Cogn source

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    • cites [22] Bora, 2006, Sustained attention deficits in manic and euthymic patients with bipolar disorder, Prog Neuropsychopharmacol Biol Psychiatry source

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  • May combine two claims.

    Interpretationreasoning

    Omission errors are linked to attentional lapses, suggesting that long reaction times, the primary cause of reaction time variability, are due to inattention.

    “Omission errors occur when a patient does not respond to a target stimulus and has been linked to attentional lapses [56], thus suggesting that long RTs, the primary cause of RTV, are due to inattention.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [56] Corkum, 1993, Is the Continuous Performance Task a valuable research tool for use with children with Attention-Deficit-Hyperactivity Disorder?, J Child Psychol Psychiatry source

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  • May combine two claims.

    Interpretationreasoning

    The task-negative network among individuals with ADHD is of higher intensity and likely dysfunctional in connectivity.

    “The task-negative network among individuals with ADHD is of higher intensity and likely dysfunctional in terms of connectivity.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Some studies found that ADHD-related increases in reaction time variability are attenuated when rewards for performance are provided, whereas others have not found this effect of reward.

    “Some studies have found that ADHD-related increases in RTV are attenuated when rewards for performance are provided [12,14,[90][91][92], whereas others have not found this effect of reward [49,93].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [12,14,[90][91][92]

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    • cites [49] Shanahan, 2008, Do motivational incentives reduce the inhibition deficit in ADHD?, Dev Neuropsychol source

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    • cites [93] Luman, 2008, Modulation of response timein in ADHD, effects of reinforcement valence and magnitude, J Abnorm Child Psychol source

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  • May combine two claims.

    Premisecitation

    In a study examining individual ADHD symptoms, reaction time variability was significantly related to all 18 ADHD symptoms, suggesting no specificity between reaction time variability and specific ADHD behaviors.

    “In a study examining whether RTV was specifically correlated with individual ADHD symptoms (e.g., short attention span), significant relations were observed between RTV and all 18 ADHD symptoms, suggesting no specificity between RTVand specific ADHD behaviors [55].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [55] Epstein, 2003, Relations between Continuous Performance Test performance measures and ADHD behaviors, J Abnorm Child Psychol source

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  • May combine two claims.

    Interpretationcitation

    Individuals with lower reaction time variability tend to show increased activation in motor areas, suggesting that reliance on more efficient networks reduces reaction time variability.

    “It is interesting that individuals with lower RTV tend to display increased activation in motor areas [62], suggesting that reliance on more efficient networks, such as premotor circuitry rather than higher order cognitive networks, reduces RTV.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [62] Simmonds, 2007, Functional brain correlates of response time variability in children, Neuropsychologia source

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  • May combine two claims.

    Interpretationreasoning

    Neuroimaging research has linked reaction time variability to abnormalities in frontal lobe volumes and activation, as well as to insufficient suppression of the default mode network.

    “To date, neuroimaging research has linked RTV to both abnormalities in frontal lobe volumes and brain activation, as well as what appears to be insufficient suppression of the DMN.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Children with ADHD show pronounced slowing on the trial before an omission error and less pronounced slowing on trials following an omission error.

    “Children with ADHD demonstrated pronounced slowing (i.e., long RTs) on the trial before an omission error, as well as slowing, although not nearly as pronounced, on trials following an omission error.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [33] Epstein, 2010, Examining predictors of reaction times in children with ADHD and normal controls, J Int Neuropsychol Soc source

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    Premisecitation

    Individuals with ADHD display significantly higher resting-state activation and reduced default mode network homogeneity.

    “In general, individuals with ADHD display significantly higher resting state activation [70,71] and reduced DMN homogeneity [72][73][74][75][76].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [70] Tian, 2008, Enhanced resting-state brain activities in ADHD patients: a fMRI study, Brain Dev source

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    • cites [71] Tian, 2006, Altered resting-state functional connectivity patterns of anterior cingulate cortex in adolescents with attention deficit hyperactivity disorder, Neurosci Lett source

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    • cites [72][73][74][75][76]

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    Premisecitation

    Children with ADHD are less able to deactivate the default mode network than controls, and this inability is directly related to reaction time variability.

    “Children with ADHD have also been shown to be less able to deactivate the DMN than controls, and this inability to deactivate the DMN has been directly related to RTV [77].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [77] Fassbender, 2009, A lack of default network suppression is linked to increased distractibility in ADHD, Brain Res source

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  • May combine two claims.

    Interpretationreasoning

    Individuals with ADHD may possess dual deficits: more active task-negative activation at rest and less task-positive activation during cognitive performance.

    “One explanation for this set of results is that individuals with ADHD possess dual deficits such that not only do individuals with ADHD have more active tasknegative activation at rest, but they also have less task-positive activation during cognitive performance.”
    Quote in the paperSubstantial claim

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    Premisecitation

    Brain activation in the default mode network is negatively correlated with activation in task positive regions and positively correlated with reaction time fluctuations.

    “Brain activation in the DMN is negatively correlated with activation in task positive regions [65][66][67] and positively correlated with RT fluctuations [68].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [65][66][67]

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    • cites [68] Helps, 2009, The attenuation of very low frequency brain oscillations in transitions from a rest state to active attention, J Psychophysiol source

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    Interpretationreasoning

    Quickening the pace of the task creates a raised energetic state among children with ADHD, thereby normalizing reaction time variability.

    “Hence, quickening the pace of the task creates a raised energetic state among children with ADHD, thereby normalizing RTV.”
    Quote in the paperSubstantial claim

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    Interpretationcitation

    Signal-to-noise ratios are affected by an inability to consistently suppress the default mode network, which interferes with task positive activation if it remains active during cognitive performance.

    “Signal-to-noise ratios are affected by an inability to consistently suppress the DMN, which interferes with task positive activation if it remains activated during cognitive performance, [69].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [69] MacDonald, 2009, Neural underpinnings of within-person variability in cognitive functioning, Psychol Aging source

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    Interpretationreasoning

    As a result of these dual deficits, task-negative activation overcomes task-positive activation more frequently, leading to intermittent long reaction times and higher reaction time variability.

    “As a result, tasknegative activation overcomes task-positive activation more frequently, which leads to intermittent long RTs and thus higher levels of RTV.”
    Quote in the paperSubstantial claim

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    Interpretationreasoning

    Correlational neuroimaging studies suggest an overall pattern of higher frontal lobe activation, particularly in the rostral supplementary motor area, but do not specifically link long reaction times to increased frontal activity.

    “Such correlational studies suggest an overall pattern of higher frontal lobe activation, particularly the rostral supplementary motor area, but do not specifically link instances of long RTs to increased frontal lobe activity.”
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  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    The state regulation dysfunction model suggests that short event rates may increase activation states, whereas long event rates may lead to underactivation.

    “One explanation for this pattern of effects is provided by the state regulation dysfunction model, which suggests that short ERs may increase activation states, whereas long ERs may lead to underactivation”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [86] van der Meere, 2005, Response inhibition and Attention Deficit Hyperactivity Disorder with and without Oppositional Defiant Disorder screened from a community sample, Dev Neuropsychol source

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    • cites [83] Sergeant, 2005, Modeling attention-deficit/hyperactivity disorder: a critical appraisal of the cognitive-energetic model, Biol Psychiatry source

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    Interpretationcitation

    Research on reaction time variability and ADHD symptom domains or subtypes has not convincingly associated reaction time variability with either symptom domain or any specific symptom, although relations with inattention are more consistent.

    “Research examining relations between RTV and the ADHD symptom domains or ADHD subtypes has not been convincingly associated with either ADHD symptom domain or any specific ADHD symptoms, although relations between RTV and inattention seem to be more consistent in the literature [48,52,53].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [48] Nigg, 1999, The ADHD response-inhibition deficit as measured by the stop task: replication with DSM-IV combined type, extension, and qualification, J Abnorm Child Psychol source

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    • cites [52] Wahlstedt, 2009, Neuropsychological deficits in relation to symptoms of ADHD: independent contributions and interactions, Child Neuropsychol source

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    • cites [53] Wahlstedt, 2009, Heterogeneity in ADHD: neuropsychological pathways, comorbidity and symptom domains, J Abnorm Child Psychol source

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A growing body of research addresses cognitive training in ADHD.

    “there is a burgeoning literature on cognitive training in ADHD [111, 112]”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [111] Epstein, 2010, Evidence for cognitive training as a treatment strategy for children with attention-deficit/hyperactivity disorder, J ADHD Relat Disord

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    • cites [112] Tamm, 2007, Can attention itself be trained? Attention training for children at risk for ADHD. Attention Deficit/Hyperactivity Disorder: Concepts, Controversies, New Directions, New York: Informa Healthcare

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  • May combine two claims.

    Interpretationreasoning

    Research on the effects of reward is mixed, possibly because the effects of incentives are not robust or because the magnitude, saliency, or targets of incentives varied considerably across studies.

    “Although it is well-documented that speeding the ERs attenuates ADHD-related RTV differences, research on the effects of the reward is quite mixed, possibly because the effects of incentives are not robust or because the magnitude, saliency, or targets of incentives applied has varied considerably across studies.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    One study suggests the effects of reward may be task-specific because reward improved performance only on tasks requiring inhibition.

    “Still another study suggests the effects of reward may be taskspecific because reward improved performance only on tasks require inhibition [41].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] Epstein, 2011, Effects of stimulant medication, incentives, and event rate on reaction time variability in children with ADHD, Neuropsychopharmacology source

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  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationnone given

    Event rates and rewards are both task manipulations that target the energetic and motivational states of individuals.

    “ERs and rewards are both task manipulations that target the energetic and motivational states of the individuals.”
    Quote in the paperSubstantial claim

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    Premisecitation

    In a study using ex-Gaussian indicators, older adults differed from young adults on both sigma and tau, suggesting that reaction time variability in older adults is due to both variable responding and extreme responding, as opposed to patients with ADHD for whom reaction time variability is composed primarily of extreme responses, tau.

    “For example, in a study using ex-Gaussian indicators, McAuley et al. [110] demonstrated that older adults differed from young adults on both ex-Gaussian variance indicators, sigma, and tau, suggesting that RTV in older adults is due to both variable responding (sigma) and extreme responding (tau), as opposed to patients with ADHD for whom RTV is composed primarily of extreme responses, tau.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [110] McAuley, 2006, Revisiting inhibitory control across the life span: insights from the ex-Gaussian distribution, Dev Neuropsychol source

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  • May combine two claims.

    Interpretationreasoning

    Medication effects on ex-Gaussian tau and fast Fourier transform indicators suggest that medication specifically reduces positive distributional skew, likely by decreasing the number, frequency, and/or magnitude of intermittent long reaction times.

    “Medication effects on ex-Gaussian tau and FFT indicators suggest that medication specifically reduces positive distributional skew likely by decreasing the number, frequency, and/or magnitude of intermittent long RTs.”
    Quote in the paperSubstantial claim

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    Premisecitation

    Other studies show that medication reduces tau and reduces the peak and skew of reaction time distributions.

    “These results suggest that medication specifically reduces intermittent long RTs, which is consistent with other studies showing that medication reduces tau [100] and reduces the peak and skew of RT distributions [43].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [100] Teicher, 2004, Novel strategy for the analysis of CPT data provides new insight into the effects of methylphenidate on attentional states in children with ADHD, J Child Adolesc Psychopharm source

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    • cites [43] Spencer, 2009, Stimulant treatment reduces lapses in attention among children with ADHD: the effects of methylphenidate on intra-individual response time distributions, J Abnorm Child Psychol source

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    Premisecitation

    ADHD-related increases in reaction time variability are attenuated, and may even normalize, with stimulant medication.

    “In general, ADHD-related increases in RTV are attenuated, and may even normalize, with stimulant medication [35,41,43,[97][98][99][100][101][102].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [35,41,43,[97][98][99][100][101][102]

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    Premisecitation

    Most studies using fast Fourier transform analyses have demonstrated that stimulant medication attenuated or normalized long reaction time oscillations in individuals with ADHD compared with controls, although one study failed to replicate this effect.

    “Also, most studies using fast Fourier transform (FFT) analyses have demonstrated that stimulant medication attenuated [35] or normalized [103] long RT oscillations in individuals with ADHD compared with controls, although 1 study failed to replicate this effect [104].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [35] Castellanos, 2005, Varieties of attention-deficit/hyperactivity disorder-related intra-individual variability, Biol Psychiatry source

      Not checked in the free run.

    • cites [103] Johnson, 2008, Dissociation in response to methylphenidate on response variability in a group of medication naive children with ADHD, Neuropsychologia source

      Not checked in the free run.

    • cites [104] Tucha, 2006, Effects of methylphenidate on multiple components of attention in children with attention deficit hyperactivity disorder, Psychopharmacol source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Although increased reaction time variability is present across populations, the characteristics of reaction time variability across populations are likely different.

    “It is likely that although increased RTV is present across populations, the characteristics of RTV across populations is likely different.”
    Quote in the paperSubstantial claim
37 of 37

  • The paper relies on this without support.

    Direct comparisons of reaction time variability between ADHD and other disorders with heightened reaction time variability are virtually nonexistent.

    “However, direct comparisons with other disorders with heightened reaction time variability are virtually nonexistent, despite their potential to inform our understanding of the phenomenon.”

  • The paper relies on this without support.

    The default mode network is a task-negative network that must be suppressed during task performance.

    “The DMN is considered a task negative network because it must be suppressed concomitant with activation in the task positive network (i.e., the neural network required to perform the cognitive task at hand).”

  • The paper relies on this without support.

    Long reaction times are the primary cause of reaction time variability in patients with ADHD.

    “which appears to be the primary cause of RTV for patients with ADHD.”

  • The paper relies on this without support.

    Neuroimaging research on reaction time variability in ADHD is much less common than in typically developing groups.

    “there are many fewer neuroimaging studies specifically investigating the phenomenon of RTV in ADHD.”
4 of 4

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Authors
Tamm, L., Narad, M. E., Antonini, T. N., O'Brien, K. M., Hawk, L. W., & Epstein, J. N.
Affiliations
  • Cincinnati Children's Hospital Medical Center (US)
  • University at Buffalo, State University of New York (US)
Corresponding author
Tamm, Leanne
ORCID
Venue
Neurotherapeutics
Publisher
Elsevier BV
Published
2012-07
Volume
9
Issue
3
Pages
500-508
ISSN
1878-7479 (ISSN-L)
DOI
10.1007/s13311-012-0138-5
PMC
PMC3441931
OpenAlex
W2021199892
Semantic Scholar
dcdc66de076d4895514570583dbbc7c0bbd00088
Cited by
324
References
114
Citations by year
2026: 22 · 2025: 12 · 2024: 18 · 2023: 28 · 2022: 29 · 2021: 35 · 2020: 25 · 2019: 27 · 2018: 25 · 2017: 20 · 2016: 27 · 2015: 20 · 2014: 24 · 2013: 11 · 2012: 1
FWCI
2.41
Type
journal article
Language
en
Open access
Licence
Locations
  • Neurotherapeutics (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Institute of Mental Health (K24MH064478)
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 variability, motivational incentives, attentional lapses, task-negative network, neurophysiological correlates, variability indices
MeSH terms
Attention Deficit Disorder with Hyperactivity, Humans, Inhibition, Psychological, Motivation, Neuropsychological Tests, Reaction Time

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-06.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-06.

Statistics and arithmetic are recomputed, not judged.

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