Evidence for Higher Reaction Time Variability for Children With ADHD on a Range of Cognitive Tasks Including Reward and Event Rate Manipulations

Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
Neuropsychology (Impact Factor: 3.27). 04/2011; 25(4):427-41. DOI: 10.1037/a0022155
Source: PubMed


The purpose of the research study was to examine the manifestation of variability in reaction times (RT) in children with attention deficit hyperactivity disorder (ADHD) and to examine whether RT variability presented differently across a variety of neuropsychological tasks, was present across the two most common ADHD subtypes, and whether it was affected by reward and event rate (ER) manipulations.
Children with ADHD-combined type (n = 51), ADHD-predominantly inattentive type (n = 53), and 47 controls completed five neuropsychological tasks (Choice Discrimination Task, Child Attentional Network Task, Go/No-Go task, Stop Signal Task, and N-back task), each allowing trial-by-trial assessment of RTs. Multiple indicators of RT variability including RT standard deviation, coefficient of variation and ex-Gaussian tau were used.
Children with ADHD demonstrated greater RT variability than controls across all five tasks as measured by the ex-Gaussian indicator tau. There were minimal differences in RT variability across the ADHD subtypes. Children with ADHD also had poorer task accuracy than controls across all tasks except the Choice Discrimination task. Although ER and reward manipulations did affect children's RT variability and task accuracy, these manipulations largely did not differentially affect children with ADHD compared to controls. RT variability and task accuracy were highly correlated across tasks. Removing variance attributable to RT variability from task accuracy did not appreciably affect between-groups differences in task accuracy.
High RT variability is a ubiquitous and robust phenomenon in children with ADHD.

Download full-text


Available from: Joshua M Langberg
  • Source
    • "By contrast, one of the rare studies that did not report a significant difference between interference effects when comparing ADHD patients and control subjects also failed to report differences in RTs (Banich et al., 2009). Slower RTs have been found to be characteristic of ADHD responding in several different tasks (e.g., Alderson et al., 2007; Castellanos et al., 2005; Epstein et al., 2011; Johnson et al., 2007; Leth-Steensen et al., 2000; Lijffijt et al., 2005; Oosterlaan et al., 1998). Chronometric analyses indicated that motor times (MT) were not different between groups, refuting the idea that patients with ADHD are slowed at the motor execution level. "
    [Show abstract] [Hide abstract]
    ABSTRACT: A deficit in "interference control" is commonly found in adults with Attention Deficit Hyperactivity Disorder (ADHD). This has mainly been interpreted as difficulties in inhibiting inappropriate responses. However, interference control involves processes other than simply the ability to inhibit. Consequently, we used sophisticated analysis to decipher the additional processes of interference control in these patients. We compared interference control between 16 adults with ADHD and 15 control adults performing a Simon task. In most studies, performance is generally reported in terms of mean error rates and reaction times (RTs). However, here we used distribution analyses of behavioral data, complemented by analyses of electromyographic (EMG) activity. This allowed us to better quantify the control of interference, specifically the part that remains hidden when pure correct trials are not distinguished from partial errors. Partial errors correspond to sub-threshold EMG bursts induced by incorrect responses that immediately precede a correct response. Moreover, besides "online" control, we also investigated cognitive control effects manifesting across consecutive trials. The main findings were that adults with ADHD were slower and showed a larger interference effect in comparison to controls. However, the data revealed that the larger interference effect was due neither to higher impulse expression, nor to a deficit in inhibition but that these patients presented a larger interference effect than the controls after congruent trials. We propose and discuss the hypothesis that the interference control deficit found in adults with ADHD is secondary to impairments in sustained attention. Copyright © 2015. Published by Elsevier B.V.
    Full-text · Article · Jun 2015 · Acta psychologica
  • Source
    • "High values of tau indicate instances of long RTs in the RT stream. These long RTs characterize one of the primary sources of increased RT variability in children with ADHD (Epstein et al., 2011; Tamm et al., 2012). In the current study, we focused on the T-scores for omissions, commissions , and hit reaction time, as well as tau. "
    [Show abstract] [Hide abstract]
    ABSTRACT: To explore the relationship between the Conners' Kiddie Continuous Performance Test (K-CPT) performance and parent-report measures of child behavior and executive functioning, and clarify the role of sex in K-CPT performance in preschoolers. Mothers and children recruited to the Health Outcomes and Measures of the Environment Study with complete 5-year assessment data relevant to the analyses were included (N = 127). We examined the association between K-CPT scores and Behavior Assessment System for Children-Second Edition (BASC-2) and Behavior Rating Inventory of Executive Function (BRIEF) scores, with covariate adjustment. We found no significant associations between K-CPT, BASC-2, and BRIEF scores in the full sample. In sex-stratified analyses, we found unusually fast reaction time on K-CPT was related to executive control difficulties in girls, whereas unusually slow reaction time was related to the same difficulties in boys. Omission errors were associated with executive difficulties only in boys. The K-CPT may prove to be a useful indicator for early onset of executive control difficulties in preschool-aged children. © 2015 SAGE Publications.
    Full-text · Article · Apr 2015 · Journal of Attention Disorders
  • Source
    • "In addition, our findings suggest that task characteristics may also influence effect size estimates, with smaller effects of diagnosis on tasks with minimal cognitive demands (simple GNG tau ES = 0.32) compared to tasks with greater cognitive demands (complex GNG tau ES = 0.46). Finally, reaction times were limited to a maximum of 2300 ms (the trial duration), which may have reduced estimates of tau compared to longer response windows used in previous studies (e.g.,5 s in Epstein et al. 2011). However, a study with a similar response window (e,g., 2250 ms trial duration in Hervey et al. 2006) but a greater percentage of boys in their sample (77 %) and a different task (Conners' CPT) demonstrated larger diagnostic group differences (ES = 0.82) than in our study. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Children with attention-deficit hyperactivity disorder (ADHD) consistently show impaired response control, including deficits in response inhibition and increased intrasubject variability (ISV) compared to typically-developing (TD) children. However, significantly less research has examined factors that may influence response control in individuals with ADHD, such as task or participant characteristics. The current study extends the literature by examining the impact of increasing cognitive demands on response control in a large sample of 81children with ADHD (40 girls) and 100 TD children (47 girls), ages 8-12 years. Participants completed a simple Go/No-Go (GNG) task with minimal cognitive demands, and a complex GNG task with increased cognitive load. Results showed that increasing cognitive load differentially impacted response control (commission error rate and tau, an ex-Gaussian measure of ISV) for girls, but not boys, with ADHD compared to same-sex TD children. Specifically, a sexually dimorphic pattern emerged such that boys with ADHD demonstrated higher commission error rate and tau on both the simple and complex GNG tasks as compared to TD boys, whereas girls with ADHD did not differ from TD girls on the simple GNG task, but showed higher commission error rate and tau on the complex GNG task. These findings suggest that task complexity influences response control in children with ADHD in a sexually dimorphic manner. The findings have substantive implications for the pathophysiology of ADHD in boys versus girls with ADHD.
    Full-text · Article · Jan 2015 · Journal of Abnormal Child Psychology
Show more