Title: Interference Control and Resource Allocation in Adults with Attention-Deficit/Hyperactivity Disorder: An Evaluation of Response Variability and Error Compensation
Abstract: This research investigated intrasubject variability
in reaction time, interference control, and error compensation
during a flanker task in 37 adults with
Attention-Deficit/Hyperactivity Disorder (ADHD; 20 Combined
subtype, 17 Predominantly Inattentive subtype) and 26 healthy
controls. I hypothesized that, similar to children with ADHD,
adults with the disorder would demonstrate: (a) greater
interference control deficits than control subjects, as reflected
in greater effects of incongruent flankers on accuracy, reaction
time, and intrasubject variability; and (b) less post-error slowing
than controls, indicating difficulties with error compensation
associated with resource allocation deficits. Intrasubject
variability was assessed using the ex-Gaussian distributional model
and the deviation from the mode method. Across task conditions,
similar to pediatric samples, adults with ADHD demonstrated greater
intrasubject variability involving greater sigma, reflecting
relatively faster reaction times in the normal portion of the
curve, and greater tau, indicating greater variability in the
positive skew of the distribution. These results suggest that the
portion of the RT distribution affected in patients with ADHD is
consistent across the lifespan. Variability in child and adult ADHD
may be explained by the default-mode hypothesis, which emphasizes
the role of attentional lapses in performance. In contrast to
prediction, performance measures did not implicate a specific
deficit in interference control among adults with ADHD. In fact,
controls were more adversely affected by incongruent arrays with
respect to the proportion of correct responses, directional errors,
and nonresponses to targets. Only
for false alarms was there a
greater interference effect among adults with ADHD. However,
whereas previous studies have not found an elevated flanker effect
on intrasubject variability of patients with ADHD, the present
results indicated that adults with ADHD exhibited increased
variability with greater demands for interference control.
Intrasubject variability in adults with ADHD involved greater sigma
during flanker incongruent compared to congruent trials, reflecting
increased variability in the normal portion of the RT distribution.
In addition, adults with ADHD exhibited diminished post-error
slowing, a result consistent with previous findings for children
with the disorder. This deficit in executive functioning is present
in individuals with ADHD throughout development and can be
explained by the resource allocation hypothesis.
Publication Year: 2012
Publication Date: 2012-01-01
Language: en
Type: article
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