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Abstract:
Recently, Barkley, Quay, and others have proposed that the
primary deficit in children with Attention Deficit Hyperactivity
Disorder (ADHD) is one of inhibitory control. Although much data
supports such a view, there are some inconsistencies in the
literature. Moreover, inhibition is a diverse construct with many
different components. It is not clear that children who have
problems with one type of inhibition (e.g., response inhibition)
will necessarily be impaired on other types of inhibition (e.g.,
filtering out distracting information). To explore fully the
validity and nature of the inhibitory control deficit in ADHD, we
tested children with and without ADHD on five different tests of
inhibitory control. The Color-Word Stroop test assessed negative
priming and inhibition of distracting information. A Simon/Erikson
task tested filtering ability and inhibition at the response
selection stage. A delayed eye movement task examined the ability
to suppress reflexive and memory-guided saccades. Inhibition of
return was measured in a covert visual orienting task using
uninformative peripheral cues. A stop-signal task measured the
ability to stop a visually-triggered response. We will report on
the degree to which children with ADHD differ from controls on the
measures of inhibition derived from these tasks, as well as on the
degree to which these inhibitory mechanisms covary. The findings
provide important evidence regarding theories implicating the
frontal-striatal loop in ADHD.
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