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Abstract:
Abstract: The stop signal task developed by Gordon Logan and
colleagues has been used increasingly as a measure of inhibitory
control in children. Recent versions of the task have used a
tracking algorithm that adjusts the stop signal delay during the
task to maintain an approximate stop failure rate of 50%. We have
used this version of the task on a touch screen system in a study
of children with and without early focal brain damage. The task has
7 blocks of 40 trials each, with no stop signals in the first block
and 25% stop trials thereafter. The initial stop signal delay is
based on the child's median reaction time in the first block and
adjusted thereafter by 50 ms increments to maintain 50% stop
failures. A preliminary analysis of 11 control children age 8-10
and 13 age 11-13 looked at age and sex effects and the
effectiveness of the tracking algorithm. Greater variability in the
stop signal delay early in the task and in go reaction time overall
was seen for younger children. Overall go reaction time, stop
signal reaction time, and percent stop failures did not differ.
However, a negative correlation between percent stop failures and
go reaction time suggests that tracking stopping time may be more
difficult in children with faster responding. Illustrations of stop
signal tracking during the task will be presented for individual
subjects.
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