This study investigated the movement preparation (reaction time) and movement execution (movement time) of children with and without ADHD by manipulating the uncertainty of occurrence. Participants performed a seated lower extremity choice response time protocol, which contained either 10% catch trials or 30% catch trials along with 27 empirical stimuli to one of three target directions. Results indicated that children with ADHD were significantly slower at processing lower extremity movements than their peers for the condition with increased number of catch trials, but not the condition with fewer catch trials. These findings suggest that children with ADHD are more affected by the uncertainty of an empirical stimulus during the preparation phase of a movement response than their age-matched peers are.
Scott J. Pedersen and Paul R. Surburg
Scott J. Pedersen, Paul R. Surburg, Matthew Heath and David M. Koceja
The purpose was to investigate central and peripheral processing mechanisms through the use of electromyography (EMG) to determine differences between the performance of children with and without ADHD on a lower extremity choice response time task. Sixteen children with ADHD were tested on and off medication along with 19 children without ADHD. For premotor time, the comparison group performed significantly faster than children with ADHD. The longer latencies exhibited in central processing of children with ADHD were related to midline crossing inhibition (MCI). Medication improved the speed of processing for children with ADHD, but did not negate MCI.