An examination of the effects of stimulant medication on actual and self-perceived response inhibition: a comparison between children with and without attention deficit hyperactivity disorder

• Main Author: Brackenridge, Rachel Ann
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2007
• Subjects: Experimental psychology

This study aimed to investigate whether methylphenidate medication was effective in improving response inhibition in children with ADHS, using a newly developed measure of response inhibition – the Animal Stroop Task. A between subjects design was used to compare a group of children with ADHD and a control group of normally developing children on measures of response inhibition, locus of control and behavioural attributions. Participants with ADHD were tested in two separate conditions – unmedicated and medicated. Additional within the subjects comparisons were used to compare response inhibition and behavioural attributions across the two conditions. There was no significant difference between the inhibitory control of children with ADHD and those of children in the control group, but children with ADHD did show a significant improvement in inhibitory control following methylphenidate medication. There was no difference between the Locus of Control scores of children with and without ADHD and no significant relationship between locus of control and inhibitory control in any condition. Children with and without ADHD did not differ in the degree to which they attributed their performance to external factors and these attributions did not vary as a function of medication status. The current findings contradict previous evidence documenting deficits in the inhibitory control of children with ADHD, and challenge the well-established theory that poor response inhibition is the cardinal feature of ADHD. Reports of Methylphenidate improving the functioning of children with ADHD are supported but there is no evidence to suggest that children with ADHD are any more likely to make external attributions for their behaviour, irrespective of medication status.