Use of private speech during math computation in children with attention deficit hyperactivity disorder, methodological challenges, task performance and effects of stimulant medication

'Objective'. To delineate and utilize a rigorous methodological approach to investigate private speech and the effects of stimulant medication in children with Attention Deficit Hyperactivity Disorder (ADHD). Multiple distinct objectives were included: (1) to explore a rigorous methodological approach to the study of private speech in children; (2) to examine task performance and its relationship to private speech; (3) to examine the effects of stimulant medication on private speech in children with ADHD and (4) to investigate private speech in children with ADHD and their normal peers. 'Method'. Three approaches were used in this thesis. The first approach was to systematically review the literature for methodological differences in the study of private speech using a 'rating scale' approach. Secondly, task performance, error patterns and overt behavior of children with ADHD, on and off medication, explored the relationship between private speech and task performance. The third approach was to conduct an empirical investigation to test the hypothesis that children with ADHD are deficient in their production of private speech and/or inefficient in their use of private speech to regulate behavior. This was accomplished by conducting both a comparative study between children with ADHD and their typically developing peers and a randomized double blind placebo controlled medication trial for children with ADHD. 'Results'. First, it was found that methodological differences in the study of private speech in children are innumerable. Second, children with ADHD demonstrated lower levels of academic efficiency, used more immature computational strategies and exhibited increased levels of inattention and disruptive behavior during a math computation task. The comparative study demonstrated that ADHD and non-ADHD children differed in the sub-types of private speech emitted but not in overall amounts of private speech produced. Children with ADHD produced more overt on-task private speech and less internalized private speech compared to their non-affected peers. Furthermore, the medication trial showed that the effects of stimulant medication were positive, resulting in increased developmental maturity of private speech. ADHD children were produced more internalized private speech and less overt private speech. 'Conclusions'. Results across the three approaches suggest that the study of private speech in atypical populations, particularly ADHD is a promising avenue of research. Two of these studies support the notion that a systematic approach to the study of private speech is warranted. When children with ADHD are given tasks that are individually mapped to ability level they are not deficient in their production of private speech, but rather exhibit a functional deficit. It would be beneficial for future research to address the potential misuse of global matching of tasks at age or grade level to elicit private speech in children. Lastly, this thesis speaks to the two prevailing theories (Vygotsky & Barkley) on the relationship between private speech and behavior. Should the results of the empirical study of private speech contained in this thesis be replicated in future research it suggests that children with ADHD may have a higher order difficulty that affects a number of behavioral responses, including but not necessarily limited to private speech.