Examining the mechanisms of error monitoring: implications for attention deficit hyperactivity disorder

Error monitoring refers to a cognitive process whereby individuals monitor their performance or behaviour for the occurrence of errors. There are two proposed sub-processes in error monitoring: error detection and behavioural adjustment following errors. Error monitoring is crucial to behavioural regulation and learning, as the goal is to reduce the occurrence of errors, done through the effects of reinforcement learning. Previous research report that children with Attention Deficit Hyperactivity Disorder (ADHD) are deficient in error monitoring, however, the nature of the deficit remains unclear. Objective. The goals of the present thesis are to elucidate the nature of the deficit in error monitoring in children with ADHD by examining the two sub-processes of error detection and behavioural adjustment in separate experiments. Experiment 1 will examine error detection as participants indicate whether they made an error or a correct response on each trial of a modified flanker task. Experiment 2 measures behavioural adjustment, defined as the amount of slowing of reaction time following errors (termed post-error slowing). Experiments 3a and 3b explore the effect of motivational manipulations, including knowledge of results and reward/response cost, on post-error slowing. These manipulations were chosen as they are hypothesized to improve post-error slowing performance by influencing the processes involved in reinforcement learning. Results. Experiment 1 revealed that children with ADHD are able to detect their errors with similar accuracy as control children, suggesting no deficit in error detection. Experiment 2 found a significant difference between the two groups on post-error slowing. The ADHD group speed up their responses following errors, compared with the slowing displayed by the control group. Experiments 3a and 3b revealed no significant differences between the groups on post-error slowing in either the knowledge of results or the reward/response cost conditions. The means indicated that children with ADHD actually slowed more than the control group under the reward/response cost condition. Conclusions. Findings from this thesis indicate that children with ADHD are able to detect errors in their performance, however, demonstrate a deficit in their ability to engage in effective behavioural adjustment following errors. When knowledge of results is provided, children with ADHD improve their post-error slowing slightly; however, they demonstrate the most improvement under conditions of reward/response cost. The findings from this thesis contribute to the literature on error monitoring and ADHD in several ways. First, the results suggest that some individuals with ADHD have a deficit in error monitoring, consistent with the proposed difficulty with reinforcement learning posited by several theoretical models of the disorder. Second, results indicate that error monitoring can be influenced at a behavioural level by motivational factors and third, that the degree of motivation has an effect on error monitoring performance in ADHD. The improvement observed in the ADHD group under motivationally-mediated conditions has implications for structure within classroom settings and for behaviourally-based treatments of ADHD.

Keywords: Attention-deficit hyperactivity disorder
Attention-deficit hyperactivity disorder, Treatment
Attention-deficit-disordered children
Attention-deficit-disordered children, Education
Cognition in children