Understanding and improving elementary learning abilities in children with ADHD: an experimental back-to-basics approach

Reinforcement learning is often assumed to be deficient in children with ADHD, yet elementary learning processes are rarely the subject of research in this population. This doctoral dissertation examined two elementary forms of learning in children with ADHD; 1) the ability to learn to select the most adaptive behavioural option in light of contextual information (conditional discrimination learning) and 2) acquisition and extinction under partial reinforcement learning in ADHD and the Partial Reinforcement Extinction Effect [PREE], an important concept for the understanding of behavioral persistence in the absence of reinforcement. In addition, their relation to known deficits in ADHD such as altered reward sensitivity or motivational processing and impaired short-term or working memory are studied. Results showed that children with ADHD, relative to comparable children without ADHD, exhibit neither a partial reinforcement acquisition deficit nor a deficit in PREE. Results showed that children with ADHD on averaged performed less well than comparable children without ADHD, particularly when a delay was imposed between the presence of contextual information and the choice behaviour. This difference was not mediated by individual differences in short-term memory, working memory or delay aversion. Moreover, conditional discrimination learning performance under delay was a better predictor for clinical caseness (ADHD diagnosis) than measures of short-term memory, working memory or delay aversion. Furthermore, deficits in conditional discrimination learning can be reduced by increasing the value of reward for correct responding or through a Differential Outcomes procedure (in which correct choice behaviour is rewarded with a sample-specific reinforcer rather than a generic one). Of relevance for the long-term effectiveness of behavior therapy, gradual stretching of reinforcement facilitated response acquisition relative to purely partial reinforcement while fully preserving behavioral persistence under extinction. Knowledge of elementary learning processes and their remediation has important implications for the optimization of interventions like behavioral parent training, whose cornerstone is the shaping of adaptive behavior through elementary learning processes.status: publishe