Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 7 142 improvements in school performance. However, the evidence collected here suggests that behavioral improvements in particular may be predictive of better academic outcomes when treated with MPH. MPH Improves Feedback Learning but Not the Ability to Profit from Rewarded Feedback In contrast to our hypotheses, the evidence from Chapter 5 and 6 reveals that children with ADHD and TD profit equally from rewarded feedback. We found no evidence for impairments in the acquisition or reversal of stimulus-reward associations or the ability to profit from rewarded feedback. A possible explanation for these findings is the use of rewarded feedback, that is the combination of feedback (thumbs up, smiley, applause) in combination with a reward (monetary reward or points). Existing literature suggest that children with ADHD are more sensitive to this reward component than TD controls (Dovis, Van Der Oord, Wiers, & Prins, 2013; Luman et al., 2005). Therefore, it is possible that children with ADHD profited most from the addition of rewards in our experiments, resulting in comparable performance between the ADHD and TD groups. Further, it important to note that in daily life, learning may be more complex than the acquisition and reversal of stimulus-rewards associations in a standardized lab task. Especially during longer, more complex academic or cognitive tasks it is therefore likely that especially children with ADHD do experience problems with this type of learning in daily life in spite of these results. Concerning the effects of MPH, results from the studies described in Chapters 5 and 6 imply that MPH speeds up learning even when instrumental learning is intact. This is in line with previous studies (Luman et al., 2015) and also consistent with the view of MPH as a cognitive enhancer (Farah et al., 2004). Our findings of the potential role for MPH in improving generalization of knowledge are also in line with this latter view. However, the effect of MPH on generalization of knowledge was small and needs to be replicated in future studies. Our findings expand previous findings on deficits in generalization of knowledge from adults with ADHD to children with ADHD (Frank et al., 2007). Further, our results reveal that the positive effects of MPH on instrumental learning previously described are not due to placebo effects, which is important as placebo effects in RCTs are generally large (Krogsbøll et al., 2009). Further, MPH did not affect the ability to profit from rewarded feedback (Chapter 6). In combination with the limited effects of MPH on academic performance shown in the previous chapters, this suggests that the use of motivational strategies within classrooms should be increased. This suggestion is also in line with the finding that