Anne Fleur Kortekaas-Rijlaarsdam

15 INTRODUCTION 1 been widely reported (Coghill, Seth, et al., 2014; Pietrzak, Mollica, Maruff, & Snyder, 2006). Because of these behavioral and cognitive improvements, positive effects of stimulants of academic performance are often assumed. Several reviews (Aman, 1980; Barkley, 1977; R. Barkley, Varley, & Nolan, 1978; Schachar & Tannock, 1993) and a meta-analysis (Prasad et al., 2013) have addressed this issue: Although the (older) reviews provide little evidence for positive effects of MPH on academic performance (Aman, 1980; Barkley, 1977; Barkley et al., 1978; Schachar & Tannock, 1993) a more recent meta-analysis (Prasad et al., 2013) demonstrated 9.7-14.4% improvements with medication compared to placebo in seatwork productivity (number of assignments completed) and on-task behavior (amount of time actively spend on seatwork). However, evidence for effects of stimulant medication on longer-term academic outcomes (e.g. grades, length and duration of education, the need for special education) is scarce and effect sizes are small which questions the clinical significance of these results (Arnold et al., 2015; Langberg & Becker, 2012). Although longer-term academic outcomes may be more ecologically valid than standardized achievement tests, for those long-term outcomes, the use of randomized controlled trials (RCTs) is unethical and therefore, evidence is likely to be confounded by placebo-effects and poor medication adherence. Therefore, much research on medication efficacy focusses on immediate effects of medication on academic performance. However, neither of these studies distinguished between different academic subjects (e.g. math, reading, spelling) while recent evidence indicates that medication efficacy differs between academic subjects, with larger effects for math than for reading (Murray et al., 2011). Moreover, although MPH improved seatwork productivity and on-task behavior, the pooled effect of MPH on the quality of academic performance (academic accuracy) was not significant and the number of studies reporting this was limited (Prasad et al., 2013). Thus, it remains unclear whether MPH improves core academic skills or just results in increased academic productivity without improving the quality of the work. The aim of this thesis is to investigate the effects of MPH on academic performance and learning. To this end, the first part of this thesis intends to quantify the effects of MPH on academic performance on productivity and accuracy while distinguishing between the core academic subjects (math, reading and spelling). Further, as feedback in academic contexts is considered crucial to improve knowledge, skill acquisition and academic motivation (Shute, 2008), an additional aim of this thesis is to quantify the effects of MPH on feedback learning an relate these findings to actual classroom performance.