Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 4 84 was added every four trials and the position of stimuli were manipulated every two trials from positions with low to high memory load), which were presented in a 4x4 grid on a computer screen.. The task was terminated when the participant failed to accomplish both trials at a certain difficulty level. Reliability and validity of this task have been demonstrated (Nutley et al., 2009). The total number of correct responses multiplied by the highest difficulty level achieved served as the dependent measure. Reaction time (RT) speed, lapses of attention, and interference control were measured with a modified version of the Flanker task, which has adequate reliability and validity (Eriksen & Eriksen, 1974; Fan, McCandliss, Sommer, Raz, & Posner, 2002). Participants pressed one of two buttons corresponding to the direction of a target arrow presented on a computer screen. The target arrow was flanked by identical arrows (congruent), arrows pointing in opposite direction (incongruent) or horizontal rectangles (neutral). Following practice, four blocks of 12 trials were completed. RT speed was calculated from the neutral trials and corrected for accuracy to control for speed accuracy trade- off. For this purpose, inverse efficiency scores (mean RT divided by proportion correct) were used as dependent variables (Mullane et al., 2009b). Lapses of attention (tau) were reflected in the exponential component of the reaction time distribution, calculated using the model of Lacouture & Cousineau (2008) excluding trials with extreme slow responses (>3SD above the mean). Interference control was measured by calculating the difference between inverse efficiency scores in congruent and incongruent trials (Mullane et al., 2009b). Motivation and perceived academic competence Intrinsic motivation was measured using the Children’s Academic Intrinsic Motivation Inventory, which has adequate reliability (CAIMI; (Gottfried, 1986; Gottfried, 1985). This is a self-report questionnaire about the enjoyment of learning, comprising three subscales: General (18 statements), Math and Reading (each 26 statements). Items were scored on a 5-point Likert scale. Extrinsic motivation (sensitivity to punishment and reward) was measured using the parent-rated Sensitivity to Punishment and Sensitivity to Reward Questionnaire for Children (SPSRQ-C) (Colder & O’Connor, 2004; Luman, Van Meel, Oosterlaan, & Geurts, 2012). Punishment sensitivity (15 items; 5-point Likert scale) and Reward responsivity scales (7 items; 5-point Likert scale), were used. Self- perceived academic competence was measured using the School scale of the Self Perception Profile for Children, which as adequate reliability and content validity