The manuscript addresses attention skill, as assessed with the ACT in children with dyslexia. For a full description of the reading and spelling remediation program, and all measures see the manuscript of Experiment 1 (Walda, Van Weerdenburg, Van der Ven, & Bosman, 2022). Data of Experiment 1 were previously deposited in DANS-EASY (https://doi.org/10.17026/dans-258-kq8c). An important finding of Experiment 1 is that many children with dyslexia (about 65%) were unable to finish 25 consecutive bars of the ACT at pre-test. Even at later moments of measurement within the nine months of the remediation program, when they had gotten more used to the task, many children failed to complete the ACT without making any error. Thus, regardless of whether they were exposed to the ACT training, children with dyslexia failed to complete the ACT and also hardly mastered the task of the ACT at a later moment. The present (second) experiment is designed to further investigate this unexpected finding. To enhance the possibility of increasing attention skills, we used an adaptive procedure of the ACT training for children with dyslexia who were unable to complete 25 bars of the ACT without making any errors. In the present experiment, two questions were addressed: 1. Does an adaptive procedure of the ACT training affect ACT performance in children with dyslexia during a remediation program? 2. Does the adaptive procedure of the ACT training affect progress in literacy in children with dyslexia during a remediation program? The experimental design was a randomized controlled trial, using two moments of measurement administered in a one-to-one assessment setting. The pretest (T1) took place prior to the adaptive ACT training, and a follow-up measurement was administered after the adaptive ACT training and three months of reading and spelling remediation (T2). In the README.pdf file, the process of collecting data is described, followed by an overview and description of variables included in the data set.

Comparing the datasets of Experiment 1 and Experiment 2, three main differences appear: 1. The dataset of Experiment 1 contains data of more participants. Participants in the dataset of Experiment 2 are a sub selection of participants in the dataset of Experiment 1. 2. The participants in the experimental group of Experiment 2 were subjected to a more intensive and adaptive ACT training than the participants in the experimental group of Experiment 1. 3. The dataset of Experiment 2 contains data on two measurement moments (pre and post ACT training), whereas the dataset of Experiment 1 contains data on four moments of measurement.