Procedural arithmetic learning task
The arithmetic learning task consisted of a procedural learning and a fact learning part. The latter is analyzed in depth in an ongoing work on arithmetic learning and only mentioned for completeness. For procedural training, participants were presented with a problem in the form A # B. The problems were to be solved by 2 * B–A + 3, hence 4 # 37 = 71, as 2 * 37 = 74 74–6 = 68 68 + 3 = 71. Over the course of the 5 training days, participants were presented with a total of 300 trials. These consisted of 168 (56 on day 1 and 28 on days 2–5) procedural training problems and 4 fact learning problems (appearing once on day 1 and 8 times each on days 2–5). Each procedural trial started with a fixation cross appearing on the screen for 1 s, after which the problem was presented for 8 s and participants were instructed to press a button whenever they have finished calculating. Following that, three options were presented on the screen and participants were instructed to select their solution by pressing one of the three respective buttons within 3 s. One of the presented options was the correct option and the other two options called distractors were randomly generated. Feedback was presented after each trial to tell the participants if they chose the right option or not.