Schematic of the task. A) First functional session: Subtraction and multiplication problems were presented in randomized order (120 trials). Participants had to choose the alternative that corresponds the solution. Response times were measured from the onset of the presentation of the alternatives. B) Second functional session: 60 multiplication problems were presented as Arabic numerals or as written number words in German language. Participants had to indicate if the solution is correct or not. Response times were measured from the onset of the presentation of the solution.