2.3.3. Near transfer tasks

Computerized digit-span forward (DSF) and backward (DSB) tasks were used as near transfer tasks. On each trial a fixation cross was presented for 750 ms, followed by a sequence of digits (0–9) displayed one at a time at a rate of 1000 ms in the center of the screen. At the end of the sequence, participants were asked to recall the digits in the same (DSF) or reverse (DSB) order that they appeared, typing their response into the answer box. There were two trials at each string length (DSF: 3–9; DSB: 2–8). If participants performed correctly on at least one trial of the two trials at a specific span length the string length was increased on the next trial. If participants performed incorrectly on both trials at a specific span length the task was terminated. The outcome measure was digit span, defined as the maximum string length at which participants repeated back the sequence in the correct order on 50% of trials.⁷ Further task details are reported in the Supplementary material.