N-back taskThe two conditions of the N-back task were adopted from Colzato et al. (2013b). A stream of single visual letters (taken from B, C, D, G, P, T, F, N, and L) was presented (stimulus–onset asynchrony 2,000 ms; duration of presentation 1,000 ms). Participants responded to targets (presented in 33 % of the trials) and to nontargets.Half of the participants pressed the left shift key in response to a target and the right shift key in response to a nontarget; the other half of the participants received the opposite mapping. Target definition differed with respect to the experimental condition. In the 1-back condition, targets were defined as stimuli within the sequence that were identical to the immediately preceding one. In the 2-back condition, targets were defined as stimuli within the sequence that matched the one that was presented two trials before. Each block consisted of four cycles of the same task; each cycle comprised of 32 stimuli.