EEG data was processed using EEGLAB (Delorme and Makeig, 2004) and the ERPLAB plugin (http://erpinfo.org/erplab), running on MATLAB. Trials with blink artifacts were corrected by independent component analysis (ICA). Epochs were created time-locked to the onset of the relevant stimulus (cue, target or feedback), including a 200 ms pre-stimulus period, that was used for baseline correction. The total time window of the epoched ERPs varied according to the kind of stimulus, with the post-stimulus length equal to the duration of the stimulus presentation plus the time window of the shortest ISI. Epochs with horizontal eye movements detected by a step function (with threshold 60μV and moving window of 400 ms in the bipolar EOG channel) were rejected. We also rejected trials with drifts larger than −/+ 200 μV in any scalp electrodes. For cue-related data, this led to the rejection of 6% of epochs on average for the different cueing conditions, for which rejection rates were very similar (ranging from 5.6% to 7.2%). For the targets, on average 4.5% of the epochs were excluded, with minimal differences between conditions (range
