Fig. 1

Schematic illustration of a trial of the modified Sternberg task. The trial started with a white fixation cross at the middle of a black screen (first picture: “ + ”) that was presented for a randomly varying period of time between 10 and 12 s. The fixation cross was followed by an encoding period which lasted for 1.5 s. During this period participants had to encode a string of seven letters (second picture: “DUVLASY”). After, a retention period of 4.0 s (third picture: “ + ”) a single probe letter flanked by two questions marks on each side was shown for a maximum duration of 2.0 s (fourth picture: “?? U ??”). At this point, participants were instructed to decide as fast as possible (within the response window of 2 s) whether the probe letter had been included in the encoding period or not. Thereafter, the next trial started with an intertrial interval of 10–12 s (fifth picture: “ + ”)