Schematic depiction of a trial from the verbal ISI 2s condition in which the test and the reference stimulus differed. Trials started with a bar that informed subjects about delay length (short bar: 2 s, long bar: 8 s) and type of stimulus pair (green bar: verbal, red bar: non-verbal). After this a fixation point appeared that remained in the centre of the screen for the rest of the trial. This was followed by the reference Gabor that was shown in either the upper right or lower left quadrant of the screen (here a trial with stimuli in the lower left quadrant are presented). The delay interval was presented afterwards (2 or 8 s), followed by the test Gabor that appeared in the same quadrant as the previous reference Gabor. During the following interval, the subject had to judge if the test and the reference stimulus had the same or a different orientation and press the corresponding button.