Fig. 1.

Experimental paradigm. (A) Visual condition: stimuli consisting of vertical, stationary gratings were presented in either the left or right lower visual field, while participants maintained central fixation. Stimuli were presented for 2 s followed by a 2-s baseline window. Analysis windows (1 s length) are indicated in blue for stimulation and in red for baseline. (B) N-back task: stimuli consisting of letters were presented for 200 ms at 2-s SOA. In the 0-back task (upper panel) the subject had to respond to the letter X. In the 2-back task the subject had to respond if the letter was the same as that of two stimuli back. (Targets are presented in green here for illustrative purposes only.) Analysis windows (1 s length) are indicated in blue on the time axis.