Each of the four Gabor patches was shown 72 times, the zebra was shown 36 times. The order of stimulus presentation was randomized. Each stimulus remained on screen for 39 refresh cycles (507 ms), with an additional variable inter-stimulus interval of either 24 (312 ms), 39 (507 ms), or 54 (702 ms) refresh cycles. A white fixation cross measuring 0.2° by 0.2° remained in the center of the screen for the duration of the task. Participants were asked to maintain fixation and to limit their blink frequency during the experiment.
