FIGURE 1.

Experimental paradigm. Each trial started with an auditory cue, which carried information about the target’s location in half of the runs. After a variable interval of 2, 4, or 6 s, the target -a honeycomb pattern with one missing comb either at the top or at the bottom- appeared for 16.5 ms. After another 66 ms, a negative image of the complete pattern was presented for 16.5 ms, serving as the mask. Both target and mask appeared exclusively in the left visual field. Participants had to report in two binary-choice questions, first, which comb was missing and, second, whether they were sure or had guessed the answer.