Figure 1. General experimental design and behavioral performance in the working memory task.
(A) Experimental design. A subsequently masked target square was flashed in 1 out of 20 positions. Subjects were asked to report this location after a delay of up to 4 s and to rate the visibility of the target on a 4-point scale. A visible distractor square with features otherwise identical to the target was shown on 50% of the trials during the retention period (at 1.75 s). In a perception-only control condition, the maintenance phase and location response were omitted, and subjects assessed the visibility of the target immediately after the mask. (B) Spatial distributions of forced-choice localization performance in the working memory task (experiment 1; 0 = correct target location; positive = clockwise offset). Error bars indicate standard error of the mean (SEM) across subjects. The horizontal, dotted line illustrates chance-level at 5%. Percentages show proportion of target-present trials from a given visibility category. Due to low number of trials in individual visibility ratings 2, 3, and 4, all seen categories were collapsed for analyses.