Figure 1. Experimental paradigm and behavioral results.

(A) In the sensory processing blocks, the noise/grating stimuli were irrelevant and unattended. In the perceptual decision making blocks, a decision had to be made regarding the presence or absence of a grating. Grating visibility is enhanced for illustrative purposes. (B) Example stimuli. The noise level in perceptual decision making blocks was tailored to individual detection thresholds. (C) Average response proportions in perceptual decision making blocks, for grating present and grating absent trials, color-coded according to the four stimulus/response-categories. The numbers denote the average number of trials available in each of these categories. Error bars depict standard deviations.