Figure 2.

Illustration of the discrimination tasks. Participants fixated on a central nonius fixation. (A) In the depth task, the disparity of dots in the central plane varied finely across trials and was either “near” or “far” relative to the surrounding annulus. Participants judged the disparity difference between regions. (B) In the luminance task, the luminance of the central dots varied relative to the surrounding dots. Participants judged whether the central dots were darker or lighter than the surround dots.