Figure 1.

A, Signal-in-noise and feature difference tasks for disparity, motion, and glass pattern orientation stimuli. Disparity tasks: for the signal-in-noise task, signal dots are either near or far relative to plane of fixation; for the feature difference task, the disparity of the surround is fixed and the disparity difference between the center and the surround is varied in fine steps. Motion tasks: for the signal-in-noise task, the dots in the surround are static, whereas the dots in the central target carry a net left or right motion direction; for the feature difference task, the direction of motion conveyed by moving dots in the surround is 30 degrees clockwise or counterclockwise from vertical, and the direction of motion conveyed by the dots in the center varies finely with respect to it. Glass pattern orientation: for the signal-in-noise task, dipoles in the surround carry random orientations, whereas dipoles in the center carry a net horizontal or vertical orientation; for the feature difference task, the orientation carried by the dot dipoles in the surround is 30 degrees clockwise or counterclockwise from vertical, and orientation carried by dipoles in the center varies finely with respect to it. B, The general protocol for the experiments testing on the different tasks (S-in-N, Signal-in-noise; FD, feature difference) before and after training. In Experiment 1, testing and training were restricted to the disparity tasks. In Experiment 2, testing covered all three visual cues and training took place over 2 d.