Figure 1.

Discrimination tasks used for testing and training in the present study. (A) Direction discrimination. Subjects were first instructed to fixate on a central target. Eye tracking enforced fixation during stimulus presentation, aborting trials during which fixation moved > 1 degree of visual angle from the fixation target. After an initial 1000-ms fixation period period, a moving stimulus appeared peripherally for 500 ms. The subjects pressed the right arrow key if they perceived rightward motion, and the left arrow key if they perceived leftward motion. Direction discrimination was performed with either drifting gratings or moving dots. (B) Orientation discrimination was measured under the same constraints. Subjects pressed the left arrow key if they perceived a vertical stimulus orientation and the right arrow key if they perceived a horizontal stimulus orientation. Orientation discrimination was measured with either drifting gratings or static Gabors. Actual stimuli used in different conditions are shown in Figures 2–7.