Fig. 1.

A. Pre-training Task Procedure. A single centrally placed fixation cue (“+”) was presented, after which the cue circle (either blue or orange, rewarded or unrewarded) with the target appeared. B. Illustration of the trial procedure for the target discrimination task. Circles are shown in orange and blue to illustrate unrewarded and rewarded colors, respectively. Trials began with a fixation cross, followed by the cue and target screen. Participants were to report whether the target dot was in the top or bottom half of the circle by pressing one of two buttons as quickly as possible. C. Parametric manipulation of spatial probability. Participants were assigned to one of two target side high-probability groups, right or left. The staircase shown indicates the course of the task through blocks where the target becomes more likely to fall to one side. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)