Figure 1.

2-AFC Orientation-discrimination task. (A) The time course of a “both” trial in Experiment 1. Subjects fixated a spot at the center of the screen after which a Gabor patch appeared in the periphery (fixation cue: red dot; subject gaze: dashed yellow circle). After 100 ms the fixation dot jumped to the target, cueing the subject to initiate a saccade to the target. Once the saccade was detected, the contrast of the target changed (to equate foveal and peripheral sensitivity). The target remained visible for 200 ms after saccade detection. Subjects reported whether the target was oriented clockwise or counterclockwise relative to vertical. (B) Horizontal gaze trajectory on a single example trial. Screen center was at 0° and the target was at 5° (i.e., a saccade-right trial). Vertical lines indicate the saccade cue and the moment of saccade detection, at which point the contrast of the target changed. (C) Saccade end points for a typical subject. Each dot is the final position of the subject's gaze on a single trial. Shaded gray regions represent the Gaussian envelope of the target Gabor. Dashed circles mark the 2° error criterion. Trials that fell outside this region were not included in the analysis.