Fig 1. Stimuli.

Band-pass filtered noise patches (1–6 cpd, 10° orientation bandwidth). Top row, a target presented to one eye. Middle rows, orthogonal competitors presented to the other eye. Bottom row, split competitor, parts of which were presented to each eye. Fixation point and black circular fusion frame were presented to both eyes throughout the experiment to stabilize the fixation and vergence so that the images presented to the two eyes would be aligned. In the main experiment, the right eye was the target eye and the left eye was the competitor eye. Two observers participated in additional experimental sessions in which the left eye was the target eye and the right eye was the competitor eye (See Psychophysics in Methods and Materials).