Figure 1.

Sample stimuli presented to the left and right eyes (LE and RE). (A) A pair of discs with luminance increment from a dark background (Experiment 1a). (B) A pair of discs with luminance increment from a light background (Experiment 1a). (C) A pair of discs with luminance decrement from a light background (Experiment 1b). Test discs luminance differed in the two eyes, but the standard discs luminance was identical. (D) A pair of discs with luminance increment from a dark background with a concentric black circle only in the LE (Experiment 2a). (E) A pair of discs with luminance increment from a dark background with a black circle in each eye, one near the top of the LE disc and the other near the bottom of the RE disc (Experiment 2b). The target luminance was inside the top circle. (F) Stimuli for Experiment 2c. (G) Second-order contrast modulated (CM) gratings for Experiment 3 to measure the perceived CM phase and depth when interocular CM depth ratio (equal carrier contrast in the two eyes) or interocular carrier contrast ratio (equal CM depth in the two eyes) varied.