Schematic diagrams of stimulus configurations and task procedure.

(a) Illustration of dichoptic stimulus presentation; (b) Illustration of two stimulus configurations. In the positive configuration, the phase of the grating in the weak eye was shifted by θ/2 ( = 45°) from the midline while the phase in the strong eye was shifted by -θ/2. In the negative configuration, the phase-shift was reversed; (c) An example of the perceived phase (θ′) versus interocular contrast ratio δ. The perceived phase was measured as a function of interocular contrast ratio. The resulting data were fitted with the attenuation model [7] to compute effective contrast ratio. The black solid line is the best fit of the model. The dotted arrow line (magenta) indicates the estimated effective contrast ratio for this normally-sighted subject.