Schematic diagrams of stimulus configurations and task procedure.

<p>(<b>a</b>) Illustration of dichoptic stimulus presentation; (<b>b</b>) Illustration of two stimulus configurations. In the positive configuration, the phase of the grating in the weak eye was shifted by <i>θ/2</i> ( = 45°) from the midline while the phase in the strong eye was shifted by <i>-θ/2</i>. In the negative configuration, the phase-shift was reversed; (<b>c</b>) An example of the perceived phase (<i>θ</i>′) versus interocular contrast ratio <i>δ</i>. The perceived phase was measured as a function of interocular contrast ratio. The resulting data were fitted with the attenuation model <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100156#pone.0100156-Huang1" target="_blank">[7]</a> 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.