Aims: 

Colour discrimination from photoreceptors data is trivariate. Disparity discrimination (stereopsis) from binocular neurons is also a trivariate system. We propose to check if both discrimination systems are similar in order to quantify discrimination. For it, we will use a model based on discrimination ellipses.

Methods: 

Measurements of disparity discrimination data were taken from a stereoscopic device. 23 patients took part in the experiments. Disparity discrimination was measured for different positions within the Panum area and along different directions. Experimental data were adjusted to a discrimination ellipse. Data on disparity discrimination were compared with classical results on color discrimination.

Results: 

Disparity discrimination data were significantly fit to ellipses for all patients. Orientation and ellipse axes differ for the different zones of binocular space. Discrimination data are more irregular for points far from the fixation point. Discrimination-disparity ellipses show similarities to ellipses obtained for color discrimination from sensitivity curves of photoreceptors (cones L, S and M).

Conclusions: 

Experimental data show that physiological mechanisms to quantify colour discrimination and disparity information are similar and they are based in an equivalent trivariate system. Disparity neurons and photoreceptors data are managed in a further stage with a similar procedure although in different parts of the visual path.