 Some of the ways in which binocular summation improves binocular visual performance are

A practical measure of binocularity is the binocular summation ratio BSR, which is the ratio of binocular contrast sensitivity to the contrast sensitivity of the better eye.One might expect the inputs from each eye to simply add together, and that the perceived brightness with two eyes is twice that of a single eye.However, the perceived brightness with two eyes is only slightly higher compared to a single eye.