Clinical suppression and binocular rivalry suppression: the effects of stimulus strength on the depth of suppression

In observers with abnormal binocular vision (such as strabismics or anisometropes) one eye's view is often suppressed. This clinical suppression serves to eliminate binocular diplopia and confusion. Suppression may also occur in observers with normal binocular vision, when the two eyes view disparate retinal images, a phenomenon known as binocular rivalry. When the image in an eye is suppressed, it is possible to determine the amount by which that suppressed stimulus is below the visibility threshold, or the depth of suppression. In the experiments presented here, the depth of suppression in an eye was measured as the strength of the stimulus in the contralateral eye (the stimulus inducing suppression) was varied. This was done for both clinical suppressors and normal observers undergoing binocular rivalry suppression. Independent changes were made to the contrast, the luminance, and the spatial frequency of the inducing stimulus. For both clinical suppression and binocular rivalry suppression, the depth of suppression was constant, regardless of the changes to the inducing stimulus.