Interocular non-independence

Binocular interaction was studied by presenting a different letter form to each eye via a dichopic tachistoscope. The two dissimilar letters were presented simultaneously or at short delay internals of 0–200 msec and were either presented on corresponding or non-corresponding retinal areas. At delay internals of less than 100 msec stimulation of corresponding areas resulted in identification performance below that to be expected on the basis of independent chances to perceive. Stimulation on non-corresponding areas resulted in both presented letters being identified at the accuracy level predicted by an independence assumption.